Elements of wooden truss roofs. How to make a gable roof truss system with your own hands

The frame format stands out among a number of types of roofing. It can be done in quite different ways, but in any case, you will need to calculate the rafters and install them according to all the rules. With proper knowledge of the problem, you can solve it on your own without resorting to specialists.

Features and forms of the roof

The frame roof can only be installed with spans no longer than 1220 cm, while the gap from one truss to another is a maximum of 0.6 m. The dimensions of the frame fragments are determined by the span distances and the calculated snow load. Rafters can be either freely installed or accepting loads from attic elements. In the case of a broken roof, it is possible to provide a ceiling height sufficient for a residential attic, and it will look best on a square structure.

The multi-gable roof is considered the most complex and hardly accessible variation for amateur builders. A balanced truss system effectively withstands even very high loads, while having an excellent "appearance". Since the slope is steep, the risk of snow retention will be minimal. But at the same time, all structural elements will have to be calculated very carefully, and a lot of waste will appear in the process. In addition, the valley will have to survive exposure to a significant amount of snow.

Purpose and types of systems

In the most different systems rafters can be used Mauerlat. The mass of the roof of the house varies depending on the area occupied by the slopes and the materials used. But in any case, the load created is very solid. When there is a ridge on the structures, a truss frame must be provided, with legs resting against the walls. Force is applied along several vectors at once, and in the cold season, the accumulation of snow only exacerbates the problem.

Mauerlat is designed to eliminate this shortcoming and prevent the destruction of the walls. This word means a beam of significant section, which can be both wooden and steel. In most cases, they take the same material that was used to form the rafters, but be sure to achieve the continuity of the strapping or create strong and especially stable joints. The use of Mauerlat is abandoned only in log houses or in buildings built according to frame technology- yes, and there are parts that perform a similar task. When it is not possible to make a non-breaking block, all fragments must be exactly the same length.

For T-shaped roof characteristic insertion of two wings at a certain angle. Because of this, it is necessary to form a valley. The outer rafters will rest against the support boards. In addition to them, there will also be basic parts that are directly fixed to the wall. In order for everything in the valley to correspond to the task being solved, wooden elements 3.8 cm thick are used. The crate is supposed to be made monolithic, the coating is attached to it with clamps every 50 cm. steel, you can slightly reduce this figure.

A reinforcing belt is often equipped under the Mauerlat. This is especially important if you plan to insulate the roof and provide reliable waterproofing. Such a belt is formed from the same mixture that is used to build the foundation. Completely the entire formwork is poured with concrete in one step, the slightest individual layers are unacceptable. In the aerated concrete wall, intermediate jumpers are cut down at the top line of blocks - and a practical gutter immediately appears. The Mauerlat is attached either with a tie wire, or with reinforcing bolts (but they will not help in any way without a reinforcing belt), or with building studs.

Having dealt with the support for the rafters, you need to find out what they can be, and what is more correct to use to support the roof. Hanging rafters are used if there is no main wall inside the building, their support points are located exclusively on the outer contours.

Such supports were in demand during the construction of:

• residential buildings with one span;
• production facilities;
• various pavilions;
• attic.

This option should not be underestimated, thanks to engineering developments, suspended rafters are able not to bend, covering spans of 15–17 m. But it is important to understand that they gain all their capabilities only in close interaction with other details. You will have to use puffs, and grandmas, and crossbars. The simplest truss is made of two beams connected in the upper position; in configuration, such a device is close to a triangle. The horizontal connection of the frame parts is provided by a tightening (a beam made of wood or a metal profile).

Due to the tightening, the transfer of thrust to the walls is excluded, while the force applied in the horizontal plane is suppressed. The outer walls experience the action of only those forces whose vector is oriented vertically. Builders do not always place a puff at the very bottom, often it is set at the very ridge. In preparation for the construction of the attic, this element is most often placed higher than the base of the rafter legs. Then it will be possible to make a floor, on the ceiling of which you will not have to beat your head with any careless movement.

Hanging rafters for spans longer than 6 m must be reinforced with hangers and braces. In this case, the monolithic puff is replaced by one assembled from a pair of connected beams. In the classical scheme (triangular hinged), the grassroots bases abut against horizontal parts. For the normal functioning of the system, it is required that the height of the ridge is at least 15% of the span of the trusses. The rafters act on the bend, but tightening does not allow them to move to the sides. In order for the beams to bend less, the ridge knots are cut in with the expectation of eccentricity (the occurrence of a bending force opposite in vector).

Mansard attics are built for the most part with the help of triangular arches on three hinges, and the puffs are assigned the function of floor beams. The components of the tightening are bolted by means of an oblique or direct cut. Raised tightening can also be used in the construction of rafters under the attic. The higher it rises, the more the ceiling can be raised. But it is important to remember that at the same time, the loads on all elements also increase. The transfer of forces is carried out on the Mauerlat with the help of a movable mount, which dampens dimensional changes due to changes in humidity and temperature.

The rafters can be subjected to uneven loading, since it is higher on one side. This leads to a shift in the same direction of the entire system. You can eliminate such an unpleasant effect if you take out the rafters beyond the contour of the walls. The tightening with such a decision ceases to be a support, it transfers either tensile effects (if an attic is being arranged), or stretched-bending ones (when an attic is being built). Hinged arches with the inclusion of a crossbar differ from the previous version by replacing the sliding support with an identical one in function - rigid. Due to the change in the type of supports, the type of stresses generated also becomes different, the rafter system turns into a spacer.

The puff is formed in the upper lobe of the arch. Its purpose is to endure no longer a stretch, but a compressive effect. Additional tightening, reinforcing the crossbar, is needed with a significant load. Arches with suspensions and struts complement the arch systems with headstocks. Such a system is needed for significant spans (from 6 to 14 m). The struts that correct the resulting bend must rest against the headstock. Regardless of the particular type truss system it is necessary to carry out as accurately as possible all the details and their bundles with each other.

Not always hinged rafters can perform the task. Then the slanting elements come to the rescue. This type of rafters is used under hip roofs and under roofs equipped with a valley. Their length is longer than in the usual case. In addition, they become supports for the shortened rafters of the slopes. That is why the load on the rafters is about 50% more than in other designs.

Thanks to the increased length, it is possible to:

• resist significant impacts;
• form beams without cuts;
• bring the parts to a single size by pairing the boards.

To build a hip roof with many spans, the diagonal legs are provided with supports. Such supports are made in the form of standard struts or racks of timber, or a pair of connected boards. Support through a lining made of wood and a waterproofing layer is made directly on the reinforced concrete floor. The struts are placed at an angle of not less than 45 and not more than 53 degrees, at the bottom such a detail rests on the beds. The angle of installation is less important than the ability to fix parts of the rafters at the point experiencing the strongest load.

Sloping rafters placed in openings up to 750 cm should be held by struts only in the upper lobe. With a length of 750 to 900 cm, a truss truss or rack is additionally mounted below. And if the total span length exceeds 9 m, then for maximum reliability in the middle you need to put a rack, no other support will do. If the selected floor is unable to withstand the load, it will have to be reinforced with a beam. The type of support in the ridge is determined by how many intermediate supports are used, what they are, how the key layered rafters are made.

In addition to the type of rafters, you need to clearly understand their material. Both wooden and metal structures can be good, but only each in its place. Even the high strength of the metal does not allow to push the usual wood. The tree has proven its benefits for thousands of years, and now it is even gaining popularity due to its excellent ecological characteristics. Boards and timber can be bought at affordable price, and if something was not taken into account, it is always easy to saw off the desired fragment or build up the part right on the construction site.

Sometimes there are problems associated with the operation of the created structures. Wooden rafters will have to be carefully treated with antiseptics, as well as means that block the development of mold colonies and insects. The combustibility of wood is suppressed due to regular processing, and in addition, it is too difficult to find the necessary components for slopes longer than 7 m. Before installation, the walls are laid with a mauerlat, made from a log frame or based on a block of timber. The thickness of the structures is at least 180 mm, this is the only condition for a uniform distribution of loads.

Metal rafters are inevitably heavier than wood rafters for the same section. Therefore, the walls need to be strengthened, the work on their construction becomes more expensive and longer. It will not be possible to mount metal blocks manually; cranes will be required. It is impossible or very difficult to adjust the dimensions, the geometry of the rafters, so you will immediately have to build the walls as accurately as possible and eliminate errors during their construction. The slightest mistake can make an expensive block almost useless in practice.

Metal rafters are connected by welding, and welded joints are inevitably weakened, as corrosion develops rapidly there. The cost of the work is very high, and when performing them, it is necessary to comply with the requirements of fire and electrical safety. But there is such an indisputable advantage as the ability to support a roof slope from 700 cm and longer. If you use a special anti-corrosion paint, the durability of metal structures is fully guaranteed. All these advantages allow you to quickly and comfortably build industrial building with considerable height and length of spans.

How to choose: what to consider?

The truss system should be chosen as correctly and clearly as possible.

When looking for a suitable solution, you need to pay attention to the following points:

• strength;
• the ability to support the slopes and the roof as a whole of a certain size and geometry;
• creating a positive aesthetic image of the building as a whole.

Technical specifications are of priority. Even the most beautiful structures that follow the principles of design will not show their positive qualities if they last too little. Experienced builders always analyze the average annual and seasonal temperatures, the financial capabilities of developers, the maximum possible wind speed and the severity of the overlying roof. The future use of the under-roof space and the scale required for it are also taken into account. Wind, snow and rain should not be underestimated, since these factors can have a very strong effect on the roof, and through it on the rafters.

If it is reliably known that a particular area is characterized by heavy snowfalls, the minimum slope angle is impractical. This point is even more relevant when using flat roofs. Under the pressure of accumulating precipitation, the frame can rapidly deform or water will pour inside. Another thing is when a certain region is often subject to the arrival of cyclones and the strong winds they bring. Here the slope should already be made smaller, then the situation with the disruption of individual structural elements will be practically excluded.

Mistakes can be avoided if you look at houses already built nearby and operated for a long time. By accurately reproducing their roof structure and the rafter system interconnected with it, one can best take into account local specifics. But not everyone follows this path, sometimes the task is to develop exclusively original project. Then you will have to carefully collect the initial data, carry out scrupulous calculations. In the absence of special knowledge, it is better to attract qualified performers to help.

After analyzing the total load created by wind and snow, it can sometimes be found that certain parts of the truss complex need selective reinforcement. When assessing the required angle of inclination of the roof, attention is also paid to the type of coating used. A heavy metal tile or corrugated board with a very large slope can spontaneously slide down, you have to additionally fix them, complicating your work and increasing the cost of installation. In addition, certain materials have a tendency to retain water or become soaked with it, which can only be combated by making the slope steeper. Creating a good roof and truss system that meets such conflicting requirements is not always accessible to non-specialists.

What does it consist of?

The structure of the truss system, as you can see, is quite complex and even contradictory. Each part of this design has a strictly defined role. So, Mauerlat is a long bars of coniferous wood, and strictly resinous wood is used for work. Such elements are laid out along the external load-bearing walls, attached to the base with anchors or rods of a special design (threaded). This part transfers the load from the roof to the wall.

Next comes such a device as a rafter leg. Under this name appears a wooden beam used to build the contour of the slopes. The shape of the structure is always triangular, because it is the best way to help the roof withstand the destructive effects of winds, snow and other atmospheric processes. Rafter legs are placed at uniform distances along the entire roof, the step cannot exceed 120 cm.

The bed is also of some importance for supporting the roof - this is a wooden block that replaces the Mauerlat in some cases. Beds are placed on the internal supporting walls. They turn into the basis of the roofing triangle. Thanks to them, the slopes do not crawl under their own weight. And it is also worth mentioning about the racks - these are bars with a square section placed vertically. They perceive the pressure exerted downward by the ridge assembly and transmit it mechanically to the inner bearing plane. Sometimes the racks are under the rafters.

Struts are designed to strengthen the entire structure of the roof, they connect the legs and beds into one whole. This detail is shaped like a rhombus. The community formed by the puff and struts is called the farm. In addition to them, you also need a crate, which is thin boards stuffed at right angles to the legs of the rafters. It helps to keep the rafter legs as a single system. Absolutely any roof covering is attached to the crate.

Under soft materials, the crate should be made inseparable, and best remedy considered plywood. At the very top is a ridge, which logically and physically completes the roofing triangle. The connection of a pair of opposing legs of the rafters is provided by a square piece of wood which prevents the entire roof from collapsing. And at the very bottom of the pitched roof there is an overhang, which extends approximately 0.5 m from the perimeter. Thanks to him, the streams of rain leaving the roof do not flood the outer bearing planes and do not harm them.

Fillies are used only in the situation when the rafter legs cannot be made along the length that would allow organizing the overhang. Connecting with boards of reduced section effectively solves this problem. For fastening the wooden elements of the rafters, it is most often recommended to use clamps, staples. It is undesirable to use nails, because the tree pierced by them becomes weak and fragile after a few years. Therefore, if professionals use connections made directly on the construction site, they use bolts.

But even a bolted connection weakens building structures, albeit relatively slightly. The strongest are the connections with the help of clamps or staples made of metal. Only their industrial production can maximize the quality of products, since deviations from the norms and deterioration in quality are excluded only under strictly standardized and fully controlled conditions. You can assemble a truss structure from completely finished trusses very quickly, there is no risk in using it. Another thing is that it is required to collect information about the necessary characteristics as accurately as possible and transfer it to the manufacturer without distortion.

In addition to these elements, the truss system borders on the valley. This is the name given to a special connection of a geometrically complex roof at points where its trajectory changes. The difference from the ridge is that in such places the roofing parts form a negative angle. The technical essence of the product lies in the fact that the gutter helps to divert liquid to the side. The more complex the configuration, the greater the number of such gutters should be.

The cornice beam serves to abut a strut against it, the other end of which rests against the frontal board, while the dropper is not deformed and its configuration is not distorted. Wind connections are those elements of the truss system that transfer the load created by the wind from the roof to the foundation. They not only increase the overall stability of the structure, but also help to avoid tipping over in case of instability of individual parts. The roof will retain spatial rigidity even with very strong winds.

Horizontal wind connections are such elements as:

• braces;
• parabolic puffs;
• complexes of conventional puffs;
• trusses, complemented by a cross-shaped lattice.

Vertically, the preservation of characteristics under strong air pressure is ensured by wind supports and beams. Sometimes a monolithic reinforcing core is used. Engineers have come up with many other options for designing a wind connection. It is provided with frames and semi-frames, pinched props. In small buildings, rigid (resisting compression) or stretched diagonals are used, some covering two spans at once. The location of each of the elements is accurately reflected in the project documentation.

It is not so difficult to understand the qualitative characteristics of truss systems and their composition, if you show care and diligence. But it is equally important to calculate the quantitative parameters of these systems. If you do not do this or make the calculations incorrectly, you can either spend too much money, or encounter leaks, even with the destruction of individual elements.

• roof bends;
• average annual snow mass;
• unevenness in its distribution along the slopes, depending on the steepness of the slope and the wind rose;
• wind transfer of already fallen snow;

• descent of snow and ice masses, runoff of liquid water down;
• aerodynamic characteristics and windage of the structure;
• differences in the strength of the impact on individual points.

It is not so easy to calculate everything necessary, moreover, by simulating realistic situations and including a reasonable margin of safety in the project. Moreover, it is necessary to pay attention to the addition of various loads, to their cumulative effect. But still, any customer is quite capable of evaluating the quality of the work of designers. The loads applied to the truss systems are divided into three key groups: main, additional and extreme.

The main category includes:

• stable factors - the severity of the roof and roof structures, additional elements installed on top of them;
• long-term effects - snow, temperature;
• periodically changing factors - full calculations of snow and temperature effects, taking into account all the subtleties.

An additional group is the pressure exerted by the wind, builders and repairmen, ice and rain. The extreme category includes all natural and man-made emergencies that may occur in a particular place. Their level is predicted with a margin to ensure the exclusion of unpleasant consequences. When calculating frame roof and the structures under it, the ultimate load is taken into account, in the case of which the entire structure crumbles. Additionally, an indicator or a group of indicators is given, upon reaching which various deformations inevitably appear.

The snow drift coefficient reflects how much more snow will be deposited on the lee side and in front of objects (parts) that block the air flow. In problem areas, you will have to bring the rafters as close as possible and thoroughly calculate the required thickness of the front material. The most accurate assessment of all parameters can only be given by multiplying any received figures by the reliability factors. As for the wind, the force developed by it is aimed at dropping steep roofs and lifting from the leeward section of a flat roof. We must not forget that the air flow acts simultaneously on the facades and on the roof slopes.

When hitting the facade, the air breaks up into two waves: one goes down and is no longer of interest, and the other tangentially presses on the roof overhang, trying to raise it. The action on the slope occurs at a right angle, this area is pressed inward. At the same time, a vortex is formed, which tangentially affects the windward sector of the ramp. This vortex bypasses the ridge and begins to create lift already applied to the leeward segment. For your information: when calculating the mass of the roof, you need to take into account the severity of the rafters, insulation, waterproofing and vapor barrier.

Standard load per 1 square meter roof is up to 50 kg, regardless of its size and other significant circumstances. By changing the distance from one rafter leg to another, you can set the actual distribution of loads on them. According to most experts, indicators from 60 to 120 cm will be acceptable values. But on an insulated roof, it is worth choosing such distances that are equal to one sheet or roll of insulation materials. At the same time, it should be taken into account that among several suitable options the arrangement of rafters is preferable to the one that gives the best effect with the minimum consumption of materials used.

When calculating the loads carried by the rafters, they always look at the fact that they do not exceed the maximum endurance roofing material. After all, there is no point in such an excess. If, under the planned impact, the roof will still begin to sag, it is impossible to talk about a solid result. When calculating, the payload from structures connected to truss trusses is calculated according to the touch area that is plotted on the drawing. Such structures include ventilation chambers, attic and ground floor ceilings, and water tanks placed on the roofs. In addition to the amount of pressure on the rafter system, the sharpness of the roof slope is also calculated.

Tilt angle: value

On forums with consultations of specialists and in professional literature, one can find references to three units of measurement of inclination at once. In addition to the usual and expected degrees, there will be percentages and ratios between the parties. Often they get along together even within the same publication or instruction from the manufacturer of roofing materials. But in fact, there is nothing mysterious in this, any consumer can understand the essence. Under the angle of inclination of the roof, experts understand the angle that occurs at the intersection of the horizontal with the roof slope.

Obtuse corners in this case, it can't be. Moreover, you can meet a slope steeper than 50 degrees only in decorative elements, all kinds of turrets. An exception to general rule become only slopes on the lower rows of rafters mansard roof. In all other cases, the angles range from 0 to 45 degrees. The relative proportions of the sides are calculated as the ratio between the height of the slope and its projection on the horizontal. This indicator is equal to half the span for a uniformly constructed roof with a pair of slopes.

On a shed roof, the proportion is equal to one, but in more complex configurations, you still have to carry out all the calculations and estimates yourself, without starting from ready-made values. The slope angle is usually expressed as a fraction, with the numerator and denominator separated by a colon. But when the resulting numbers cannot be rounded to whole numbers, it is recommended to use percentages: they simply divide one by the other and increase it a hundred times. Flat roofs are those that have a slope of no more than 5 degrees; a slope of 6–30 degrees is recognized as small, and all other roofs are considered to be steep. flat design radically increases the usable area and is quite resistant to wind, but it will be necessary to clean it of snow manually and strengthen the waterproofing to the limit. The slope is necessarily consistent with the specific material, and required values can be found in the manufacturer's instructions. In order to calculate even the most complex and bizarre roof configurations, they are mentally divided into triangles and the angle is calculated separately in each.

Step, length and section of rafters

When it became clear how long the slopes are, what angles formed by these slopes with a horizontal plane, it was time to do the actual calculation of the rafters. If the roof frame is made of a 5x15 cm timber under a metal tile, the mounting pitch sways from 0.6 to 0.8 m. As the slope grows, the gap also increases. If the roof slopes at 45 degrees, you need to put rafters every 800 mm, and for slopes of 75 degrees, you can add another 200 mm.

The next important parameter is the length of the rafters. It is closely related to the step: if the blocks are made long, they are brought together as much as possible, and when a single part is shortened, they are moved apart. When calculating the step of the crate, they proceed from the type of tiles laid on top and from the fact that an integer number of rows should be laid out on each slope. If you get a fraction, it is better to round, reduce or increase the indicator a little. The rafter legs under the metal tile, the cross section of which is 15x5 cm, range from 65 to 95 cm. You cannot increase the step when the cross section of the crate is 3x5 cm.

In order for the insulation to be better ventilated, rows of holes with a diameter of 1–1.2 cm are prepared in the region of the upper edge of the rafters. Ordinary rafters under the corrugated board go every 0.6–0.9 m. with significant cross section. The crate under the corrugated board is assembled from boards with dimensions of 3x10 cm, which are placed at intervals of 0.5 m. The interval must be calculated according to the height and thickness of the materials.

With all the revealed shortcomings of slate, it remains widely in demand. Under the slate roof, rafters with a section of 5x10–15 cm are mounted, 60–80 cm apart from each other. Most often, an average distance of 0.7 m is recommended. Pauses between parts of the crate are calculated according to the steepness of the material. On relatively flat areas, the support of 4 pieces of wood justifies itself. If the roof is made steeper, put 3 bars, separated by 63–65 cm.

We must not forget that due to the responsibility of the truss system, it is better to leave a margin of safety than to make an unreasonably weak type of rafters. For their manufacture, timber is used, dried to a maximum of 15%. A non-edged board of the same dryness can serve as a replacement for a beam. Under the ceramic tiles, a 5x5 cm timber crate is used. In the places marked according to the calculated distance, slate nails or simple self-tapping screws are used.

Installation: technology

The construction of the roof involves the use of a standard range of carpentry tools and an electric drill. If metal structures are used, a grinder will be required for precise cutting. Remember that it is impossible to process metal tiles or corrugated board with it, this can damage the material. A hipped roof without racks is made using puffs that reinforce the structure.

AT hip variant you have to strengthen the runs running diagonally. Paired boards and a particularly strong timber are assigned to them. Connection points always have a support (stand), and the main support is placed about a quarter of the length separating the large rafters from the ridge. Under the gables on a gable roof, rafters of a shorter length are always made. But under the main part of the four-slope structure, extremely long parts can be placed, even more than 7 m. To keep them securely, either a rack is used that transfers stress to the ceiling or a sprengel.

The first step in creating rafters under a broken roof is the formation of a support complex in the form of the letter P. It rests on the floor beams and is held by rafter legs. Next, they put three or more runs, two of them are brought to the corners of the frame, and the rest are placed in the middle of the overlap. The final step in raftering is fixing the legs. It is desirable to make truss systems according to a pattern - to connect two boards that are the same length as the rafters, and pin them to each other with a nail. The template is placed with its edges at the points of attachment of the rafter legs and fixed with a cross member.

An additional template (this time plywood) will help to make a mounting saw. Farms are attached to the Mauerlat, starting from the extreme ones. In order not to confuse with the attachment point of the ridge, the tops of these trusses are tied with a straight rope. The massiveness of the puffs increases as you approach the ridge. If the truss elements are bolted, washers or plates should be used. This will keep the nuts from digging into the wood.

How to install the rafters with your own hands, see the video below.

Rafters perform a number of significant roofing functions. They set the configuration of the future roof, perceive atmospheric loads, and hold the material. Among the rafter duties, the formation of even planes for laying the coating and providing space for the components roofing cake.

In order for such a valuable part of the roof to flawlessly cope with the listed tasks, information about the rules and principles of its construction is needed. The information is useful both for those who are building a gable roof truss system with their own hands, and for those who decide to resort to the services of a hired team of builders.

In device roof frame for pitched roofs using wooden and metal beams. The starting material for the first option is a board, log, timber.

The second is constructed from rolled metal: channel, profile pipe, I-beam, corner. There are combined structures with steel most loaded parts and wood elements in less critical areas.

In addition to the "iron" strength, the metal has a lot of disadvantages. These include heat engineering qualities that do not satisfy the owners of residential buildings. Disappointing need for the use of welded joints. Most often, industrial buildings are equipped with steel rafters, less often private change houses assembled from metal modules.

In the case of self-construction of truss structures for private houses, wood is a priority. It is easy to work with it, it is lighter, “warmer”, more attractive in terms of environmental criteria. In addition, nodal connections do not require a welding machine and welder skills.

Rafters - a fundamental element

The main "player" of the frame for the construction of the roof is the rafter, among the roofers called the rafter leg. Beds, braces, headstocks, girders, puffs, even Mauerlat may or may not be used depending on the architectural complexity and dimensions of the roof.

The rafters used in the construction of the gable roof frame are divided into:

• Layered rafter legs, both heels of which have reliable structural supports under them. The lower edge of the layered rafter rests on the Mauerlat or on the ceiling crown of the log house. The support for the upper edge can be a mirror analogue of an adjacent rafter or a run, which is a beam horizontally laid under the ridge. In the first case, the truss system is called spacer, in the second, non-spacer.
• hanging rafters, the top of which rests against each other, and the bottom is based on an additional beam - puff. The latter connects the two lower heels of adjacent rafter legs, resulting in a triangular module called a truss truss. The tightening dampens the tensile processes, so that only a vertically directed load acts on the walls. The design with hanging rafters, although it is spacer, does not transfer the spacer itself to the walls.

In accordance with the technological specifics of the rafter legs, the structures constructed from them are divided into layered and hanging. For structural stability, they are equipped with struts and additional racks.

For the arrangement of supports for the top of the layered rafters, beds and girders are mounted. In reality, the truss structure is much more complicated than the elementary patterns described.

Note that the formation of a gable roof frame can generally be carried out without roof structure. In such situations, the alleged planes of the slopes are formed by slegs - beams laid directly on the bearing gables.

However, we are now specifically interested in the device of the gable roof truss system, and it can involve either hanging or layered rafters, or a combination of both types.

Subtleties of fastening rafter legs

The rafter system is fastened to brick, foam concrete, aerated concrete walls through the mauerlat, which in turn is fixed with anchors.

Between the Mauerlat, which is a wooden frame, and the walls of these materials in without fail a waterproofing layer is laid from roofing material, hydroisol, etc.

The top of the brick walls is sometimes specially laid out so that something like a low parapet is obtained along the outer perimeter. So it is necessary that the Mauerlat placed inside the parapet and the walls do not burst the rafter legs.

The rafters of the roof frame of wooden houses rest on the upper crown or on ceiling beams. The connection in all cases is made by cutting and duplicated with nails, bolts, metal or wooden plates.

How to do without furious calculations?

It is highly desirable that the cross section and linear dimensions of the wooden beams be determined by the project. The designer will give clear calculation justifications for the geometric parameters of the board or beam, taking into account the entire range of loads and weather conditions. If there is no home design development master at his disposal, his path lies on the construction site of a house with a similar roof structure.

You can ignore the number of storeys of the building under construction. It is easier and more correct to find out the required dimensions from the foreman than to find them out from the owners of a shaky unauthorized construction. After all, the foreman is in the hands of documentation with a clear calculation of the loads per 1 m² of roof in a particular region.

The installation step of the rafters determines the type and weight of the roofing. The heavier it is, the smaller the distance between the rafter legs should be. For laying clay tiles, for example, the optimal distance between the rafters will be 0.6-0.7 m, and for a profiled sheet, 1.5-2.0 m is acceptable.

However, even if the step required for the correct installation of the roof is exceeded, there is a way out. This is a reinforcing counter-lattice device. True, it will increase both the weight of the roof and the construction budget. Therefore, it is better to deal with the step of the rafters before the construction of the rafter system.

Craftsmen calculate the pitch of the rafters according to the design features of the building, tritely dividing the length of the ramp into equal distances. For insulated roofs, the step between the rafters is selected based on the width of the thermal insulation boards.

On our website you can find, which may also help you a lot during construction.

Rafter structures of layered type

Rafter structures of the layered type are much simpler in execution than their hanging counterparts. A justified plus of the layered scheme is to provide full ventilation, which is directly related to the longevity of the service.

Distinctive design features:

• Mandatory presence of support under the ridge heel of the rafter leg. The role of the support can be played by a run - a wooden beam resting on racks or on the inner wall of the building, or the upper end of an adjacent rafter.
• The use of Mauerlat for the construction of a truss structure on walls made of brick or artificial stone.
• The use of additional runs and racks where the rafter legs, due to the large size of the roof, require additional support points.

The minus of the scheme is the presence structural elements affecting the layout of the internal space of the operated attic.

If the attic is cold and the organization of useful premises is not supposed to be in it, then the layered construction of the truss system for the installation of a gable roof should be preferred.

A typical sequence of work on the construction of a layered truss structure:

• First of all, we measure the height of the building, the diagonals and the horizontalness of the upper cut of the skeleton. When detecting vertical deviations of brick and concrete walls, remove them cement-sand screed. Exceeding the heights of the log house we squeeze. By placing chips under the Mauerlat, vertical flaws can be dealt with if their magnitude is insignificant.
• The floor surface for laying the bed must also be leveled. He, the Mauerlat and the run must be clearly horizontal, but the location of the listed elements in the same plane is not necessary.
• We process all wooden parts of the structure before installation with fire retardants and antiseptic preparations.
• on concrete and brick walls we lay waterproofing for the installation of a Mauerlat.
• We lay the Mauerlat beam on the walls, measure its diagonals. If necessary, we slightly move the bars and turn the corners, trying to achieve the perfect geometry. Align the frame horizontally if necessary.
• We mount the Mauerlat frame. The splicing of the beams into a single frame is carried out by means of oblique cuts, the joints are duplicated with bolts.
• We fix the position of the Mauerlat. Fasteners are made either with brackets to wooden plugs laid in the wall ahead of time, or with anchor bolts.
• We mark the position of the bed. Its axis should recede from the Mauerlat bars at equal distances on each side. If the run will be based only on racks without lying down, the marking procedure is carried out only for these columns.
• We install the bed on a two-layer waterproofing. We fasten it to the base with anchor bolts, connect it to the inner wall with wire twists or staples.
• We mark the installation points of the rafter legs.
• We cut out racks according to uniform sizes, because our bed is set to the horizon. The height of the racks must take into account the dimensions of the section of the run and the bed.
• Installing racks. If provided by the project, we fix them with spacers.
• We lay the run on the racks. We check the geometry again, then install the brackets, metal plates, wooden mounting plates.
• We install a trial rafter board, mark the places of trimming on it. If the Mauerlat is set strictly to the horizon, there is no need to adjust the roof rafters in fact. The first board can be used as a template for making the rest.
• We mark the installation points of the rafters. Folk craftsmen for marking usually prepare a pair of slats, the length of which is equal to the gap between the rafters.
• According to the markup, we install the rafter legs and fasten them first at the bottom to the Mauerlat, then at the top to the run to each other. Every second rafter is screwed to the Mauerlat with a wire bundle. In wooden houses, the rafters are screwed to the second crown from the top row.

If the rafter system is done flawlessly, the layered boards are mounted in random order.

If there is no confidence in the ideal structure, then the extreme pairs of rafters are installed first. A control twine or fishing line is stretched between them, according to which the position of the newly installed rafters is adjusted.

The installation of the truss structure is completed by installing the filly, if the length of the rafter legs does not allow the formation of an overhang of the required length. By the way, for wooden buildings, the overhang should “go beyond” the contour of the building by 50 cm. If the organization of the visor is planned, separate mini-rafters are installed under it.

Another useful video about the construction of a gable truss base with your own hands:

Hanging truss systems

The hanging type of truss systems is a triangle. The two upper sides of the triangle are folded by a pair of rafters, and the puff connecting the lower heels serves as the base.

The use of tightening allows you to neutralize the effect of the thrust, therefore, only the weight of the crate, the roof, plus, depending on the season, the weight of precipitation, acts on walls with hanging truss structures.

The specifics of hanging truss systems

Characteristic features of hanging type truss structures:

• Mandatory presence of a puff, made most often of wood, less often of metal.
• The ability to refuse the use of Mauerlat. A frame made of timber will be successfully replaced by a board laid on a two-layer waterproofing.
• Installation on the walls of ready-made closed triangles - roof trusses.

The advantages of the hanging scheme include the space under the roof free from racks, which allows you to organize an attic without pillars and partitions. There are disadvantages.

The first of these is the limitation on the steepness of the slopes: their slope angle can be at least 1/6 of the span of a triangular truss, steeper roofs are strongly recommended. The second disadvantage is the need for thorough calculations for the competent device of cornice nodes.

Among other things, the angle of the truss truss will have to be set with jewelry accuracy, because. the axes of the connected components of the hanging truss system must intersect at a point, the projection of which must fall on the central axis of the Mauerlat or the lining board replacing it.

Subtleties of long-span hanging systems

Puff - the longest element of the hanging rafter structure. Over time, it, as is typical of all lumber, deforms and sags under the influence of its own weight.

Owners of houses with spans of 3-5m are not too concerned about this circumstance, but owners of buildings with spans of 6 meters or more should think about installing additional parts that exclude geometric changes in tightening.

To prevent sagging in the installation scheme of the truss system for a large-span gable roof, there is a very significant component. This is a pendant called a grandmother.

Most often, it is a bar attached with wooden surfs to the top of the truss truss. You should not confuse the headstock with the racks, because. its lower part should not come into contact with the puff at all. And the installation of racks as supports in hanging systems is not used.

The bottom line is that the headstock, as it were, hangs on a ridge knot, and a tightening is already attached to it with the help of bolts or nailed wooden plates. Threaded or collet type clamps are used to correct slack.

Adjustment of the tightening position can be arranged in the zone of the ridge knot, and the headstock can be rigidly connected to it with a notch. Instead of a bar in non-residential attics, reinforcement can be used to manufacture the described tightening element. It is also recommended to arrange a headstock or suspension where the puff is assembled from two bars to support the connection area.

In an improved hanging system of this type, the headstock is complemented by strut beams. The stress forces in the resulting rhombus are extinguished spontaneously due to the competent arrangement of the vector loads acting on the system.

As a result, the truss system pleases with stability with a slight and not too expensive upgrade.

Hanging type for attics

In order to increase the usable space, the tightening of the rafter triangles for the attic is moved closer to the ridge. A perfectly reasonable move has additional advantages: it allows you to use puffs as the basis for filing the ceiling.

It is attached to the rafters by cutting with a semi-frying pan with a duplication of a bolt. It is protected from sagging by installing a short headstock.

A noticeable drawback of the attic hanging structure is the need for accurate calculations. It is too difficult to calculate it on your own, it is better to use a ready-made project.

Which design is more cost effective?

Cost is an important argument for an independent builder. Naturally, the price of construction for both types of truss systems cannot be the same, because:

• In the construction of a layered structure for the manufacture of rafter legs, a board or beam of small section is used. Because layered rafters have two reliable supports under them, the requirements for their power are lower than in the hanging version.
• In the construction of a hanging structure, the rafters are made of thick timber. For the manufacture of puffs, a material similar in cross section is required. Even taking into account the rejection of the Mauerlat, the consumption will be significantly higher.

Saving on the grade of material will not work. For the bearing elements of both systems: rafters, purlins, beds, Mauerlat, attendants, racks, lumber of the 2nd grade is needed.

For crossbars and puffs working in tension, you will need the 1st grade. In the manufacture of less responsible wooden slips, the 3rd grade can be used. Without counting, we can say that in the construction of hanging systems, expensive material is used to a greater extent.

Hanging trusses are assembled in an open area next to the object, then transported assembled upstairs. To lift weighty triangular arches from a bar, you will need equipment, for which you will have to pay rent. And the project for complex nodes of the hanging version is also worth something.

Video instruction on the installation of a truss structure of a hanging category:

There are actually many more methods for constructing truss systems for roofs with two slopes.

We have described only the basic varieties that are actually applicable for small country houses and buildings without architectural designs. However, the information provided is sufficient to cope with the construction of a simple truss structure.

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It is hard to imagine a house without a roof. Without it, the house cannot be called complete. The roof is known to protect the house from precipitation, inclement weather, etc. In addition, with the help of it, the architectural image of the constructed object is completed. In this case, it is necessary to correctly calculate and install roofing system, only then the roof will last long years, and it does not need to be repaired every year.

The device of rafters can be very different. We propose to consider their most common types and types, methods of their attachment.

As you know, the roof can be flat or pitched. As for suburban construction, in this case, the installation of a gable roof truss system is especially popular. If the house is very large, then the roof will in this case be of the appropriate size, for example, four-pitched (more: ""). Thus, the developer must imagine the device of the truss roof system. by the most simple option the device of the truss system is considered pitched roof because it is very time consuming and requires sufficient knowledge.

Nevertheless, it is worth noting that the installation of a gable roof truss system is today considered the most common option. The design consists of two planes that are on the same level. They are also the supporting part that rests on the walls of the house. Usually there is an attic under the roof slopes. If it is heated, then it can be used as attic floor where you can equip a functional room.

It is worth noting that the angle of inclination of the future roof will depend on the roofing material. It is usually measured in degrees.

Determination of the reliability of the truss system

When constructing a roof, developers pay special attention to the truss system. It must be made reliable, because the service life of the roof structure depends only on this system.

The following points usually affect the reliability of the truss system:

Rafter roof device: structural units

It can be concluded that with an incorrect and unprofessional calculation of the truss system, it may simply not withstand the load in the future. In this case, terrible consequences cannot be avoided.

When calculating the design of the truss system, the following points should be taken into account:

• roof shape;
• location of internal supports;
• the span of the floors;
• expected operating loads.

In the design of the truss system, the triangle is the main figure. Rafter legs are also important in such a design, their device must be given maximum attention. Usually they are laid along the slope of the roof. The crate is supported just with the help of rafter legs.

What are the rafters

Today rafters can be:

• hanging;
• layered.

The optimal sections themselves will be the following options:

• for boards - 16-18x4-5 cm;
• for bars - 16-18x12-14 cm;
• for round timber - 12-16 cm.

The axis distances between the bars and logs should be 150-200 centimeters. The distance of the rafters between the bars of the boards is usually 100-150 centimeters.

At the end of each rafter leg, so-called fillies should be nailed. For their implementation, a regular board is suitable. A formwork must be nailed along the entire eaves along the slope of the filly, which will serve as the basis for the boardwalk. It is on this flooring that the roof material is attached.

The device of the truss system of a gable roof or any other may face such difficulty as thrust (read: ""). To avoid spreading the rafter system, the rafters must be attached to the ridge very tightly.

With the wrong device, slope displacement may also occur. If the rafter legs are cut into the floor of the tree, then this will not happen. The strength of the joint can also be achieved with an overlay, or with reliable fasteners, which are made using bolts, dowels.

In this case, it is necessary to take especially seriously the calculation of the maximum load of the roof, and we must not forget about the snow cap. Price roofing works in this case, it will increase significantly, since more lumber will be required, and the tile itself is not cheap.

Due to such high costs, many choose soft roofing. In this case, it is necessary to remember about the crate, which is continuous from boards or plywood. Such a roof also needs lining carpets. Consequently, the developer, when buying building materials, will also have to pay a large amount.

A roof with two slopes is the most common option for completing the box of a private house. In its manufacture, it is important to correctly select the cross-sections of the supporting elements, securely fasten the nodes and choose the right type of construction. The truss system of a gable roof does not have great difficulties and may well be made by hand.

Classification of truss systems according to the method of support

The structure can be classified in two ways. The first of them is the method of supporting the bearing elements. The gable roof truss system of the house in this case includes the following types:

• with layered rafters;
• with hanging rafters.

Types of a gable roof with layered and hanging rafters

Roofing with the use of layered rafters involves their support at two points. The design in this case avoids the occurrence of a serious spacer. To do the installation yourself, you will need the following basic elements:

• rafter legs;
• Mauerlat;
• crossbar;
• intermediate racks and struts with a large span of load-bearing beams;
• crate and counter-crate;
• overlays persistent bars.

At the top point, the installation provides for leaning on the crossbar. The installation also provides support at the lowest point - Mauerlat. You can assemble such a structure for a house with your own hands only in two cases:

Options for assembling a layered gable roof system

1. A layered system is possible if the distance between the gables is not large. That is, such an installation is suitable for a small house with your own hands. The greatest length of the structure, which allows the construction of a wooden crossbar without additional reinforcements, is 6 m. For large spans, it will be necessary to install metal beams as a crossbar. When using a wooden beam, it will be necessary to provide intermediate racks, which are located on average every 2 meters. This can be avoided only when using glued laminated timber of a sufficiently large cross section as a crossbar. In this case, a free layout of the space becomes impossible - the racks in the middle of the room cannot be removed.
2. The second option, when it is possible to install a layered gable roof system with your own hands, is the presence of a wall in the middle of the house. The device in this case provides that the beam, on which the rafters will rest at the top point, will transfer the load to the inner wall. In this case, the supporting structure should not be confused with the partition. The partition rests on the floors, and installing the wall of the house with your own hands involves resting it directly on the foundations. Such the device will fit for buildings with sufficient width, where it makes sense to install a wall fence in the middle.

The second option is hanging rafters. They are more complex in calculation, but they allow the installation in the under-roof space of a free-plan house. The design assumes the absence of a supporting wooden or metal bar in the upper part. Installation involves supporting the rafters only at the lowest point. In the upper part, the bearing beams are securely connected to each other. Installing such a system is like a farm. The design works on thrust, so it is important to prevent excessive horizontal load on the walls of the house. You can do this by doing the following:

• the device of a monolithic belt along the edge of the walls;
• it is necessary to make a reliable fastening of the Mauerlat of a gable roof to the wall of the house with your own hands;
• to eliminate the spacer, a contraction is established.

Installation of a hanging truss system

The fight or screed becomes one of the significant elements of the gable roof of the house. It prevents the expansion of the walls under the action of thrust. The following types of fights can be distinguished:

• located at the attic floor level;
• located at the level of the attic ceiling.

It is worth noting that the second option provides less reliability, since the higher the element is mounted, the stronger the rafters have an effect on it. If the fight turns out to be too long, you need to make it stronger with your own hands. For this, additional elements of the gable roof of the house are installed - suspensions. They connect the skate to the middle of the puff, which prevents it from sagging.

The gable roof truss system with hanging rafters allows installation with pre-assembly of trusses on the ground, then raise them to the roof and fix them.

This option is only suitable if you have lifting equipment, since the finished gable roofs of the house will become too large and heavy to lift with your own hands.

Classification by type of slope

The second division can be made depending on how the ramp line is designed. The views here suggest the presence of two options:

Gable roof with broken and straight slopes

1. With straight slopes. The easiest way to do. Allows you to get the job done without any hassle. The disadvantage of this do-it-yourself roofing option is the reduction in attic space.
2. With broken slopes. Such types of roofing are more difficult to perform. It is assumed that there is a line along which the angle of inclination changes. The angle of inclination of the lower part of the slope must be made greater than that of the upper. Thus, it turns out to raise the ceiling of the attic and increase the free space. The installation of the roof is carried out with the installation of an additional crossbar at the fracture site.

These types involve a choice between them, depending on the wishes of the future owner of the building.

The main elements of the roof

The rafter system of the gable final part of the building consists of many elements. Installation should begin with a detailed study of each of them and the choice of their sections.

When installing elements under a metal tile or other coating, it implies the use of a bar with a section of 150x150 or 200x200 mm. It is this size that allows you to most optimally distribute the load. then you need to choose a method of fixing it depends on the material of the walls. There are several options:

The scheme of fastening the Mauerlat to the wall

1. Frame, timber or log walls do not require the installation of a Mauerlat. In the case of a frame building, the top framing of the walls serves as a support for the rafter legs. during the construction of fences from timber or logs, the upper crown becomes the Mauerlat. It is important to correctly fix these elements in the wall structure.
2. When used for the construction of lightweight concrete, additional reinforcement will be required. Lightweight concretes include materials such as foam concrete, cinder concrete, expanded clay concrete. They can collapse if the roof is not supported centrally on them. To evenly distribute the load, a monolithic reinforced concrete belt is poured along the edge of the walls. During work, a special wire, studs or bolts are laid in it, on which the Mauerlat will be fastened.
3. For brick means, it is possible not to provide a reinforced concrete belt. In this case, to connect with the strapping beam, a wire is inserted into the masonry, which is then wrapped around the Mauerlat and twisted. The second option - one row before the walls are cut into the masonry from the outside wooden bars impregnated with an antiseptic. Such plugs and Mauerlat are fastened with staples. It is also possible to use studs and bolts, for fixing which will require pouring a monolithic belt.

An important point is waterproofing.

When installing, it is important to provide roofing material, linokrom or waterproofing at the junction of concrete or brick with wood. This is required to prevent the wood from rotting on contact with material of a different moisture content.

After fixing the Mauerlat, rafter legs are installed. Their cross section is selected depending on the pitch of the supporting beams, their span, snow load and type of coating. When installing a frame under a metal tile with a step of 60 cm, it is recommended to follow the following recommendations, depending on the span:

• 3 m - 4x15 cm;
• 4 m - 5=15 cm;
• 5 m - 5x17.5 cm;
• 6 m - 5x20 cm.

Table of average values ​​of rafter legs

These are average values, in order to perform a more accurate calculation, it is better to contact a specialist or study additional literature.

There are two ways to fasten the rafter legs to the Mauerlat:

• with a notch;
• without her.

Fastening rafter legs to the Mauerlat with and without a notch

In the first case, they washed down on the strapping beam, in the second, a special plank is nailed to the rafters, which becomes a persistent bar. Further, for both methods, the work is performed in the same way. With the help of metal corners, the inclined beam is fixed so that it does not move relative to the design position along the Mauerlat. Additionally, nails are driven in at an angle.

Scheme of fastening rafters with wire and brackets

In addition, you will need to fasten the rafter to the wall. The implementation of this measure is provided for in the regulatory documents. You can do this in two ways:

• on brackets (suitable for wooden buildings);
• using wire twisting (a more time-consuming option, but the only one possible for stone houses).

You can perform fastening according to the norms through one leg. This is necessary for a more secure attachment of the roof to the box of the house.

If you do the work correctly, you can not worry about its condition even in the strongest winds.

Racks, ties, struts

Such elements are most often made of boards. The optimal thickness is in the range of 32-50 mm. Racks are an exception. Here you can use boards with a thickness of 50-100 mm. Fastening is carried out on studs or using support bars.

Gable roof truss system: design and nodes

The device of the truss system of a gable roof

The gable roof truss system is designed for roofing in the form of two rectangles located at a certain angle to each other in the upper part of the structure. This design is quite often used in the construction of private low-rise buildings, various buildings for domestic and household purposes. At industrial and commercial enterprises, a gable roof is installed on buildings for various purposes, which have a significant length several times greater than the width. The design contains two slopes of different lengths. On the front side, a short slope with a large angle of inclination is installed, on the back - a long one, with a smaller angle of inclination. This configuration allows the main part of atmospheric precipitation to be directed to the non-working zone of the enterprise territory.

Figure 1. Scheme of fillies.

The construction of a gable roof is one of the low-cost options that does not require significant physical effort.

It is performed relatively simply with little experience working with wood material.

Typical bearing elements of the system, specific terms

Figure 2. Scheme of the crate.

In the manufacture of details of the gable roof truss system, softwood lumber is used. Hardwood is undesirable due to its high specific gravity. Most of the elements have specific names that are understood mainly by specialists:

1. Lezhen - timber with a section of 150x150 mm, 180x180 mm. It is laid on the surface of the internal load-bearing wall. Designed for leveling the surface and distributing loads from racks.
2. The rafter leg, or rafter, is a piece of timber or thick board. The main element of the triangular roof structure, bearing the main load from snow, rain, wind and other atmospheric phenomena. The distance between the rafter legs can be from 0.6 to 1.2 m. The step size mainly depends on the plumb line of the roofing material, in some cases, the characteristics of the roofing material should be taken into account.
3. Mauerlat - a square beam with a side size of 150-180 cm. It is laid on the surface of external load-bearing walls. When installing, it must be fixed with anchor bolts or in another reliable way. Distributes the load from the rafter legs to the load-bearing walls.

All parts of a gable roof are interconnected in various ways. Previously, structures were assembled mainly using staples, nails, threaded studs. Now manufacturers of building materials offer a wide range of different brackets for assembling roofs of any configuration. Most parts are fastened with self-tapping screws of the required diameter and length, reinforced with special spikes in the brackets.

Additional elements of the rafter system

Figure 3. Scheme of an arch with three hinges.

In addition to load-bearing parts, additional reinforcing elements are used in the structures:

1. Filly (Fig. 1) - used to increase the length of the rafter legs. Are established in the lower part for the device of cornice overhang. The thickness of the filly is somewhat less than the size of the rafters.
2. Roof overhang, or cornice overhang, is a roof element protruding from the edge of the wall by about 40-50 cm. Designed to protect walls from atmospheric precipitation.
3. The ridge is an element that connects all the rafter legs of the system in the upper part. Installed in a horizontal position.
4. Sheathing (Fig. 2) - boards or bars installed for fixing the roof. They are located perpendicular to the rafter legs, additionally performing the function of their fastening. They take the main effort from the roofing material, distribute it to the rafters. For the device, it is desirable to use edged lumber. With limited funds, you can use unedged, clearing it of bark. If the roof is soft material, the crate is made solid. This option can be made from boards or plywood treated with protective materials from high humidity. When corrugated board is used, the crate is performed with a certain step, depending on the weight of the material and its design features.
5. Struts - elements made of timber or thick boards that reinforce the main structure. Distribute the force from the rafter legs to the bearing parts. The assembled structure of struts and puffs was called a farm - an enlarged part with the necessary margin of safety.
6. Racks - are made from pieces of lumber of rectangular or square section. Are established in vertical position under a descent of slopes. The load from the corner connection of the roof rafters is distributed through the posts to the internal load-bearing wall.
7. Puff - a bar or board that fastens the rafters in a hanging system. Creates a rigid triangle shape between rafter legs, compensating for sprawl.

For the manufacture of additional parts, you can use lumber with a section similar to that of load-bearing parts. In order to save money, you can calculate and purchase products of a smaller section.

Two typical ways to arrange truss systems

Figure 4. Scheme of connecting the lower ends of the parts.

The gable roof truss system can be arranged in two main ways:

• hanging rafter system;
• layered system.

The hanging system is used for buildings with a distance between the outer walls of less than 10 m, without an internal load-bearing wall in the middle of the building. In a different configuration of the building, a layered rafter structure is used.

If the building has columns located along one of the central axes, it is possible to use a combined option. Rafter legs located above the columns are mounted with emphasis on the surface of the columns, hanging rafters are installed between them.

Hanging truss system

In structures of this type, the installation of truss beams is carried out on the surface of the outer walls. The disadvantage of this method is the occurrence of force, bursting the walls. To compensate for the load, the beams are pulled together by tightening. The design takes the form of a rigid triangle that retains its shape under the influence of loads. In some cases, floor beams can play the role of puffs. Such a scheme is used when arranging an attic in the attic space.

Hanging rafters can be made in various versions:

Scheme of the reinforced structure.

1. A simple version of the arch with three hinges (Fig. 3) - the design is a rigid triangle, the two sides of which are the rafter legs. The main load creates a bending force on the parts. The force on the third side is aimed at stretching the structure, so instead of a wooden part, a steel tie can be used. The connection of the lower ends of the parts can be assembled different ways(fig. 4), tie-in beams, using wooden elements or metal brackets.
2. Reinforced structure (Fig. 5) - a gable truss system used for roofing of large industrial buildings with a distance between walls of more than 6 m. This system is not suitable for use in small residential buildings. A design feature is the distribution of the puff weight on the skate. Since it is almost impossible to find solid lumber of the required length (6 m or more), the puff is made from segments. The connection of all elements is carried out by a straight or oblique inset. The central part is called the headstock. The connection of the headstock with a tightening is performed by a collet twist with the possibility of adjusting the tension.
3. The device of an arch with a tightening in the upper part of the rafters (Fig. 6) is used for equipment in the attic space of the attic. At the same time, the tensile force in the rafter beams increases. The lower ends of the beams are attached to the Mauerlat bars. The fastening should limit the movement of the beams to the sides along the beam, but allow sliding across. This ensures uniform load distribution and stability of the entire system. Rafter beams should form an overhang.

Many variants of hanging-type systems have been developed. Most are used for relatively small buildings without load-bearing structures inside buildings. For larger buildings, a layered rafter system should be used.

Layered truss system

The main difference of this system is the installation of a vertical beam resting on an internal load-bearing wall located in the middle of the building. This design is necessary when a gable roof is installed on a building with a wall spacing of more than 10 m.

Figure 6. Arrangement of an arch with a puff at the top of the rafters.

1. A properly executed system of non-expanding rafter beams allows you to get rid of the forces that burst the walls. The surface of the slopes is subjected only to the bending force. There are 3 main options for the device of such systems. With all options, the lower ends of the rafters are attached according to the sliding support method. For insurance, an additional mount is installed between the support bar and the rafter leg.
2. You can use a steel strip, wire tie. The options differ in the method of connecting the upper ends of the rafters, docking with the ridge beam. One of the options involves laying rafters on a beam in the form of a sliding support with a cutout device. Mounting can be done using brackets or special brackets. The gable roof, arranged according to the following option, is the most popular because of the simplicity of the device. The top of the rafters can be made end-to-end or overlay with cutting grooves. The corner must be fastened with any of available ways and fix it on the skate beam. The third option involves a rigid connection of the run and rafters. For mounting on rafter legs, pieces of boards are stuffed on two sides. A large bending force is formed on the beam, but the load on the rafter beams is reduced.
3. A gable roof for a building with dimensions up to 14 m must have a reinforced truss system. One of the options for increasing strength is the installation of a strut. The part takes on the load from the rafter leg, experiencing a compressive force. To correctly select the installation position of the element, you need to measure the angle of 45-53 ° from the horizontal plane of the building. An additional support device turns an ordinary beam into a reinforced version, consisting of two spans. To install the struts, calculations are not required, you just need to fix it under the rafter, cutting out the joint angle with maximum accuracy.

The technology for installing gable roofs is simple, you can do everything yourself. Work must begin with the installation and fastening of the base to the walls, then mount the gables. It is desirable to carry out work on the manufacture of truss beams and enlargement of structures on the ground, collected items lift, install on the building, fix with temporary fasteners. After assembling and installing all the elements, you should fix the crate and proceed with the installation of the roof.

Gable roof truss system: installation and diagrams

Do-it-yourself gable roof truss system: an overview of hanging and layered structures

Rafters perform a number of significant roofing functions. They set the configuration of the future roof, perceive atmospheric loads, and hold the material. Among the rafter duties are the formation of even planes for laying the coating and providing space for the components of the roofing pie. In order for such a valuable part of the roof to flawlessly cope with the listed tasks, information about the rules and principles of its construction is needed. The information is useful both for those who are building a gable roof truss system with their own hands, and for those who decide to resort to the services of a hired team of builders.

Rafter structures for gable roofs

In the device of the truss frame for pitched roofs, wooden and metal beams are used. The starting material for the first option is a board, log, timber. The second is constructed from rolled metal: a channel, a profile pipe, an I-beam, a corner. There are combined structures with steel most loaded parts and wood elements in less critical areas.

In addition to the "iron" strength, the metal has a lot of disadvantages. These include heat engineering qualities that do not satisfy the owners of residential buildings. Disappointing need for the use of welded joints. Most often, industrial buildings are equipped with steel rafters, less often private change houses assembled from metal modules.

In the case of self-construction of truss structures for private houses, wood is a priority. It is easy to work with it, it is lighter, “warmer”, more attractive in terms of environmental criteria. In addition, nodal connections do not require a welding machine and welder skills.

Rafters - a fundamental element

The main "player" of the frame for the construction of the roof is the rafter, among the roofers called the rafter leg. Beds, braces, headstocks, girders, puffs, even Mauerlat may or may not be used depending on the architectural complexity and dimensions of the roof.

The rafters used in the construction of the gable roof frame are divided into:

• Layered rafter legs, both heels of which have reliable structural supports under them. The lower edge of the layered rafter rests on the Mauerlat or on the ceiling crown of the log house. The support for the upper edge can be a mirror analogue of an adjacent rafter or a run, which is a beam horizontally laid under the ridge. In the first case, the truss system is called spacer, in the second, non-spacer.
• hanging rafters, the top of which rests against each other, and the bottom is based on an additional beam - puff. The latter connects the two lower heels of adjacent rafter legs, resulting in a triangular module called a truss truss. The tightening dampens the tensile processes, so that only a vertically directed load acts on the walls. The design with hanging rafters, although it is spacer, does not transfer the spacer itself to the walls.

In accordance with the technological specifics of the rafter legs, the structures constructed from them are divided into layered and hanging. For structural stability, they are equipped with struts and additional racks. For the arrangement of supports for the top of the layered rafters, beds and girders are mounted. In reality, the truss structure is much more complicated than the elementary patterns described.

Note that the formation of a gable roof frame can generally be carried out without a truss structure. In such situations, the alleged planes of the slopes are formed by slegs - beams laid directly on the bearing gables. However, we are now specifically interested in the device of the gable roof truss system, and it can involve either hanging or layered rafters, or a combination of both types.

Subtleties of fastening rafter legs

The rafter system is fastened to brick, foam concrete, aerated concrete walls through the mauerlat, which in turn is fixed with anchors. Between the Mauerlat, which is a wooden frame, and the walls of these materials, a waterproofing layer of roofing material, waterproofing, etc. is necessarily laid.

The top of the brick walls is sometimes specially laid out so that something like a low parapet is obtained along the outer perimeter. So it is necessary that the Mauerlat placed inside the parapet and the walls do not burst the rafter legs.

The rafters of the frame of the roofs of wooden houses rest on the upper crown or on the ceiling beams. The connection in all cases is made by cutting and duplicated with nails, bolts, metal or wooden plates.

How to do without furious calculations?

It is highly desirable that the cross section and linear dimensions of the wooden beams be determined by the project. The designer will give clear calculation justifications for the geometric parameters of the board or beam, taking into account the entire range of loads and weather conditions. If there is no home design development master at his disposal, his path lies on the construction site of a house with a similar roof structure.

You can ignore the number of storeys of the building under construction. It is easier and more correct to find out the required dimensions from the foreman than to find them out from the owners of a shaky unauthorized construction. After all, the foreman is in the hands of documentation with a clear calculation of the loads per 1 m² of roof in a particular region.

The installation step of the rafters determines the type and weight of the roofing. The heavier it is, the smaller the distance between the rafter legs should be. For laying clay tiles, for example, the optimal distance between the rafters will be 0.6-0.7 m, and for the installation of metal tiles and profiled sheets, 1.5-2.0 m is acceptable. However, even if the step required for the correct installation of the roof is exceeded, there is a way out . This is a reinforcing counter-lattice device. True, it will increase both the weight of the roof and the construction budget. Therefore, it is better to deal with the step of the rafters before the construction of the rafter system.

Craftsmen calculate the pitch of the rafters according to the design features of the building, tritely dividing the length of the ramp into equal distances. For insulated roofs, the step between the rafters is selected based on the width of the thermal insulation boards.

Rafter structures of layered type

Rafter structures of the layered type are much simpler in execution than their hanging counterparts. A justified plus of the layered scheme is to provide full ventilation, which is directly related to the longevity of the service.

Distinctive design features:

• Mandatory presence of support under the ridge heel of the rafter leg. The role of the support can be played by a run - a wooden beam resting on racks or on the inner wall of the building, or the upper end of an adjacent rafter.
• The use of Mauerlat for the construction of a truss structure on walls made of brick or artificial stone.
• The use of additional runs and racks where the rafter legs, due to the large size of the roof, require additional support points.

The minus of the scheme is the presence of structural elements that affect the layout of the internal space of the operated attic. If the attic is cold and the organization of useful premises is not supposed to be in it, then the layered construction of the truss system for the installation of a gable roof should be preferred.

A typical sequence of work on the construction of a layered truss structure:

• First of all, we measure the height of the building, the diagonals and the horizontalness of the upper cut of the skeleton. When identifying vertical deviations of brick and concrete walls, we eliminate them with a cement-sand screed. Exceeding the heights of the log house we squeeze. By placing chips under the Mauerlat, vertical flaws can be dealt with if their magnitude is insignificant.
• The floor surface for laying the bed must also be leveled. He, the Mauerlat and the run must be clearly horizontal, but the location of the listed elements in the same plane is not necessary.
• We process all wooden parts of the structure before installation with fire retardants and antiseptic preparations.
• We lay waterproofing on concrete and brick walls for the installation of a Mauerlat.
• We lay the Mauerlat beam on the walls, measure its diagonals. If necessary, we slightly move the bars and turn the corners, trying to achieve the perfect geometry. Align the frame horizontally if necessary.
• We mount the Mauerlat frame. The splicing of the beams into a single frame is carried out by means of oblique cuts, the joints are duplicated with bolts.
• We fix the position of the Mauerlat. Fasteners are made either with brackets to wooden plugs laid in the wall ahead of time, or with anchor bolts.
• We mark the position of the bed. Its axis should recede from the Mauerlat bars at equal distances on each side. If the run will be based only on racks without lying down, the marking procedure is carried out only for these columns.
• We install the bed on a two-layer waterproofing. We fasten it to the base with anchor bolts, connect it to the inner wall with wire twists or staples.
• We mark the installation points of the rafter legs.
• We cut out racks according to uniform sizes, because our bed is set to the horizon. The height of the racks must take into account the dimensions of the section of the run and the bed.
• Installing racks. If provided by the project, we fix them with spacers.
• We lay the run on the racks. We check the geometry again, then install the brackets, metal plates, wooden mounting plates.
• We install a trial rafter board, mark the places of trimming on it. If the Mauerlat is set strictly to the horizon, there is no need to adjust the roof rafters in fact. The first board can be used as a template for making the rest.
• We mark the installation points of the rafters. Folk craftsmen for marking usually prepare a pair of slats, the length of which is equal to the gap between the rafters.
• According to the markup, we install the rafter legs and fasten them first at the bottom to the Mauerlat, then at the top to the run to each other. Every second rafter is screwed to the Mauerlat with a wire bundle. In wooden houses, the rafters are screwed to the second crown from the top row.

If the rafter system is done flawlessly, the layered boards are mounted in random order. If there is no confidence in the ideal structure, then the extreme pairs of rafters are installed first. A control twine or fishing line is stretched between them, according to which the position of the newly installed rafters is adjusted.

The installation of the truss structure is completed by installing the filly, if the length of the rafter legs does not allow the formation of an overhang of the required length. By the way, for wooden buildings, the overhang should “go beyond” the contour of the building by 50 cm. If the organization of the visor is planned, separate mini-rafters are installed under it.

Hanging truss systems

The hanging type of truss systems is a triangle. The two upper sides of the triangle are folded by a pair of rafters, and the puff connecting the lower heels serves as the base. The use of tightening allows you to neutralize the effect of the thrust, therefore, only the weight of the crate, the roof, plus, depending on the season, the weight of precipitation, acts on walls with hanging truss structures.

The specifics of hanging truss systems

Characteristic features of hanging type truss structures:

• Mandatory presence of a puff, made most often of wood, less often of metal.
• The ability to refuse the use of Mauerlat. A frame made of timber will be successfully replaced by a board laid on a two-layer waterproofing.
• Installation on the walls of ready-made closed triangles - roof trusses.

The advantages of the hanging scheme include the space under the roof free from racks, which allows you to organize an attic without pillars and partitions. There are disadvantages. The first of these is the limitation on the steepness of the slopes: their slope angle can be at least 1/6 of the span of a triangular truss, steeper roofs are strongly recommended. The second disadvantage is the need for thorough calculations for the competent device of cornice nodes.

Among other things, the angle of the truss truss will have to be set with jewelry accuracy, because. the axes of the connected components of the hanging truss system must intersect at a point, the projection of which must fall on the central axis of the Mauerlat or the lining board replacing it.

Subtleties of long-span hanging systems

Puff - the longest element of the hanging rafter structure. Over time, it, as is typical of all lumber, deforms and sags under the influence of its own weight. Owners of houses with spans of 3-5m are not too concerned about this circumstance, but owners of buildings with spans of 6 meters or more should think about installing additional parts that exclude geometric changes in tightening.

To prevent sagging in the installation scheme of the truss system for a large-span gable roof, there is a very significant component. This is a pendant called a grandmother. Most often, it is a bar attached with wooden surfs to the top of the truss truss. You should not confuse the headstock with the racks, because. its lower part should not come into contact with the puff at all. And the installation of racks as supports in hanging systems is not used.

The bottom line is that the headstock, as it were, hangs on a ridge knot, and a tightening is already attached to it with the help of bolts or nailed wooden plates. Threaded or collet type clamps are used to correct slack.

Adjustment of the tightening position can be arranged in the zone of the ridge knot, and the headstock can be rigidly connected to it with a notch. Instead of a bar in non-residential attics, reinforcement can be used to manufacture the described tightening element. It is also recommended to arrange a headstock or suspension where the puff is assembled from two bars to support the connection area.

In an improved hanging system of this type, the headstock is complemented by strut beams. The stress forces in the resulting rhombus are extinguished spontaneously due to the competent arrangement of the vector loads acting on the system. As a result, the truss system pleases with stability with a slight and not too expensive upgrade.

Hanging type for attics

In order to increase the usable space, the tightening of the rafter triangles for the attic is moved closer to the ridge. A perfectly reasonable move has additional advantages: it allows you to use puffs as the basis for filing the ceiling. It is attached to the rafters by cutting with a semi-frying pan with a duplication of a bolt. It is protected from sagging by installing a short headstock.

A noticeable drawback of the attic hanging structure is the need for accurate calculations. It is too difficult to calculate it on your own, it is better to use a ready-made project.

Which design is more cost effective?

Cost is an important argument for an independent builder. Naturally, the price of construction for both types of truss systems cannot be the same, because:

• In the construction of a layered structure for the manufacture of rafter legs, a board or beam of small section is used. Because layered rafters have two reliable supports under them, the requirements for their power are lower than in the hanging version.
• In the construction of a hanging structure, the rafters are made of thick timber. For the manufacture of puffs, a material similar in cross section is required. Even taking into account the rejection of the Mauerlat, the consumption will be significantly higher.

Saving on the grade of material will not work. For the bearing elements of both systems: rafters, purlins, beds, Mauerlat, attendants, racks, lumber of the 2nd grade is needed. For crossbars and puffs working in tension, you will need the 1st grade. In the manufacture of less responsible wooden slips, the 3rd grade can be used. Without counting, we can say that in the construction of hanging systems, expensive material is used to a greater extent.

Hanging trusses are assembled in an open area next to the object, then transported assembled upstairs. To lift weighty triangular arches from a bar, you will need equipment, for which you will have to pay rent. And the project for complex nodes of the hanging version is also worth something.

There are actually many more methods for constructing truss systems for roofs with two slopes. We have described only the basic varieties that are actually applicable for small country houses and buildings without architectural ideas. However, the information provided is sufficient to cope with the construction of a simple truss structure.

Do-it-yourself gable roof truss system: device, design, installation

Construction of houses

When building one-story houses, a roof with two slopes is very popular. This is due to the speed of construction of the structure. In this parameter, only a single-pitched roof can compete with a gable roof. In the device, a gable rafter roof is not too complicated. And you will successfully master this work on your own.

The design of the gable roof truss system

The gable roof consists of two inclined surfaces that have a rectangular shape. Thanks to this, precipitation, which is represented by rain and melt water, flows off the roof in a natural way. The gable roof has enough complex structure. It consists of such structural units: Mauerlat, rafter system, filly, ridge, roof overhang, bed, struts, puffs, crate and racks:

1. Mauerlat. This element performs the functions of transferring and distributing the load created by the rafter system on the load-bearing walls of the house. For the manufacture of Mauerlat, a beam is used, which has a square section - from 100 by 100 to 150 by 150 mm. It is better to use softwood. The beam is placed around the perimeter of the building and fixed to the outer walls. For fastening use special rods or anchors.
2. Rafter leg. Rafters form the main frame of any roof. In the case of a gable roof, they form a triangle. The rafters are responsible for the uniform transfer of loads to the Mauerlat. First of all, those that arise from precipitation, wind and the weight of the roof itself. For the manufacture of rafters, boards are used that have a section of 100 by 150 or 50 by 150 mm. Choose a rafter pitch of about 60-120 cm, depending on the type of roofing material. When using a heavy coating, place the rafter legs more often.
3. Skate. This element connects two slopes at the top of the roof. The ridge is formed after connecting all the rafter legs.
4. Filly. They act as a continuation of the rafters and form the overhang of the gable roof. It is customary to install fillies if the rafter legs are very short and do not allow an overhang to form. To make this structural unit, take a board that has a smaller section than the rafter. The use of fillies facilitates the construction of the truss system, as it allows the use of short rafters.
5. Eaves. This part of the design of the gable roof truss system is responsible for draining water from the walls during rain and at the same time preventing them from getting wet and quickly destroyed. The overhang protrudes from the wall, as a rule, by 400 mm.
6. Sill. It is located on the inner wall and serves to evenly distribute the load from the roof racks. For the manufacture of bedding, a beam is used, which has a section of 150 by 150 or 100 by 100 mm.
7. Racks. These vertical elements are responsible for transferring the load from the ridge to the interior walls. To create this element, prepare a beam that has a square section of 150 by 150 or 100 by 100 mm.
8. Struts. They are needed to transfer loads from the rafters to the load-bearing walls. Struts and puffs form a solid structure called a truss. Such a device is designed to withstand loads at large spans.
9. Puff. This structural unit, together with the rafters, forms a triangle. It does not allow the rafters to part in different directions.
10. Crate. This design consists of boards and bars. They are attached perpendicular to the rafters. Sheathing is necessary to evenly distribute the weight of the roof covering and the loads created by weather phenomena on the rafters. In addition, the crate is required to fasten the rafters together. When arranging a soft roof to create a crate, you should not use boards and bars, but moisture-resistant plywood.

Varieties of gable roof truss system

There are gable truss systems with hanging and layered rafters. Ideally, the design contains a combination of them. It is customary to install hanging-type rafters if the outer walls are located at a distance of less than 10 m. Also, there should no longer be walls between them that divide the space of a residential building. The design with hanging rafters creates a bursting force transmitted to the walls. It can be reduced if you arrange a puff made of wood or metal and place it at the base of the rafters.

At the same time, the rafters and tightening form a rigid geometric figure - a triangle. It is not able to deform under loads that are in any direction. The puff will be stronger and more powerful if it is placed higher. The floor beams act as puffs. Thanks to their use, the hanging rafter system of a gable roof acts as the basis for the arrangement of the attic floor.

Laminated rafters in their design have a support beam, which is located in the middle. It is responsible for transferring the weight of the entire roof to the intermediate column or middle wall located between the outer walls. It is recommended to install layered rafters if the outer walls are placed at a distance of more than 10 m. If there are columns instead of internal walls, you can alternate between layered and hanging type rafters.

Do-it-yourself gable truss system

The roof must be strong to withstand various loads - precipitation, gusts of wind, the weight of a person and the roofing itself, but at the same time light, so as not to put a lot of pressure on the walls of the house. A properly arranged gable rafter roof evenly distributes the load on all load-bearing walls.

Calculation of a gable roof

The choice of a gable roof slope will depend on the material you have chosen for laying on the roof and architectural requirements:

• When building a gable roof, remember that it must slope at an angle of more than 5 degrees. It happens that the slope of the roof reaches 90 °.
• For areas with heavy rainfall, and when the roofing does not fit snugly, steep slopes are made. In this situation, the angle should be 35-40 ° so that precipitation does not linger on the roof. But such an angle does not allow building a living space in the attic. The output will be a broken roof structure. It will have a flat upper part, and on the lower part there will be a sharp slope.
• In regions with strong gusts of wind, sloping roofs are equipped. If constant winds prevail in the area, then make a slope of 15-20 ° for high-quality protection of the roofing.
• It is best to choose the middle option. Equip a gable roof that is not too steep. But also the slope should not be very gentle.
• When choosing a large angle of the roof, its windage increases, and, accordingly, the price of the gable roof truss system and the crate. After all, such a slope entails an increase in the area of ​​\u200b\u200bthe roof and, accordingly, the amount of necessary material - building and roofing.

When buying materials for the construction of a gable roof, it is useful to calculate its area:

1. Find the area of ​​one slope of the structure, and then double the result.
2. Ideally, a slope is an inclined rectangle that is placed along a long load-bearing wall. To determine the area of ​​​​a slope, multiply its length by its width.
3. The length of the slope is equal to the length of the wall. In addition, the length of the ledge of the roof above the gable is added to the length. Remember that the protrusions are present on both sides.
4. The width of the slope is the length of the rafter leg. To it is added the length of the ledge of the roof above the load-bearing wall.

In order to properly design the structure, it is recommended to carry out an accurate calculation of the gable roof truss system, including determining the loads and characteristics of the rafters:

1. When erecting a roof for a standard building that has one floor, the design load on the roof will consist of two values. The first of them is the weight of the roof, the second is the load from external factors: precipitation and wind.
2. Calculate the weight of the roof by adding up the weight of each layer of the "pie" - heat-insulating, vapor barrier and waterproofing materials, truss system, battens and directly roofing material. Calculate the weight per 1 m2.
3. Increase the result by 10%. You can also take into account the correction factor. In our case, K=1.1.
4. If you plan to change the design of the roof over time and increase the angle of its inclination, then include a margin of safety in the calculation. Take immediately higher load indicators than those that you received at the time of the calculation. It is recommended to build on the value, which is 50 kg per 1 m2.
5. When calculating the load exerted by atmospheric phenomena, take into account the climatic features of the area where the building is located. In this calculation, take into account the slope of the slope. If the gable roof forms an angle of 25 degrees, then take the snow load equal to 1.
6. If the roof is equipped with a greater slope - up to 60 degrees, the correction factor reaches 1.25. Snow load for an angle greater than 60 degrees is not taken into account.
7. The rafters transfer the entire load from the created structure to the load-bearing walls. Therefore, their parameters must also be taken appropriately. Select the section and length of the rafter leg, depending on the current load on the roof and the angle of the slope. Increase the values ​​obtained by 50% to ensure a high margin of safety.

Mauerlat installation methods

The construction of any roof begins with the installation of a Mauerlat:

• If logs or timber were used to build the walls, then the upper timber will act as a Mauerlat, as shown in the photo of the gable roof truss system.
• If you used bricks to build walls, then brick the metal rods into the masonry. They must have a cut thread for attaching the Mauerlat. Install rods every 1-1.5 m. Choose rods with a diameter of at least 10 mm. Lay waterproofing between masonry and Mauerlat.
• For walls made of ceramic or foam concrete blocks, pour concrete on top. Be sure to make the layer reinforced. It should have a height of approximately 200-300 mm. Be sure to attach metal rods that are threaded to the reinforcement.
• For Mauerlat, use a beam that has a section of 15 by 15 cm. It will act as a kind of foundation for the truss system.
• Lay the Mauerlat on the top edge of the wall. Depending on its design, the Mauerlat can be laid along the outer and inner edges. Do not place it close to the very edge, as otherwise it may be torn off by the wind.
• Mauerlat is recommended to be placed on top of the waterproofing layer. To connect all the parts into one whole, use bolts and metal plates.
• To avoid sagging, make a lattice of racks, struts and a crossbar. To do this, take boards measuring 25x150 mm. The angle between the strut and the leg of the rafter should be as straight as possible.
• If using a rafter leg that is too long, install another support. She must lean on the bed. Each element is associated with two adjacent ones. As a result, a stable structure is created around the entire perimeter of the roof.

Rafter leg attachment

The best option for a gable roof truss system is a combination of sloping and hanging rafters. This design allows you to create a reliable gable roof and reduce the cost of Construction Materials. Consider the following recommendations when working:

1. Use only the highest quality wood as a material. Beams that have cracks and knots should not be used.
2. Rafters have standard sizes- 50x150x6000 mm. When the beams are longer than 6 m, it is recommended to increase the width of the board so that the beams do not break under their own weight. Take boards 180 mm wide.
3. First, make a template for the rafter leg. Attach the board to the floor beam and the end of the ridge beam. Having outlined two lines, saw off a board along them. The template is ready.
4. Cut the rafters according to this pattern. After that, do the top washed down on them.
5. Take the resulting workpiece, bring it to the floor beam to mark the lower cut in place.
6. Install all rafters. At the same time, remember that after installing one leg, you must immediately install the opposite one. So you will quickly remove the lateral loads on the ridge beam.
7. If the slope is too long, then standard boards will not be enough to make a rafter leg. In this case, you can splice two boards together. To do this, sew on them a piece of wood of a similar section. It should have a length of 1.5 - 2 meters. According to the diagram of the gable roof truss system, the joint should always be at the bottom. Under it, install an additional rack.
8. Attach the rafter leg to the ridge beam with nails. Use self-tapping screws to fasten the rafters to the floor beam. Metal mounting plates are also suitable. In addition, a few nails are added.
9. If you are building a structure exclusively from hanging rafters, then skip the next step. When erecting a structure with layered rafters, you need to think about the supports that are installed on their floor. To reduce the deflection of the rafters, correctly calculate the location of such supports.
10. If you are building a gable mansard roof, intermediate racks will become a frame for the side walls.
11. When performing this work, maintain a certain step of the beams. Set its size at the design stage.
12. After installing the rafters, attach the ridge. It is located on their upper edge. For fastening use metal corners or staples. Bolts are the most popular.

Giving structure rigidity

After installing the gable roof truss system, strengthen it using the technology below:

• For smaller buildings, such as saunas, cottages, utility buildings, and roofs with a simple hanging rafter system, connect each pair of rafters from below with a tightening and from above using a crossbar.
• For large buildings that are light at the same time, provide a lightweight roof. The walls must support it.
• If the house has a width of 6-8 m, then the structure should be tightened. Install in the middle of the support. Such racks are called grandmas. Place them at each pair of rafter legs.
• If the span of the walls reaches 10 meters, then reinforcing beams will be needed. The struts act as an additional support for the rafter legs for tightening. They are attached to each rafter - closer to the ridge or in the middle of the rafter leg. Fasten them to the bottom end of the headstock and to each other as shown in the gable roof truss video.
• In a situation with long roofs, gable beams should be relieved. This is done by installing braces. The upper end should rest against the corner of the gable. The lower one is mounted on the central floor beam. For fasteners, use a beam that has a large cross section. So you can prevent them from breaking if there are strong gusts of wind.
• In areas where winds predominate, the rafters must be resistant to such influences. Strengthen them by installing diagonal ties. Boards are nailed from the bottom of one rafter to the middle of the next.
• For greater rigidity, when creating the most critical fasteners, it is better not to use nails. Use pads and metal fasteners for this. Nails will not be able to provide high-quality fastening, since the wood can dry out after some time.

Lathing of the truss system

The final stage of the construction of the gable roof truss system is the creation of the crate. It is on it that you will lay the roofing. Carry out the work in the following sequence:

1. Select a dry timber for the crate. It should not have cracks or knots. Nail the bars on the bottom. Attach two boards near the ridge so that there are no gaps. The lathing must withstand the weight of the top roofing material and not sag under the weight of the workers.
2. If you arrange soft roof, make two layers of skin. One is sparse, the other is solid. The same applies to roll roofing. To begin with, parallel to the ridge beam, place boards that are 25 mm thick and no more than 140 mm wide. A small gap is allowed - no more than 1 cm. Lay a continuous layer on top. To do this, it is better to use roofing plywood, slats or boards of small thickness. After that, check that there are no errors left on the crate - bumps and knots. Also check that the nail heads are not sticking out.
3. Lay one layer of timber under the metal tile. It should have a section of 50 by 60 mm. Do the same when using slate or steel roofing sheets. Maintain a step between the timber, depending on the roofing you choose - from 10 to 50 cm. Hammer nails closer to the edges of the board, and not in the middle. Drive hats deep. So they will not be able to damage the roof later. If you are making a crate for a metal tile, then remember that the connection of the timber at the same level should fall on the rafters.

When you have installed and strengthened the gable roof truss system, you can start installing the roofing pie. Place a thermal insulation material between the rafters, a layer of vapor barrier and waterproofing. When using insulation in slabs, calculate in advance the pitch of the rafters for its installation. At the final stage, fasten the roofing material.

The device of the gable roof truss system, Building Portal

A gable roof or gable roof is a roof with two slopes, i.e. having 2 inclined surfaces (slopes) of a rectangular shape.

The gable roof frame, due to its design features, ideally combines ease of installation and maintenance with reliability and durability. These and many other parameters make the construction of a gable roof a practical and rational solution for private and commercial housing construction.

In this article, we will consider how to make a gable roof truss system with your own hands. For effective perception of the material, it is presented in the form of a step-by-step instruction from A to Z, from selection and calculations, to installation of a Mauerlat and a crate under the roof. Each stage is accompanied by tables, diagrams, drawings, drawings and photos.

The popularity of the roof with a house is due to a number of advantages:

• design variability;
• simplicity in calculations;
• natural flow of water;
• the integrity of the design reduces the likelihood of leaks;
• profitability;
• preservation of the useful area of ​​​​the attic or the possibility of arranging an attic;
• high maintainability;
• strength and wear resistance.

Types of gable roof

The installation of a gable roof truss system depends primarily on its design.

There are several options for gable roofs (types, types):

The most common version of the roof device due to its simplicity and reliability. Due to the symmetry, a uniform distribution of loads on the load-bearing walls and the Mauerlat is achieved. The type and thickness of the insulation do not affect the choice of material.

The cross section of the beam makes it possible to provide a margin of bearing capacity. There is no possibility of bending the rafters. Supports and spacers can be placed almost anywhere.

A clear drawback is the impossibility of arranging a full-fledged attic floor. Due to sharp corners, “blind” zones appear that are unsuitable for use.

The device of one angle more than 45° leads to a decrease in the amount of unused area. There is an opportunity to make living rooms under the roof. At the same time, the requirements for the calculation are increasing, because. the load on the walls and foundation will be distributed unevenly.

This roof design allows you to equip a full-fledged second floor under the roof.

Naturally, a simple gable truss roof differs from a broken one, not only visually. The main difficulty lies in the complexity of the calculations.

The design of the gable roof truss system

Building a roof of any complexity with your own hands involves knowledge of the purpose of the main structural elements.

The locations of the elements are shown in the photo.

• Mauerlat. Designed to distribute the load from the truss system to the load-bearing walls of the building. For the arrangement of the Mauerlat, a beam of durable wood is selected. Preferably larch, pine, oak. The cross section of the beam depends on its type - solid or glued, as well as on the estimated age of the structure. The most popular sizes are 100x100, 150x150 mm.

  Advice. For a metal truss system, the Mauerlat must also be metal. For example, a channel or an I-profile.

• rafter leg. The main element of the system. For the manufacture of rafter legs, a durable beam or log is used. The legs connected from above form a farm.

The silhouette of the roof truss determines the appearance of the structure. Examples of farms in the photo.

Rafter parameters are important. They will be discussed below.

• puff- connects the rafter legs and gives them rigidity.

• Run:

• Skate run, mounted at the junction of one rafter to another. In the future, a roof ridge will be installed on it.

• Side runs, they provide the truss with additional rigidity. Their number and size depend on the load on the system.

• Rafter rack- vertically located beam. It also takes on part of the load from the weight of the roof. In a simple gable roof, it is usually located in the center. With a significant span width - in the center and on the sides. In an asymmetrical gable roof - the installation location depends on the length of the rafters. With a sloping roof and the arrangement of one room in the attic attic, the racks are located on the sides, leaving free space for movement. If there are supposed to be two rooms, the racks are located in the center and on the sides.

The location of the rack depending on the length of the roof is shown in the figure.

• Strut. Serves as a support for the rack.

Advice. Installing the brace at an angle of 45° significantly reduces the risk of deformation from wind and snow loads.

In regions with a significant wind and snow load, not only longitudinal struts are installed (located in the same plane with the rafter pair), but also diagonal ones.

• Sill. Its purpose is to serve as a support for the rack and a place for attaching the strut.

• crate. It is intended for movement during construction works and fixing of roofing material. It is installed perpendicular to the rafter legs.

Advice. An important purpose of the crate is to redistribute the load from the roofing material to the truss system.

The presence of a drawing and a diagram indicating the location of all the listed structural elements will help in the work.

Advice. Be sure to add data on the passage of the ventilation shaft and chimney to the scheme of the gable roof truss system.

The technology of their device is determined by the type of roof.

The choice of material for rafters

When calculating the material for a gable roof, you need to choose high-quality wood without damage and wormholes. The presence of knots for beams, Mauerlat and rafters is not allowed.

For boards, there should be a minimum of knots, and they should not fall out. Wood must be durable and treated with the necessary preparations that will enhance its properties.

Advice. The length of the knot should not exceed 1/3 of the thickness of the timber.

Calculation of the truss system of a gable roof

The calculation of material parameters is an important stage, so we present the calculation algorithm step by step.

It is important to know: the entire truss system consists of many triangles, as the most rigid element. In turn, if the slopes have a different shape, i.e. are an irregular rectangle, then you need to divide it into separate components and calculate the load and the amount of materials for each. After calculations, summarize the data.

1. Calculation of the load on the truss system

The load on the rafters can be of three types:

• Permanent loads. Their action will always be felt by the truss system. Such loads include the weight of the roof, lathing, insulation, films, additional elements of the roof, finishing materials for. The weight of the roof is the sum of the weight of all its constituent elements, it is easier to take into account such a load. On average, the value of the constant load on the rafters is 40-45 kg / sq.m.

Advice. To make the margin of safety for the rafter system, it is better to add 10% to the calculation.

For reference: The weight of some roofing materials per 1 sq.m. presented in the table

Advice. It is desirable that the weight of the roofing material per 1 sq.m. roof area, did not exceed 50 kg.

• Variable loads. They operate at different times and with different strengths. Such loads include: wind load and its strength, snow load, precipitation intensity.

In fact, the roof slope is like a sail and, if you take into account the wind load, the entire roof structure can be destroyed.

The calculation is carried out according to the formula: wind load is equal to the indicator for the region, multiplied by the correction factor. These indicators are contained in the SNiP "Loads and Impacts" and are determined not only by the region, but also by the location of the house. For example, to a private house surrounded by high-rise buildings, there are fewer loads. Standing separately Vacation home or cottage experience increased wind loads.

2. Calculation of the snow load on the roof

The calculation of the roof for snow load is carried out according to the formula:

The total snow load is equal to the weight of the snow multiplied by the correction factor. The coefficient takes into account wind pressure and aerodynamic influence.

The weight of snow, which falls on 1 sq.m. roof area (according to SNiP 2.01.07-85) is in the range of 80-320 kg / sq.m.

The coefficients showing the dependence on the slope angle are shown in the photo.

Nuance. With a slope angle of more than 60 ° snow load does not affect the calculation. Since the snow will quickly slide down and will not affect the strength of the timber.

• Special loads. Accounting for such loads is carried out in places with high seismic activity, tornadoes, storm winds. For our latitudes, it is enough to make a safety margin.

Nuance. The simultaneous action of many factors causes a synergy effect. This is worth considering (see photo).

Assessment of the condition and bearing capacity of walls and foundations

It should be borne in mind that the roof has a significant weight that can harm the rest of the building.

Determination of the roof configuration:

• simple symmetrical;
• simple asymmetric;
• broken line.

How harder shape roofs, themes large quantity roof trusses and sub-rafter elements are needed to create the necessary margin of safety.

The angle of inclination of a gable roof is determined primarily by the roofing material. After all, each of them puts forward their own requirements.

• soft roof - 5-20°;
• metal tile, slate, corrugated board, ondulin - 20-45 °.

It should be noted that increasing the angle increases the area of ​​\u200b\u200bthe space under the roof, but also the amount of material. What affects the overall cost of work.

Nuance. The minimum slope angle of a gable roof must be at least 5°.

5. Calculation of the pitch of the rafters

The pitch of the rafters of a gable roof for residential buildings can be from 60 to 100 cm. The choice depends on the roofing material and the weight of the roof structure. Then the number of rafter legs is calculated by dividing the length of the slope by the distance between the rafter pairs plus 1. The resulting number determines the number of legs per slope. For the second number, you need to multiply by 2.

The length of the rafters for the attic roof is calculated using the Pythagorean theorem.

Parameter "a"(roof height) is set independently. Its value determines the possibility of arranging a dwelling under the roof, the convenience of being in the attic, the consumption of material for the construction of the roof.

Parameter "b" equal to half the width of the building.

Parameter "c" is the hypotenuse of the triangle.

Advice. To the value obtained, you need to add 60-70 cm for sawing and taking the rafter leg out of the wall.

It is worth noting that maximum length timber - 6 m.p. Therefore, if necessary, the timber for the rafters can be spliced ​​(building, joining, joining).

The method of splicing the rafters along the length is shown in the photo.

The width of the rafters for the roof depends on the distance between opposite load-bearing walls.

7. Calculation of the section of the rafters

The cross section of the gable roof rafters depends on several factors:

• load, we already wrote about it;

• type of material used. For example, a log can withstand one load, a beam - another, a glued beam - a third;

• rafter leg length;

• type of wood used in construction;

• distance between rafters (rafter pitch).

You can determine the cross section of the beam for the rafters, knowing the distance between the rafters and the length of the rafters, using the data below.

Rafter cross section - table

Advice. The larger the installation step of the rafters, the greater the load on one rafter pair. So, the cross section of the rafters needs to be increased.

Dimensions of lumber (beams and boards) for a gable truss system:

• thickness (section) of the Mauerlat - 10x10 or 15x15 cm;

• the thickness of the rafter leg and puffs is 10x15 or 10x20 cm. Sometimes a beam of 5x15 or 5x20 cm is used;

• run and strut - 5x15 or 5x20. Depending on the width of the leg;

• rack - 10x10 or 10x15;

• bed - 5x10 or 5x15 (depending on the width of the rack);

• thickness (section) of the roof lathing - 2x10, 2.5x15 (depending on the roofing material).

Types of gable roof truss system

For the considered roof structure, there are 2 options: layered and hanging rafters.

Consider each type in detail in order to make an informed choice.

hanging rafters

They are used with a roof width of not more than 6 r.m. The installation of hanging rafters is carried out by attaching the legs to the load-bearing wall and the ridge run. The design of hanging rafters is special in that the rafter legs are under the influence of a bursting force. Hanging rafters with a puff installed between the legs can reduce its influence. The puff in the truss system can be wooden or metal. Often puffs are placed at the bottom, then they play the role of load-bearing beams. It is important to ensure that the puff is securely fastened to the rafter leg. Because a bursting force is also transmitted to it.

Advice.
The higher the puff is located, the greater the strength it should have.
If the puff is not installed, the load-bearing walls can simply “disperse” from the pressure created by the truss system.

Rafters

They are used in the arrangement of roofs of any size. The design of the layered rafters provides for the presence of a bed and a rack. Lying lying parallel to the Mauerlat takes on part of the load. Thus, the rafter legs seem to be inclined towards each other and are supported by the rack. The rafter legs of the layered system work only for bending. And the ease of installation also tips the scales in their favor. The only downside is the stand.

Combined

Due to the fact that modern roofs differ in a large variety of forms and complexity of configurations, a combined type of truss system is used.

After choosing the type of truss system, you can accurately calculate the amount of materials. Record the calculation results. At the same time, professionals recommend drawing up drawings for each element of the roof.

Installation of a gable roof truss system

After the gable roof rafters are calculated, installation can begin. We break the process into stages and give a description of each of them. Get a kind step-by-step instruction, which contains additional information for each step.

1. Attaching the Mauerlat to the wall

The beam is installed along the length of the wall on which the rafters will rest.

In log cabins, the role of the Mauerlat is played by the upper crown. In buildings built of porous material (aerated concrete, foam concrete) or brick, the Mauerlat is installed along the entire length of the load-bearing wall. In other cases, it can be installed between the rafter legs.

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Since the length of the mauerlat exceeds the standard dimensions of lumber, it has to be spliced.

The connection of the Mauerlat with each other is done as shown in the figure.

How to connect the Mauerlat?

Washed down the bars is made only at an angle of 90 °. Connections are made using bolts. Nails, wire, wooden dowels are not used.

How to fix the Mauerlat?

The Mauerlat is installed on top of the wall. Mounting technology provides for several ways to mount the Mauerlat:

• strictly in the center of the bearing wall;
• offset to one side.

Advice.
Mauerlat cannot be placed closer than 5 cm to the outer edge of the wall.

To protect the beam for the Mauerlat from damage, it is laid on a layer waterproofing material, which most often acts as an ordinary roofing material.

The reliability of fastening the Mauerlat is an important aspect of construction. This is due to the fact that the roof slope is like a sail. That is, it experiences a strong wind load. Therefore, the Mauerlat must be firmly fixed to the wall.

Methods for attaching the Mauerlat to the wall and rafters

Anchor bolts. Ideal for monolithic construction.

Wooden dowels. Are used for fellings from a log and a bar. But, they are always used with additional fasteners.

Staples.

Stud or armature. It is used if the cottage is built of porous materials (aerated concrete, foam concrete).

Sliding fastening (hinged). The bundle in this way allows you to ensure the displacement of the rafter legs when the house shrinks.

Annealed wire (knitting, steel). It is used as an additional fastening in most cases.

2. Production of roof trusses or pairs

Installation is carried out in two ways:

• installation of bars directly on the roof. It is not used often, since it is problematic to perform all the work, measurements, trimming at a height. But it allows you to completely do the installation yourself;

• assembly on the ground. That is, individual elements (triangles or pairs) for the truss system can be assembled at the bottom, and then raised to the roof. The advantage of such a system is faster work at height. And the disadvantage is that the weight of the assembled roof truss structure can be significant. To lift it, you need special equipment.

Advice. Before assembling the rafter legs, you need to mark up. It is very convenient to use templates for this purpose. The truss pairs assembled according to the template will be exactly the same. To make a template, you need to take two boards, the length of each of which is equal to the length of one rafter, and are interconnected.

3. Installation of rafter legs

The collected pairs rise up and are installed on the Mauerlat. To do this, at the bottom of the rafter legs, you need to make a drink.

Advice. Since the slots on the Mauerlat will weaken it, you can only cut down on the rafter leg. To wash down was the same and fit snugly to the base, you need to use a template. It is cut out of plywood.

Methods for attaching the rafter leg are shown in the figure.

You need to start installing rafter pairs from opposite ends of the roof.

Advice. To properly install the rafter legs, it is better to use temporary struts and struts.

A twine is stretched between the fixed pairs. It will simplify the installation of subsequent rafter pairs. And also, will indicate the level of the skate.

If the rafter system is mounted directly on the roof of the house, then after installing the two extreme rafter legs, the ridge support is installed. Further, half of the rafter pairs are attached to it.

It is worth noting that the opinions of professionals differ on this issue. Some advise using a staggered mounting order, which will evenly distribute the increasing load on the walls and foundation more evenly. This order involves the installation of one rafter in a checkerboard pattern. After part of the rafter legs is installed, the missing parts of the pair are mounted. Others insist that you need to do a consistent installation of each pair. Depending on the size of the structure and the configuration of the truss, the reinforcement of the rafter legs is carried out with props and racks.

Nuance. Additional structural elements are connected by cutting. It is preferable to fix them with building brackets.

If necessary, you can lengthen the rafter leg.

Methods for splicing rafter legs are shown in the photo.

Advice. The method by which the Mauerlat is lengthened (washed down at 90 °) cannot be used in this case. This will weaken the rafter.

4. Installing the gable roof ridge

The ridge knot of the roof is made by connecting the rafter legs at the top.

Roof ridge device:

• Method without using a support bar (see fig.).

• A method using a rafter bar. Timber is needed for large roofs. In the future, it can become a support for the rack.

• The method of laying on the beam.

• A more modern version of the manufacture of the ridge knot can be considered the method shown in the photo.

• Cutting method.

After the truss system is installed, we make a major fixing of all structural elements.

5. Mounting the roof sheathing

The crate is mounted in any case, and is designed for more convenient movement along the roof during work, as well as for fixing roofing material.

The step of the lathing depends on the type of roofing material, for example:

• under the metal tile - 350 mm (the distance between the two lower boards of the crate should be 300 mm).
• under a professional flooring and slate - 440 mm.
• under the soft roof we lay a continuous crate.

Rafter system of a gable roof with an attic - video:

Conclusion

As you can see, despite the seeming simplicity, the installation of a gable roof truss system contains many pitfalls. But, based on the above recommendations, you can easily build robust design with your own hands.

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