What slope should be at the roof of the profiled sheet? Profiled sheet roofing with a minimum roof slope Minimum profiled sheet roofing slope in degrees.

Would be rafter system strong and high-quality corrugated board, then the angle of inclination is not so important! This is what many owners of private houses think when planning the construction of a roof. And if you are also one of them, we advise you to carefully read the information below. Today you will learn what is the minimum slope of a profiled sheet roof, and why it is so important to strictly comply with these standards.

What kind of roofs distinguish masters by type of slope?

1. flat roofs– when the ramp is inclined at an angle of no more than 5 degrees. We can see this option on multi-storey buildings and large outbuildings.

2. with minimal slope- from 5 to 12 degrees. Such roofs are found in the southern regions, where there is almost no rainfall, and in windy areas.

3. pitched roofs - with an angle of 15 to 25 degrees. Such roofs are less sensitive to the accumulation of precipitation. This option is most popular in the central regions of Russia.

4. steep roofs- an angle of 40 degrees or more. Steep slope is popular in construction country houses, where attic rooms are very often equipped. Such an angle requires strengthening the truss system, taking into account wind loads.

And immediately a small three-part master class on building a roof with a minimum angle of inclination:

Why do builders propose to make a minimum roof slope?

A professional master will never advise you on the minimum slope of the roof, unless there are good reasons for that. These include the following:

• Construction takes place in areas with the strongest wind loads;
• You use the most reliable brand of corrugated board that can withstand heavy loads (snowfall), or there is almost no snow in your area;
• Are you constructing a temporary roof for a house or outbuildings;
• Or everything is much simpler - you insist on a minimum slope, as you hope to save on consumption roofing material.

By the way, very often the masters in determining the angle of the roof speak not only about degrees, but also about percentages, and even about coefficients. How to understand them? Let's look at an illustration:

Is it really possible to save well on profiled sheets on a sloping roof?

Some savings, of course, are present with a low roof slope. However, gentle slopes require more overlap of materials, more expensive joint sealing, a better waterproofing membrane, and reinforcement of the truss system (if there are strong winds in the region). Thus, the savings are minimal, and the risks do not disappear.

How to calculate the angle of the roof slope yourself?

To do this, let's look at the illustration:

Roof slope and factors affecting it

There are several main factors that determine the choice of roof slope, and many secondary ones. Consider the main ones:

• Type of building and its purpose;
• Weather conditions of the area;
• Characteristics of the roofing material;
• Additional measures to strengthen and insulate the roof.

I. Type of building and its purpose

What is the minimum roof slope for corrugated board? This question is answered by the SNiP standards, which contain the recommended indicators for the regions of our country.

So, according to official data, the minimum slope of the slope for roofing with corrugated boarding of outbuildings is 8 degrees, residential buildings - 10 degrees. Such an angle allows water to pass through at the joints of the sheets and at the attachment points, and can withstand a small layer of snow (15-20 cm).

This is data on the minimum allowable slope, but there is also such a thing as the recommended minimum slope. In this case, experts call the minimum figure - 12 degrees, and the optimal - 20 degrees. Note that many construction companies they insist on just such a minimum angle, otherwise they do not give any guarantees for work. Why is that? It is these figures that allow you to evenly distribute the load on the roofing system and the load-bearing partitions of the house, do not seal the seams and fasteners additionally, do not double overlap the materials and ensure the safe convergence of precipitation.

One more important point when choosing a degree of slope - the presence of an attic. If you are planning attic room, then you need to choose a roof slope of at least 40 degrees.

II. Weather conditions of the area

1. Wind. Even from the school course of physics and geography, we can conclude that a strong wind tries to overturn a high roof, and lift a flat roof. That is why the masters advise for windy regions to choose a minimum roof slope and reliable fastening. roof frame to the base:

2. Rain. Rain is not only excess moisture that penetrates under a flat roof faster than under steep slopes. It is also the mechanical force with which drops hit the roof. The higher the slope angle, the lower the impact force of rain or hail. Note that in some cases, these weather phenomena may well deform or pierce the material through. Therefore, if you live in a region where such weather is not uncommon, then you should think about the maximum possible slope of the roof. By the way, the maximum for corrugated board is also quite sharp - up to 70 and even 75 degrees.

3. Snow. Snow is a uniform load that lingers on a low roof and can reach up to 500 kg per 1m2 (in some regions of Russia). With such a load, a roof with a slope of 8-20 degrees can simply collapse on the owners' heads. To do this, in snowy regions, experts recommend increasing the roof slope to 40-45 degrees:

Of course, there are areas where all weather disasters can happen often and even simultaneously. In this case, trusted specialists from your locality, or neighbors who know exactly how their roofs react to local vagaries of nature, will help you calculate the angle of the roof. The data on the wind and sediment load on the plane in your area, which can be found on the corresponding maps, will help in the calculations.

III. Characteristics of the roofing material

Decking is steel galvanized profiled sheets with a polymer coating. The latter makes the material resistant to corrosion and allows you not to retain precipitation with the correct slope of the slope:

IV. Additional measures for strengthening and insulating the roof

If you have firmly decided to make a minimum roof slope from corrugated board, then you should think about additional measures to strengthen the rafter system and lay high-quality waterproofing on the slopes from the inside, and on the joints - from the outside.

With a minimum roof slope with a profiled sheet, it is necessary:

• Choose the size of the rafters at least 100x200 mm and mount them in increments of at least 60 cm;
• Strengthen the attachment of the Mauerlat to the load-bearing external partitions. Mauerlat should be reinforced with threaded spiers;
• Strengthen the fastening of the rafter legs with wire, anchors and metal corners;
• Put a high-quality waterproofing membrane under the insulation;
• Mount the counter-lattice and the crate with a step of at least 40 cm. If the slope is less than 12 degrees, then it is better to make a continuous crate from high-quality moisture-resistant plywood;
• To overlap the profiled sheets on each other by at least 20 cm (best of all - in 2 waves of the sheet);
• Carefully isolate all seams and fasteners with construction sealant.

An example of mounting a profiled sheet with a minimum slope

So, let's sum up. A small roof slope is good for outbuildings, garages, houses located in regions with strong wind loads and sunny southern areas. However, nothing is impossible! If you take all the necessary measures, take into account the conditions and important factors listed above, you can build an excellent flat roof for your home. We wish you success!

Thanks to excellent performance characteristics, the profiled sheet has found wide application in both residential and industrial construction. Subject to all the required installation technologies, it can be used to make a reliable, durable and aesthetically attractive roof sheathing.

Manufacturer's recommendations: the minimum slope of the profiled sheet roof

In most cases, this material is recommended to be laid on roofs with a slope of at least 20 degrees. This rule, however, applies mainly only to residential buildings. In industrial construction, standards allow the use of a profiled sheet as a roofing material for slopes with an inclination angle of 8 degrees. But on very flat roofs industrial buildings you can only mount a special sheet - with a self-supporting profile. Although such material is quite expensive, it is sometimes used in private housing construction. When using it, the minimum slope of the roof of a residential building from a profiled sheet can be equal to 15 degrees.

Consequences of non-compliance

If, when designing a profiled roof, the requirements of SNiP regarding the minimum allowable angle of inclination of slopes are violated, the owner of the house will subsequently face such problems as:

• leaks during rain through holes for self-tapping screws;
• punching the roof with layers of snow;
• too much heat loss through the roof;
• sheets blown off by strong gusts of wind.

Many owners of suburban real estate believe that the flatter the roof, the less material is spent on it. But in fact, this is not entirely true. When arranging a flat roof, you usually have to use a very large amount (40 cm step). In addition, in this case, the sheathing material, according to the standards, is laid with a significant overlap.

The minimum of the profiled sheet, as we found out, is 15 degrees. When designing, you can choose this version of the roof. But it is better to make the roof slopes more abruptly. In this case, the sheathing will turn out to be more reliable, and the work of installing the material itself will be easier to perform. The best option the angle of inclination of the slopes when using a profiled sheet is considered to be 25-40 cm.

What should be the overlap

This indicator, therefore, depends precisely on the angle of inclination of the slopes chosen when designing the house. So:

• for an angle from 15 to 30 degrees, the overlap should be 20 cm;
• for roofs with an angle of 30 degrees or more - 15 cm.

If the minimum slope of the roof is laid down in the project, the sheathing is made from a profiled sheet with an overlap between rows in two waves. At the same time, for additional protection from the penetration of moisture, a sealant and a special sealant are used. Among other things, in this case, a solid crate should be stuffed under the profiled sheet.

Modern industry produces profiled sheets of two main varieties: wall (marked "C") and the actual roofing ("K"). Also, this material may vary in profile shape. Of course, it should be used for the roof. As for the profile, in this regard, for the sheathing of the truss system, the “wave” or “trapezium” options are usually used with a height of 25-31 mm.

The optimal sheet thickness for roofing is 0.8 mm. Sometimes a 1 mm option is also chosen for roof sheathing. Such thick material is usually purchased if the minimum slope of the roof from the profiled sheet is selected. In degrees, as we found out, this parameter is eight to fifteen. In centimeters, this will be expressed primarily in the height of the ridge. The wider the opening, the larger this indicator will be.

For a slope of a very large area, two or three rows of sheets have to be used. However, more often the roof is designed in such a way that it could be sheathed in one row. Therefore, when choosing a material, attention should also be paid to its length. Most often, a profiled sheet of 6 m is found on sale. Therefore, it is possible that it is worth designing a roof for just such a length.

How to correctly calculate the amount of material needed for roof sheathing

The roof project should include not only its own drawings, but also an estimate with all upcoming expenses. Calculating the amount of roofing material needed is not so difficult. To do this, the roof area simply needs to be divided by the area of ​​\u200b\u200bone sheet. In this case, of course, overlaps should be taken into account. Minimum slope roofs from a profiled sheet according to SNiP - 8-15 degrees. For such a sloping roof, the overlap, as already mentioned, will be 20 cm. That is, in this case, exactly 20 cm must be subtracted from the total area of ​​\u200b\u200beach sheet.

Materials should be purchased with a small margin. After all, during the installation process, some sheets may be damaged. The same applies to additional elements. This is especially true for the case when the minimum slope is selected. In this case, the permissible parameters (8-15 °) must be observed. But in any case, sheathing a flat roof will be somewhat more difficult than a steep one, since when performing this procedure, among other things, you have to work with sealants or sealant.

Laying order

Start the installation of the profiled sheet should be from the bottom edge of the roof. Fastening is carried out on self-tapping screws with special seals. The latter are fixed in the bends of the corrugated sheet waves. Before laying the actual material itself, a drain, waterproofing of the chimney and, if necessary, the lower bar of the valleys are mounted.

The sheets themselves are attached in blocks. That is, first, on the crate near the ridge, the first one is fixed on the self-tapping screw. Why is the second sheet attached in the same way. Then it is fixed with screws to the first. The third sheet is mounted in the same way. Then the entire block is completely aligned with the cornice and finally fixed.

At the final stage of roof sheathing, a ridge, valleys, and a pipe apron are mounted. If necessary, snow guards are installed.

You need to lift profiled sheets to the roof one at a time. The metal shavings that appear when screwing in the screws should be immediately swept away with a brush. Otherwise, the polymer layer may be damaged, which will lead to a reduction in the life of the roof. Walking on the roof during work should be done in shoes with soft soles. If during installation the polymer layer of the profiled sheets is nevertheless scratched, the damaged areas must be immediately treated with a special compound. The minimum slope of self-supporting corrugated board is 8 degrees. For such a flat roof, compliance with the above recommendations is especially important. Indeed, with a small slope, the roof will have more than a serious load.

Sheets should be fastened to the crate only using special self-tapping screws with a gasket. Rivets or nails should not be used for this purpose. Self-tapping screws should not be screwed in too tightly.

Instead of a conclusion

Thus, we have found out what is the minimum slope of the roof from the profiled sheet. Calculations when drafting such a roof are best done taking into account the length and width of the sheet. In this case, the material does not have to be cut. And consequently, in the end, there will be less waste, and the roof itself will turn out to be much more reliable and durable.

An important role in the construction of a reliable and durable building is the design stage. If we talk about the roof, it is important to choose the right roof slope from corrugated board. It's not just a matter of personal preference and aesthetics. The size of the attic or attic, the presence or absence of problems with snow accumulation and resistance to wind loads depend on the angle of the roof. In order to determine the slope of the roof, it is important to consider many factors.

Some believe that the angle of inclination is associated only with the desire of the customer and the architectural idea. In fact, there are two groups of factors on which the minimum slope depends:

• Climatic conditions.
• Features of roofing material.

climate factor

There are several climate features that can significantly affect the angle of inclination:

The dependence of the angle of inclination on the roofing material

Obviously, for areas with heavy rain and snow, you need to make a roof at a large angle, and in areas with strong winds - with a minimum angle.

The choice of the minimum slope is also influenced by the characteristics of the roofing material. Each of them creates its own bottom bar for the corner of the roof. Climatic factors can increase this value, however, it is not worth making the roof more gentle than the material suggests.

• Ondulin. The minimum ramp slope is 6°.
• Soft tiles. Minimum 11° tilt.
• Decking. Not less than 12 °, otherwise it will be necessary to deal with gluing the joints of the profiled sheet.
• Metal tile. The minimum slope value is 14°.
• Roll materials in two layers - 15°. If a three-layer coating is used, it is possible to make the roof completely flat (2-5 °).

Various roofing materials

SNiP requirements

Slate, tiles and other piece materials. The minimum slope value is 22°.

According to the requirements of SNiP, for a roof made of corrugated board, the minimum allowable threshold is 8 °, however, it is only valid for outbuildings and industrial buildings. The roof angle of corrugated board for residential buildings is at least 10 °. However, construction companies only provide a guarantee for structures with a slope of 12 ° or more. The maximum tilt angle can even be 70° or more.

However, it is worth remembering that the smaller the height of the roof and, accordingly, the angle of the slope, the smaller the distance you need to make between the boards of the crate. As you can see from the table below, a roof with a slight slope requires a continuous batten.

SNiP requirements

Advantages and disadvantages of the minimum angle of inclination

Why is there even a question about the minimum allowable rate for a gable and pitched roof? What are the advantages of low structures? The following are some of their advantages:

• Reducing the consumption of roofing material. If the roof is high, it needs a more massive truss system. By reducing the slope angle, you can reduce the cost of the entire structure. However, it is worth considering that the overlap of sheets will be greater for low roofs.
• Roofing safety.
• Shed roofs are devoid of a ridge, and hence the entire scope of work with it.

In addition to the advantages, a low roof has a number of disadvantages:

• Slow water flow, which means a high probability of leaks and damage to the roofing pie. To do this, the sheets in the places of overlap must be sealed.
• High snow load on the roof. In some cases, with heavy snowfalls, it will be necessary to independently clean the roof from the profiled sheet from snow.
• Inability to equip a residential attic.

Calculation of the angle of inclination

Taking into account all of the above factors, you should decide which angle of inclination will be optimal for a particular situation. First of all, if you are going to build a house, you need to look at the angle of inclination of the roof of the neighbors, because the climatic features in the same area are the same.

It is also important to determine how the attic space will be used. If you need to create one or more living rooms, then the roof height will be greater than the minimum allowable.

There are several types of roofs from a professional sheet:

• Low-slope (14° and less). The vertical overlap of the material is 20 cm, and the joint is made in three waves.
• Medium slope (15-30°). The vertical overlap is 15-20 cm and the overlap is 1 or 2 waves.
• Steep (30° and above). The minimum overlap is 10-15 cm, and the overlap is in one wave.

As you can see, the slope of the roof also affects the consumption of roofing material. If you take into account all building codes and rules, as well as correctly determine the snow and wind loads, you can create the optimal angle of inclination of the roof for the building under construction.

It is important to understand that if a shed roof is present in the house, then one wall will be much higher than the other.

This leads to an increase in the consumption of building materials..

Before proceeding with the calculation of the slope of the roof, it is necessary to understand the degree of impact on. There are two types of loads - dynamic and constant..

To permanent loads include those which will always affect the roofing, regardless of the time of year. This includes the chimney, the antenna, the weight of the roof itself, etc.

As for dynamic loads, then these are non-constant values, i.e. weight, which affects the roof from time to time. Such an impact can be exerted by the weight of a person who periodically visits the roof to carry out any work, the weight of snow masses and hail, the effect of wind, etc.

If the slope of the roof is 30 0, then the snow force will be 50 kilograms per square meter. If you increase the angle of a shed roof to 45 0, then most likely the snow will not linger on the roof.

That's why, this value should be chosen based on the region of residence, i.e. depending on the amount of precipitation.

At the same time, if you want the snow to come off the roofing on its own (at least some part of it), then the minimum slope value should be 10 0 . The maximum value is 60 0 .

Be that as it may, the owners of houses with shed roofs every year carry out self-cleaning of the roof from snow to reduce the load on the roof.

Wind loads

The design of a shed roof is such that it is always made low to the leeward side in order to reduce the load from the wind.

Combined loads

Many people ignore this circumstance, which often leads to unpleasant situations. This type of load represents the maximum impact, which is on the roofing at any time.

It is necessary to provide for the critical load, consisting of permanent and dynamic actions, that the roofs can withstand.

Imagine a situation when there is a snow storm outside, i.e. the roof is affected simultaneously by a strong wind and a mass of snow. In addition, a person has to climb onto the roof to fix the antenna or he has to pick up a toolbox, it doesn’t matter.

It turns out that in addition to snow and wind, the weight of the human body is added. If this fact is not taken into account, then the roof may not withstand.

The dependence of the slope on the choice of roofing material

In addition to various atmospheric phenomena, the roofing that a person uses in this particular case will affect the slope.

Here are the minimum values ​​for various materials:

• , or any other piece material can be used on the roof the minimum slope value of which is 22 0.
• If you apply roll materials , then the number of layers matters. A two-layer coating will require at least 15 0, and if the material will spread in three layers, then from 2 to 5 0 will suffice.
• If used, then the minimum angle of inclination should be 12 0. If this value is less, then additional work will be required in the form of gluing joints for better sealing.
• The angle at is 14 0.
• Angle at equals 6 0.
• will require at least 11 0 tilt.

ATTENTION!

If you intend to install a shed roof, then not every roofing material you like may be suitable for you.

This means that if the slope of your roof is less than the minimum parameter characteristic of a particular material, then its use should be abandoned.

The angle of inclination depending on the roofing

How to measure the pitch of a pitched roof

We have already said that with shed roofs, the height of the walls will be different. That is why, the slope of a shed roof will be formed at the time of the construction of the walls themselves, on which the roof will be installed in the future.

If there is a lot of snow in your area, then the values ​​should be 45-60 0 . If you are in the temperate zone, then the parameters will be as follows - 5-60 0 . Of course, the minimum angle of inclination must also be taken into account, depending on the material used.

Lwalls = Llength * tgQ,

where Walls - is the height of the pediment;

Llength — is the length of the wall;

Q- is the angle of inclination.

It is also necessary to take into account the length of the rafters. It is calculated according to the following formula:

Lrafters = Lwalls / sinQ.

The values ​​of the sine and cotangent should be taken from this table:

Here is an example calculation. Let's say we use ordinary tiles, so the minimum angle of inclination is 22 0 . We take for calculation 25 0 - the value of Q.

The length of the wall is 7 meters, i.e. Llength = 7m.

Lwalls = 7 meters * tg25 = 7 * 0.47 = 3.29 meters.

L rafters = 3.29 / sin25 = 3.29 / 0.42 = 7.83 meters.

Minimum angle of inclination of a pitched roof

For the calculation of the minimum slope of a pitched roof rainfall directly affects, which may be different for each region.

If you live in a "snowy" area, then the shed roof should be steep enough, i.e. within 45 0 .

In this case, the snow will not linger on the roof, which will significantly reduce the load on the roof.

If it doesn't snow heavily in your area, then 25 0 is sufficient.

The situation is opposite in those regions where strong winds are observed.. Here it is necessary to build roofs with a slight slope so that the wind load is minimal.

Also a big role in choosing the minimum angle of inclination is played by the type of roofing material, which we talked about a little earlier. You can read more about the minimum angle and its calculation.

Minimum Angle

The optimal angle of inclination of a shed roof made of corrugated board

Decking is a rather "harmful" material, because it has many layers with different wave sizes, as well as the thickness of the material itself.

According to SNiP, the minimum slope for residential premises, the roof of which is covered with corrugated board, is 12 degrees. According to the same rules, the optimal parameter for this slope should be 20 degrees.

For a long time, shed roofs were considered the lot of garages or various non-residential premises but recently the situation has changed. Many note the fact that when choosing this type of roof, the interior design of the room becomes more original, albeit more troublesome in terms of decoration.

But this does not stop those who appreciate in their home not only reliability, but also an attractive appearance.

Optimal Angle

In contact with

It may seem to an ignorant person that the angle of inclination of the roof from corrugated board is chosen by the architect solely for aesthetic reasons. But this is far from true. In fact, the slope of the corrugated roof is one of the most important characteristics roofing system, and when choosing it, you need to take into account a lot of initial data.

Factors affecting the slope of the corrugated roof

One of the main factors that directly determines the slope of the profiled sheet are climatic features of the area in which the house under construction is located. First of all it is:

1. The height of the snow cover;
2. The amount of precipitation that falls as rain;
3. Strength and prevailing wind direction.

What is the importance of the angle of inclination of the roof from corrugated board is easy to see by considering, for example, the influence of the height of the snow cover on it.

Unlike rainwater, which runs off the roof very quickly, snow can linger on it for a long time. It is easy to imagine how much load the roof must withstand if the level of snow cover in some regions can be one meter or more. The greater the angle of inclination of the roof, the more difficult it is for the snow mass to linger on it, and with a certain thickness of the cover, snow from a steep roof will inevitably slide under its own weight.

When choosing a roof slope from corrugated board, it is necessary to take into account the characteristics of the material chosen for the roof. For example, a load-bearing corrugated sheet with a large wave height can be used even on flat roofs of shopping centers, while a wall or universal profile can only be used on roofs with a large slope.

When using any coating, it must be borne in mind that if the slopes are too small, water will not have time to drain from the roof and may seep in at the joints of the roofing. The minimum slope for a profiled sheet, at which this will not happen and you can do without additional sealing measures, is 12 °. If the angle of the roof slope from corrugated board is less than this value, then the overlap between the sheets must be additionally sealed with roofing sealant.

In addition, a small slope of a profiled sheet roof will require the use of a more expensive profile with a greater bearing capacity due to an increase in the load on the roof. The consumption of material will also increase, since the smaller the slope of the profiled sheet roof, the greater the overlap of the sheets is required, especially when it comes to vertical joints.

Among other things, for roofs with a slight slope, the truss system is many times more difficult, since it must withstand more weight. In particular, the figure above shows how the slope of a shed corrugated roof affects the design of the rafters. As you can see, with a decrease in the angle of inclination, a lot of additional elements appear, whose task is to redistribute the load from rafter leg and provide the necessary support to the main elements.

The step of the lathing and the amount of overlap of the sheets, depending on the slope of the roof from the corrugated board

As mentioned above, the minimum slope of the roof from a profiled sheet, in which there is no need to additionally seal the places of vertical overlaps, is 12 °. If the slope of the roof is between 12° and 14°, sealant is no longer required, but there remains a need for an increased size of this overlap. The slope for corrugated board is considered to be optimal from 15 ° to 30 °.

The table below shows the required overlap for corrugated boarding, the angle of inclination of the roof is of decisive importance and can be in one of the specified gaps.

The consumption of materials required for the installation of the roofing system directly depends on the angle of the roof slope from the profiled sheet. At large angles of inclination, the length of the rafters increases, but at the same time, additional struts are not required. In this case, the consumption of the corrugated board itself also increases, but its own bearing capacity is used more efficiently, therefore, a cheaper corrugated board with a lower wave height can be used.

In addition, the greater the angle of inclination of the corrugated roof, the greater the pitch of the crate and the lower the consumption of lumber. Also, the frequency of the crate is highly dependent on the brand of profiled sheet. For example, if for a profiled sheet C-21 at an angle greater than 15 °, the pitch of the crate should be equal to 650 mm, while for NS-44 at the same angle - already 1000 mm.

For the bearing profiled sheet, this gap is already 3-4 meters, and there is no separation according to the angle of the roof. There is only a minimum roof slope of corrugated board, equal to 8 °. Roofs with a smaller angle are already considered flat, so they have different requirements.

When calculating the amount of materials, it is necessary to take into account the amount of overlap of corrugated sheets, which also depends on the angle of the roof.

Minimum slope of a corrugated roof

It has already been mentioned several times above what the minimum slope for corrugated board can be, depending on the situation. Without the need for sealing joints - this is 12 °, for a bearing profiled sheet, with a corrugation height above 60 - 8 °. In principle, there is no maximum angle for this material - you can install it at least at an angle of 70 °, if the climate in your area allows it.

In addition, even 8 ° is a certain convention, since the corrugated board is great for the device. flat roofs. Although in this case the principle of manufacturing the roof changes - in particular, the profiled sheet in this case is at the bottom of the roofing pie, playing the role of overlap.

If you need a classic roof, then you can calculate the minimum roof slope from corrugated board, knowing the maximum snow loads in the region. In particular, in Yakutsk, the snow load reaches 55 kgf / m², and therefore it is simply impractical to build individual residential buildings with a low roof slope, while in the southern regions there is no such problem.

Calculation of the roof slope from corrugated board

When calculating the slope of a corrugated roof, four components must be taken into account:

• The weight of the insulation, battens, counter battens and other layers of the roofing pie;
• The weight of the roofing itself;
• Snow load for your region;
• Wind load for your region.

Suppose that we will cover the roof with a profiled sheet C21-1000-0.6. Weight square meter corrugated board of this brand is 5.4 kg. We will use basalt slabs with a thickness of 100 mm and a specific density of 150 kg/m³ as thermal insulation. Therefore, the mass of 1 m² of insulation will be 15 kg. For the crate, we use a beam of 200 × 200 mm made of pine with a step of 650 mm, so the mass of 1 m² of the crate will be 28.3 kg. We take the mass of the remaining components equal to 3 kg/m².

Thus, the mass of the entire roofing pie is equal to: 5.4+15+28.3+3=51.7 kg/m². We multiply the resulting value by a factor of 1.1 in order to provide the possibility of changing some materials of the roofing cake. In total, the total mass of 1 m² of roofing is 56.87 kg/m².

Now you need to calculate the allowable slope based on the existing snow and wind loads. Let's assume that the house is built in the Novgorod region. It belongs to the III snow region, which can be determined using the map presented above.

So, our snow load is 180 kg/m². However, it must be taken into account with a correction factor µ, which depends on the angle of inclination of the roof:

• If the slope is minimal - the angle of the roof from the profiled sheet is less than 25 °, then the value of the correction factor is taken equal to 1;
• If the angle of inclination of the roof from corrugated board is from 25 ° to 60 °, then µ=(60°-α) (60°-25°), where α - desired slope of the roof;
• If the angle of inclination of the roof from corrugated board is more than 60 °, then µ is equal to 0, that is, the snow load is not taken into account when calculating the roof.

The wind load must be taken into account when calculating the angle of inclination. The Novgorod region belongs to the Ia wind region, where, as can be seen from the map below, the normal load is 23 kg/m².

The load acting directly on the roof is calculated using the following formula:

W=Wn Kh C

Here wn— normal load for the selected region, Kh is the coefficient taking into account the height of the building, and FROM- aerodynamic coefficient, which can range from -1.8 to 0.8, depending on the slope of the roof. Since it is quite difficult to calculate it, for our formula we will take the largest - 0.8, which will simplify the calculations in the direction of greater roof strength.

So, suppose that our house is in an open area and has a height of more than 5 meters, then Kh will be equal to 1, and the wind load will be 23 1 0.8=18.4 kg/m².

Thus, taking into account the mass of the roofing cake and the influence of the wind, the load on the roof will be equal to 56.87+18.4=75.27 kg/m². Since the ultimate bearing capacity of the profiled sheet C21-1000-0.6 with a support step of 1.8 m and using the second support scheme is equal to 253 kg/m², it is necessary to choose such a slope of the roof from the profiled sheet so that the load calculated by us, taking into account the snow, is less than this value.

Insofar as 75.27+180=255.27 kg/m², which is obviously more than 253 kg/m², the slope of the corrugated roof in our case cannot be less than 25 °. Since making an angle greater than 60° is also impractical, we find that the value we need is in the range from 25° to 60° - that is µ must be calculated using the formula.

We calculate the minimum slope for corrugated roofing C21 under our conditions:

180 (60-α) (60-25)+75.27=253

Solving this simple equation, we get that α=25.441°. Thus, the permissible minimum slope of the roof from the profiled sheet with the parameters we have set will be 26 °. For greater reliability, a building located in these conditions and having the specified roofing cake, it is better to provide a roof with a slope of 30 °. Although you can stop at the minimum value, given that in the previous steps of calculating the slope of the roof from corrugated board, multiplying factors were used several times.

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