Construction of a roof from corrugated sheets with a minimum slope. How to determine the angle of inclination of the roof - rules and nuances of calculations What angle should the roof have

What is affected by the angle of the roof?

Roof construction is final stage construction of a house. But no less important than building walls. After all, the roof protects our home from bad weather, and the aesthetic side of our home depends a lot on the type of roof.

It just so happens, but flat roofs in our country can only be found on high-rise buildings. Cottages and private houses are crowned with pitched roofs. And builders consider the angle of the roof to be one of the main calculation indicators when building a house. Let's look at how to correctly calculate this indicator, what it depends on and how it affects the construction of the roof as a whole.

Types of roofs and their dependence on the angle of inclination

Depending on the roof structure, there are several types of roofs:

1. Single pitch roof. The roof is inclined plane, which lies on walls of different heights. Any material is suitable for such a roof.
2. Gable roof. This is a fairly reliable and easy to install roof. Consists of two slopes. You can also choose absolutely any material for the roof.
3. Tent roof. The roof is a structure in which several isosceles triangles close at one point with their vertices. The rafter system of such a roof is quite complex, but Supplies it will require a minimum.
4. Hip roof. It has four slopes (two triangular and two trapezoidal). The roof tops have been cut off. The roof structure is very complex, but very economical in terms of material consumption.
5. Vaulted ceiling. Such roofs are made only of brick or stone. And since they are very difficult, today in individual construction almost never used
6. Multi-gable roofs. A very complex but beautiful configuration of many junctions and ribs.

So, a roof is considered pitched if the roof slope angle exceeds 10 degrees.

There are exploited and non-exploited roofs.

An unused roof is when there is almost no space between the roof itself and the upper ceiling, or this space is intended for technical purposes. Such roofs can be flat roofs with a slope angle of 2 to 7 degrees. In such roofs, the height of the space between the roof and the ceiling is no more than one and a half meters.

It is profitable to build flat roofs. Minimum costs for materials and labor. The wind won't blow it. Again, you can equip an additional seating area. IN Lately It is very popular to lay a green roof on such roofs. But precipitation can ruin such a roof. Therefore, it is not profitable to make completely flat roofs. Precipitation will pool in the surface of the roof and destroy it.

In order to create a natural outflow of water, a layer of ceramite is poured onto flat roofs at a certain slope.

Pitched roofs allow you to use the space under the roof for household needs - an attic, an attic, or even equip them with careful insulation and living rooms.

Factors on which the roof pitch angle most depends

The main factors influencing the slope of the roof include:

• Natural factors. The angle of the roof depends on the climate of the area where construction will take place. The wind puts a huge strain on roofing roofs and the rafter system as a whole. A slight increase in the slope angle (by about 30 degrees) increases the wind load by almost 5 times. But a slight angle can also play into the hands of the elements. This will make it easier for him to get into the roof through the joints of the covering and easily tear off the roof. Precipitation can also have a destructive effect on the performance characteristics of the roof. But with the help of a well-chosen slope, you can avoid these troubles.

Remember that the maximum snow load on the roof of the roof is achieved by maintaining a roof slope of 30 degrees. And at 45 degrees, snow and rain do not linger on the roof at all.

Thus, it is obvious that if you are going to build a house in a region where precipitation is very frequent, then a roof angle of 45 degrees is just right. But if there is not so much precipitation, but the wind blows all year round, then best option– roof with a slope of 30 degrees.

How to calculate the slope angle

How to determine the roof slope that will be optimal for your new home?

Remember that the greater the angle of the roof, the more costs you will incur for construction work.

The slope is calculated as the ratio of the size of the ridge to half the width of the building and multiplied by 100. professional builders In case of calculating roof slope indicators, there are instructions and calculations. Most of them use calculation matrices and special graphs. You can get acquainted with them on the World Wide Web.

The influence of the roof slope on the choice of roofing material (and not only)

An ideal roof that would suit all regions and roofing materials has not yet been invented.

So, the magnitude of the slope was calculated. Now we select the roofing material. Slate and tiles are suitable for roofs with an angle of more than 20 degrees. If the slope is smaller, then water will run into the joints and snow will get clogged, which means the service life of the roof itself will decrease.

Roll materials bitumen-based is used when covering flat roofs or roof slopes that exceed 30 degrees. At high level When such roofs are heated by the sun and with a greater slope, the roof can simply slide down.

Metal profiles and metal tiles are used on roofs with a slope of at least 10 degrees.

Here is a list of the most common roofing materials:

1. Roof tiles. Today it is almost wildly popular. Exists a large number of varieties of this material. Such roofs are easy to repair. But to give finances for this material it will take a lot. But this material is very durable. Its service life can be calculated not only in decades, but also in centuries.
2. Roof panels. Such panels are manufactured directly at factories and in their final form represent almost finished roof. The panels immediately contain several layers - both thermal insulation and vapor barrier and the slab itself. Installing such plates is very simple. No special equipment needed. The panels are attached to each other with a special tape. But such material is very expensive.
3. Metal profile. Galvanized steel sheets. Quite light and durable material. Does not rust and is environmentally friendly. Today you can choose any color and size and direction of the waves. Manufacturers provide a guarantee for this material for a period of 75 years.
4. Piece materials from wood, such as shingles, shavings and shingles. As a rule, such materials in modern construction no one uses it anymore. This material is not durable, can rot, microorganisms multiply on nm and is easily flammable.
5. Slate. This material is already for a long time remains reliable in operation, easy to install and inexpensive to purchase. Moisture-resistant, frost-resistant, fireproof. Yes and appearance Today manufacturers have improved. You can choose slate of any desired color.

When choosing a roofing material, remember that the denser its structure, the lower the roof slope should be.

When using metal profile sheets and metal tiles on flat roofs, it is recommended to seal the joints with moisture-resistant and frost-resistant sealant. And also the size of the overlap of sheets when installing a roof made of these materials also depends on the angle of inclination of the roof. The steeper the roof, the less overlap there is. This also applies to slate.

When installing the roof, do not forget about ventilation of the space under it. Pitched roofs It is also necessary to equip it with a drainage system.

Thus, we can conclude that the angle of the roof is a very important indicator. Not only the quality of work depends on it, but also the service life of the roof itself. The main thing is to correctly calculate the value, choose the right roof structure, high-quality roofing material and a good team of workers. And, of course, not all of this will require a large budget. Good luck with your construction!

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The foundation and roof are the two most important and difficult to calculate architectural elements of any building. Roof load-bearing elements – rafter system, and its performance largely depends on the angle of inclination of the slopes. Ordinary developers choose the optimal roof angle based on different criteria than designers.

They are not entirely interested in calculations of the strength of load-bearing units; they are of little interest in the influence of the angle of inclination gable roof on the cost and complexity of the rafter system, etc.

What do ordinary developers pay attention to?

These wishes are taken into account by architects during the design and calculation of rafter system elements. But to these are added a fairly large number of purely engineering factors that have a decisive influence when calculating the parameters of the rafter system. And the angle of inclination of the slopes is not the only one among them; all values ​​depend on each other and cannot but be taken into account when developing the project.

How designers choose the optimal angle

Calculations are made based on SNiP 2.01.07-85. The posted standards are used during calculations taking into account permanent, temporary and special loads and their various combinations.

SNiP 2.01.07-85. The PDF file will open in a new tab.

What loads are taken into account when determining the roof pitch angle?

Loads are divided into several categories depending on the duration of their impact: long-term, short-term and special.

1. Long-term (constant) loads on the rafter system. These include the weight of roofing materials, insulation, wooden elements truss structure. This category should include loads arising due to thermal expansion and changes linear dimensions due to changes in the relative humidity of lumber. Standard temperature changes are determined using formulas separately for heated and unheated premises. The weight of the snow cover is also considered a long-term load on the rafter system and is necessarily taken into account when determining the optimal angle of inclination rafter legs.

   

   

2. Short-term. The rafter system is influenced by the weight of workers, stored building materials, the weight of special equipment and tools used during construction, and wind loads.

   

3. Special loads. Efforts arising during natural disasters, earthquakes, explosions, with a sharp loss of the load-bearing capacity of one or more loaded nodes of the rafter system.

   

   Special stresses include earthquakes and natural disasters

When determining the roof slope angle, the maximum possible combination of loads is taken into account. Both of these parameters affect the thickness and length of the rafter legs. The calculation of the rafter system and the angle of inclination of the slopes is done according to limit states, taking into account all unfavorable factors.

The maximum deflections and movements of the rafter legs are regulated regardless of their linear dimensions and should not lead to partial depressurization of the roof. The following conditions apply to all types of roofs, regardless of the angle of inclination:

• must be guaranteed safe operation buildings;
• the integrity of the structure cannot be compromised even during short-term peak loads;
• the appearance of the roof should not change throughout the entire period of operation.

Moreover, each requirement must be fulfilled regardless of the others. The maximum deflection values ​​of the rafters are limited taking into account performance characteristics roofing materials. If standard values do not have a noticeable effect on the appearance, they are not adjusted.

Practical advice. Much easier integrity roofing pie roofs are provided not by increasing the strength of the rafter system, but by using special structural compensators.

The slope of a metal tile roof must correspond to acceptable values, otherwise the roof will not be able to successfully withstand operational loads.

Technological features of metal tiles

The high popularity of metal tiles in private housing construction is explained by its unique characteristics:

1. Light weight (5-7 kg/m2). This material allows you to equip roofs with complex geometric shapes, does not require additional reinforcement of the rafter system when changing the roofing, and does not place a high load on building structures and the foundation of the structure.
2. Simple installation technology allows non-professionals to install the roofing; no special equipment is required for the job.
3. Wide range color solutions makes it possible to choose a shade of roofing that is in harmony with the overall appearance of the house.
4. Metal tiles, made of steel sheet with a thickness of 0.4 - 0.7 mm, can withstand significant loads due to the presence of a profile.
5. The metal is reliably protected from corrosion thanks to galvanization and an additional outer layer made of polymers with different physical and technical properties.

Modern roofing materials are subject to high demands regarding their functional and decorative characteristics, since the roof must provide reliable protection buildings from external influences and look aesthetically pleasing.

Metal tiles attract consumers with a combination of durability, performance parameters and relatively affordable cost. However, the physical capabilities of this roofing cover impose some restrictions on its use.

When choosing metal tiles when designing a roof, you should take into account such a parameter as the minimum permissible slope angle for installation of this type of covering.

From such an indicator as minimum angle roof slope, depends:

• the possibility of using one or another roofing material;
• design features of the rafter system;
• the ability to withstand the snow load characteristic of the region;
• the ability to effectively (in full, in short time) remove sediment from the roof surface.

The minimum slope of a metal tile roof is quite low due to the rigidity of the profiled steel sheets, as well as the low surface roughness, which is provided by a protective polymer coating. Such a roof can quite successfully withstand precipitation.

Factors influencing the choice of slope angle

In fact, there are no standardized slope angles for metal tile roofing. The minimum slope of slopes with this coating is affected by whole line factors that should be taken into account during the design process of a structure.

The choice of the minimum slope of the designed roof is influenced by the presence of heating pipes, as well as the thermal insulation of the house itself and the roofing pie. If the roof is not insulated enough, significant heat loss occurs through the roof. This means that snow falling on it melts and accumulates more slowly, as moisture flows down. Having provided additional thermal insulation a roof made according to the project can reduce heat loss, but at the same time snow on the roof will begin to accumulate more actively. If the slope was calculated before thermal insulation, then there is a possibility that the roofing will not be able to withstand increased snow loads.

Factors influencing the choice of slope include the amount of rain moisture. It is best if the slopes are located at an angle of at least 22 degrees. Metal roofing with a lower slope must be installed using a sealant, which will help prevent moisture from seeping into the roofing pie at the joints.

The shape of the roof should also be taken into account. Recommended tilt angle pitched roof is 20 - 30 degrees, gable - 20-45 degrees.

Minimum slope angle

According to the requirements of SNiP, if the length of the slope is 6 meters, the minimum permissible slope angle of a metal tile roof is 14 degrees. This parameter is calculated based on the average strength of the material, its ability to withstand high loads. However, when designing a roofing system, you should pay attention to the recommendations of the manufacturer of the selected roofing material.

In most cases, manufacturers indicate that the minimum slope for metal tiles should be 12 degrees. Some companies produce material suitable for installation on roofs with slopes of 11 degrees. Changing this parameter downward was made possible by improving technical characteristics a number of metal tile models: it has increased rigidity and is equipped with a smoother and slippery coating.

It is worth noting that metal tile roofing with a minimum angle of inclination can only be used in certain climatic conditions, that is, in regions where large amounts of rain and snow do not fall. A small slope angle allows the roof to perfectly withstand wind loads, but significantly increases snow loads, since the snow does not roll under own weight.

A roof made of metal tiles with a minimum angle of inclination is most relevant in areas characterized by a large number of sunny days in a year. Such a roof has a smaller area, due to which it heats up significantly less, and this has a beneficial effect on the microclimate inside the house. The minimum angle of inclination makes it possible to save money on materials for the construction of the rafter system and laying the roofing pie, since less of them are required than when building a steeper roof.

Metal tile roof with a minimum slope angle - practical and economical option arrangement for southern regions with low average annual precipitation.

If the slope for metal tiles is less than that specified by the manufacturer, this will lead to the fact that the roofing covering will not be able to provide reliable protection of the building from moisture. In addition, in regions with heavy snowfalls, there is a risk of such a metal tile roof collapsing.

Choosing the optimal roof slope

The greater the slope angle, the more total area roof surface. A roof with steeper slopes does not retain snow and water on its surface; precipitation effectively rolls down. But with a high roof, the windage increases; in addition, during its construction it is necessary to spend large quantity material for rafter system and roofing.

The higher and steeper the roof, the more expensive its construction will be and the more difficult it will be to install.

It must be taken into account that due to the increased windage of high roofs, metal tile roofs with high angle slope is not recommended for construction in regions with strong winds, since they may not withstand mechanical load.

The slope of a metal tile roof affects its ability to withstand loads. To increase the strength of a roof with a slight slope, you may need more frequent lathing, which will not only strengthen the rafter system, but also increase the reliability of the roofing covering.

Although there are no specific restrictions on the use of metal tiles for gabled roofs, this material is not very suitable for covering such roofs. If the slope angle exceeds 45 degrees, the sheets of metal tiles may slide down under their own weight. To avoid this, when installing sheets, it is necessary to provide additional points for attaching the material to the sheathing.

The roof of the house must be reliable and beautiful, and this is possible with the correct determination of its angle of inclination for a given type of roofing material. How to calculate the roof slope angle is in the article.

Purpose of the under-roof space

Before calculating the angle of the roof, you need to decide how it will be used. attic space. If you plan to make it residential, the angle of inclination will have to be large - so that the room is more spacious and the ceilings are higher. The second way out is to make a broken line. Most often, such a roof is made of a gable roof, but it can also have four slopes. It’s just that in the second option the rafter system turns out to be very complicated and you simply cannot do without an experienced designer, and the majority prefer to do everything on their own, with their own hands.

When increasing the roof pitch there are a few things to remember:

This does not mean that low-slope roofs are better. They are cheaper in materials - smaller area roofs, but have their own nuances:

• They require snow retention measures to prevent avalanches.
• Instead of snow retainers, roof heating can be used to gradually melt snow and drain water in a timely manner.
• With a small slope, there is a high probability that moisture will flow into the joints. This entails enhanced waterproofing measures.

So roofs with a low slope are also not a gift. Conclusion: the angle of inclination of the roof must be calculated in such a way as to find a compromise between the aesthetic component (the house should look harmonious), practical (with a living space under the roof) and material (costs must be optimized).

Angle of inclination depending on roofing material

The roof on a house can have almost any shape - it can have low slopes, it can have almost vertical slopes. It is important to correctly calculate its parameters - the cross-section of the rafter legs and the pitch of their installation. If you want to lay a certain type of roofing material on the roof, you need to take into account such an indicator as the maximum and minimum angle of inclination for this material.

The minimum angles are specified in GOST (see table above), but often manufacturers give their recommendations, so it is advisable to decide on a specific brand at the design stage.

More often, the angle of the roof slope is often determined based on how their neighbors are made. From a practical point of view, this is correct - the conditions of nearby houses are similar, and if the neighboring roofs are in good condition and do not leak, you can take their parameters as a basis. If there are no roofs in the neighborhood with the roofing material that you plan to use, you can start calculations with average values. They are shown in the following table.

As you can see, in the “how they do it” column, in most cases there is a significant range. So it is possible to vary the appearance of a building even with the same roof. After all, in addition to its practical role, the roof is also a decoration. And when choosing the angle of its inclination, the aesthetic component plays an important role. This is easier to do in programs that make it possible to display an object in a three-dimensional image. If you use this technique, then calculate the angle of the roof in this case - select it from a certain range.

Influence of climatic factors

The angle of the roof is affected by the amount of snow that falls during the winter in a particular region. Wind loads are also taken into account during the design.

Everything is more or less simple. According to long-term observations, the entire territory of the Russian Federation is divided into zones with the same snow and wind load. These zones are mapped and shaded different colors, so it's easy to navigate. Using the map, determine the location of the house, find the zone, and use it to determine the wind and snow load.

Calculation of snow loads

There are two numbers on the snow load map. The first is used when calculating the strength of a structure (our case), the second is used when determining the permissible deflection of beams. Once again: when calculating the angle of inclination of the roof, we use the first number.

The main task of calculating snow loads is to take into account the planned roof slope. The steeper the slope, the less snow can be retained on it; accordingly, a smaller cross-section of rafters or a larger pitch for their installation will be required. To take this parameter into account, correction factors are introduced:

• tilt angle less than 25° - coefficient 1;
• from 25° to 60° - 0.7;
• on roofs with a slope of more than 60°, snow loads are not taken into account - snow is not retained on them in sufficient quantities.

As we can see from the list of coefficients, the value changes only on roofs with a slope angle of 25° - 60°. For others, this action makes no sense. So, to determine the actual snow load on the planned roof, we take the value found on the map and multiply it by a coefficient.

For example, we calculate the snow load for a house in Nizhny Novgorod, the roof slope angle is 45°. According to the map, this is zone 4, with an average snow load of 240 kg/m2. A roof with such a slope requires adjustment - we multiply the found value by 0.7. We get 240 kg/m2 * 0.7 = 167 kg/m2. This is only part of calculating the roof angle.

Calculation of wind loads

The effect of snow is easy to calculate - the more snow in the region, the greater the possible loads. Predicting wind behavior is much more difficult. You can only rely on the prevailing winds, the location of the house and its height. These data are taken into account using coefficients when calculating the roof slope angle.

The position of the house relative to the wind rose has great importance. If the house is located between taller buildings, wind loads will be less than if it is located on open area. All houses are divided into three groups according to the type of location:

• Zone "A". Houses located in open areas - in the steppe, desert, tundra, on the banks of rivers, lakes, seas, etc.
• Zone "B". The houses are located in wooded areas, in small towns and villages, with a wind barrier no more than 10 m high.
• Zone "B". Buildings located in densely built areas with a height of at least 25 m.

A house is considered to belong to a given zone if the specified environment is at a distance of at least 30 times the height of the house. For example, the height of the house is 3.3 meters. If at a distance of 99 meters (3.3 m * 30 = 99 m) there are only small one-story houses or trees, it is considered to belong to zone “B” (even if it is geographically located in a large city).

Depending on the zone, coefficients are introduced that take into account the height of the building (shown in the table). Then they are used when calculating the wind load on the roof of a house.

For example, let's calculate the wind load for Nizhny Novgorod, cottage located in the private sector - belongs to group “B”. Using the map, we find the wind load zone - 1, the wind load for it is 32 kg/m 2. In the table we find the coefficient (for buildings below 5 meters), it is equal to 0.5. Multiply: 32 kg/m2 * 0.5 = 16 kg/m2.

But that is not all. We must also take into account the aerodynamic components of the wind (under certain conditions it tends to blow off the roof). Depending on the direction of the wind and its impact on the roof, it is divided into zones. Each of them has different loads. In principle, rafters can be installed in each zone different sizes, but they don’t do that - it’s unjustified. To simplify the calculations, it is recommended to take indicators from the most loaded zones G and H (see tables).

The found coefficients are applied to the wind load calculated above. If there are two coefficients - with a negative and a positive component, both values ​​are calculated, and then they are summed.

The found values ​​of wind and snow loads are the basis for calculating the cross-section of the rafter legs and the pitch of their installation, but not only. The total load (weight of the roof structure + snow + wind) should not exceed 300 kg/m2. If, after all the calculations, the amount you get is more, you need to either choose lighter roofing materials or reduce the angle of the roof.

Metal roofs are a practical and popular solution for the construction of private low-rise houses. This roofing material is characterized by high bearing capacity, resistance to mechanical damage external environmental factors and intense loads. Durability and reliability finishing coating depend not only on quality, these characteristics are influenced by the roof design, including the correctly selected minimum slope. In this article we will tell you how to choose the right slope angle and check it for compliance with SNiP.

The roof slope is an important design parameter, which indicates the angle formed by the floor plane and the roof slope.

1. This indicator is expressed as a percentage or degrees. It is calculated as the result of dividing the height of the ridge by half the width of the building. The angle of inclination of the slope depends on the technical and operational properties of the material and is regulated by SNiP and the manufacturer’s instructions. It depends on:
2. Possibility of using one or another type of roofing covering.
3. Design, composition and cross-section of rafter frame elements.
4. The ability of a roof to effectively drain precipitation.
5. Cost of roofing work.

Weight of the roofing pie.

Note! If the slope of a metal tile roof is increased from 22 degrees to 45 degrees, the area of ​​the slope will increase by 20%, which will affect the cost of materials (finish coating, waterproofing, insulation, wood), as well as the weight of the structure. It is necessary to decide on the optimal angle of inclination during the preparation of the project in order to correctly determine the load on the foundation.

Optimal values Metal roofs are relatively new constructive solution

• , therefore, the technology of its installation and operation is not clearly regulated by SNiP. Information on what the minimum roof slope should be is provided by the manufacturer, since this indicator directly depends on the technical characteristics of the material itself.
• This indicator is calculated in accordance with the thickness, load-bearing capacity and method of laying the roofing.
• According to SNiP, the minimum angle of inclination of a metal tile roof, if the length of the slope is 6 meters, must be at least 14 degrees. The permissible slope for a metal roof is in the range of 14-45 degrees.

Optimal angle

the slope, which ensures effective removal of precipitation with less space for the slopes, should be 22 degrees.

Important! The minimum slope of a metal tile roof allowed by manufacturers is 11 degrees. Some brands of material can be laid even if the slope is 10 degrees steep. A reduction in this indicator was achieved by the use of new, smoother polymers and more durable steel for the production of roofing.

Please note that the choice of slope slope depends on the roof design. The optimal angle of inclination of the slopes of a pitched roof made of metal tiles is 20-30 degrees, and that of a gable roof is 20-45 degrees.

Features of roofs with a small slope

The minimum recommended pitch for a metal roof is 14 degrees, however experienced craftsmen can efficiently lay this type of roofing material, even if the slope of the slopes is within 10-14 degrees. To increase the reliability of such a design and reduce the risk of leaks, the following measures must be taken:

1. Increase the frequency of the sheathing slats and reduce the pitch between the rafters. To minimize the risk of roof collapse due to intense snow load, it is necessary to strengthen rafter frame structures and install frequent or continuous lathing.
2. Increase overlaps. Manufacturers recommend when installing metal tiles to make a horizontal overlap of 8 cm, and a vertical overlap of 10-15. To eliminate the possibility of leakage in structures with gentle slopes, you can increase the overlap at the joints of the sheets.
3. Insulate joints. To prevent the penetration of melt and rain water between the joints of the sheets, you can treat the seams silicone sealant, although this measure has limited period actions.

Experienced craftsmen claim that the easiest way to make a roof made of metal profiles reliable is to follow the manufacturers’ recommendations and strictly adhere to the recommended angle of inclination.

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