Flat roof slope. How to calculate the slope of a flat roof

Choosing the type of roof, determining the angle of inclination and other roof parameters is an important and crucial task, requiring knowledge of the standards and consideration of the climatic features in the region. The article describes the flat roof, its advantages and features. Explains in detail what is needed and how the slope of a flat roof is made. The information will be useful to all landowners planning to build a dwelling house, ancillary or farm buildings.

Flat roof structure

Flat roof is a single web, not divided into separate sections having a certain slope to organize the flow of water. There are buildings of complex architecture, consisting of several offices with different levels of height. Each part usually has its own roof, but the general rules for each individual section are preserved.

Flat roofs are traditional for the architecture of southern countries, but in the northern regions they are used mainly for non-residential buildings - economic or auxiliary. The reason for this attitude is the abundance of precipitation, which in such quantities does not occur in regions close to the equator.

The traditional device of flat roofs consists of a supporting system ( ), forming an inclined plane with the selected parameters. On top of the truss system, a flooring is created, on which the roofing sheet is fastened. This design is simple, being built quickly enough and allows for the removal of moisture from the roofing space.

The disadvantage is the use of wood, which has a tendency to warping, rotting and fire danger. In addition, wooden rafters have a limited bearing capacity that requires careful calculation for compliance with snow loads. Considerable danger is the impact of the wind, strong gusts of which are able to break the roof, causing significant damage.

are used instead of wooden parts. To increase strength and increase the bearing capacity of flat roofs, a construction method in which the construction of the truss system is abandoned, replacing it with a dense bulk layer - a spreader. it is laid at a certain angle to the horizon, forming an inclined plane on which the roof covering is laid. As a result, the overlap of the upper floor becomes the supporting system, and the leveling of the flat roof reinforces it and forms the required angle of inclination that is optimal for these conditions and materials.

Advantages of flat roofs

The main advantage of a flat roof is the simplicity and efficiency of construction. Such a surface is convenient and safe, allows for maintenance or repair work in optimal conditions. The surface area of ​​such a roof is much smaller than that of cattle structures, which allows significant savings on roofing materials.

An additional advantage of flat roofs is the convenience and ease of installation on them of various technical devices and equipment - satellite antennas, solar panels, etc. simplified repair and maintenance of equipment that can be produced at any time of the year.

There are flat roofs, the surface of which is equipped for lawns, swimming pools, recreation corners and other areas. In these cases, the use of the surface is most effective, although it requires significant costs for the design and maintenance of sites.

Slope for a flat roof: whim or technical need

Slope is a necessity causes an abundance of precipitation. Rain or melt water must be able to be removed from the surface, otherwise the roof covering will quickly collapse and fail. In the summer, stagnation of rainwater provokes aggressive exposure to chemical elements and oxygen dissolved in the mass of precipitation. In winter, the presence of moisture is even more dangerous - as the temperature drops, it will freeze and expand. The smallest surface cracks, where moisture penetrates, will increase.

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For the organization of operational water flow, at least a minimum flat roof slope is required, allowing water to be removed by gravity from the roof. The best solution to the problem for large roofs is a leveling of a flat roof with bulk materials, forming a plane with the desired angle and in parallel performing the functions of insulation and sound insulation.

Minimum and maximum slope of flat roofs according to SNiP

Roof tilt angle is a value regulated by technical standards. In SNiP there is a joint venture 17. 13330. 2011, or, more simply, in the Code of roofing. It defines the standard values ​​of the angle of inclination of the roof covering, depending on the roof construction, as well as the materials used. The values ​​that a razuklonka flat roof, SNiP determines in accordance with the surface properties of various roofing coatings. The degree of roughness of the metal fabric is much less than that of soft or wavy surfaces.

The slope is measured by in various units of :

• In percent .

• The ratio of height to length .

• In degrees .

Such an abundance of units caused the specifics of construction work - it is much more difficult to control the angle with a protractor at the site than to measure linear dimensions.

The situation is somewhat more complicated when building a roof with a large area. To make a bias in such conditions is not always rational. The solution to the problem is the slope of a flat roof with an internal drain, when the entire canvas is divided into relatively small areas with drain funnels. Water falling into them is discharged through the piping system to storm sewers. Such a roof construction is more complicated and requires the creation of a drainage communications system, but on large buildings this option is optimal.

In practice, slopes are much smaller and largely dependent on local climatic conditions. The main factors influencing the choice are:

• Amount of snow in winter.

• The force of the winds prevailing in the region.

The weight of snow is a significant load. It can be determined by the tables in the SNiP appendices, which show the average annual values ​​for different regions of the country. The lower the angle, the less the possibility of independent descent of snow masses. At the same time, a large angle of inclination increases wind loads, which are dangerous in that the roof covering can be torn off the supporting surface. Destruction occurring at the same time, can lead to loss of life and threaten not only this building, but also all objects located nearby.

The choice of angle is based on the magnitude of the expected loads and is adopted in accordance with them. If the roof structure consists of durable materials that can withstand a static load of snow weight, then usually try to minimize wind effects that have a dynamic nature and unpredictable direction.

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How to calculate the slope of a flat roof

Specialized calculation of the angle of inclination is an extremely difficult engineering task. The requirements of SNiP in this matter are of advisory value and determine only the permissible limits for each type of roofing. For an unprepared person, performing such a calculation is unavailable and even dangerous. It is necessary that the design was carried out competent and experienced professionals.

As an option, you can use an online calculator, which are abundantly available on the Internet. It is recommended to duplicate the obtained value on another resource in order to compare the data and balance the results. It should be borne in mind that online calculations are only of advisory value and should not be used in the construction of critical structures.

Roofing materials for flat roofs depending on the angle of its slope

Choice of roofing material must first be determined by the angle of the roof. There is a mass of variants :

• Roofs made of piece materials and corrugated sheets

• Metal roof .

• Soft roof .

You can create a tilt angle by creating a supporting structure of the desired configuration or by filling the surface with an inclined layer of insulation.There are also specialized types of materials, for example - a wedge-shaped insulation from the company TechnoNIKOL, the leveling of the roof with which is created by laying the plates of a specific shape.

The selection of the most suitable material is made by comparing local climatic conditions, construction parameters, capabilities and preferences of the owner. All these factors are equally important, but it is recommended to give priority to decision-making to representatives of a construction company with experience and special knowledge.

In the video you can see the device of flat roofs:

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Conclusion

In conclusion, an increase in the number of buildings with a flat roof should be noted. The fashion for such architectural solutions that came from Europe requires the use of appropriate technologies and materials. Approaching the construction with the usual standards, common in Russia, is irrational and impractical. Buildings with flat roofs require the creation of a special project that takes into account climatic features, material properties, hydrogeological conditions.