The angle of inclination of the pitched roof is snip. Flat roof slope according to snip. Why is there a slope on a flat roof?

Choosing the type of roof, determining the angle of inclination and other parameters of the roof is an important and responsible task that requires knowledge of standards and taking into account climatic features in the region. The article provides a description of a flat roof, its advantages and features. It explains in detail why a flat roof is needed and how it is sloped. The information will be useful to all owners of plots planning to build a residential building, auxiliary or outbuildings.

Flat roof structure

A flat roof is a single sheet, not divided into separate sections, and has a certain slope to organize water flow. There are buildings of complex architecture, consisting of several departments with different levels of height. Each part usually has its own roof, but the general rules for each individual area remain the same.

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

The traditional design of flat roofs consists of a support system (rafters) forming an inclined plane with selected parameters. A deck of boards is created on top of the rafter system, on which the roofing sheet is attached. This design is simple, erected quickly enough and allows for the removal of moisture from the under-roof space.

The disadvantage is the use of wood, which is prone to warping, rotting and poses a fire hazard. In addition, wooden rafters have limited load-bearing capacity, requiring careful calculation to comply with snow loads. A significant danger is posed by the influence of wind, strong gusts of which can rip off the roof, causing significant destruction.

In order to increase the strength and load-bearing capacity of flat roofs, a construction method has been developed in which the construction of the rafter system is abandoned, replacing it with a dense bulk layer - a slope. it is laid at a certain angle to the horizon, forming an inclined plane on which the roofing covering is laid. As a result, the roof of the upper floor becomes the supporting system, and the slope of the flat roof strengthens it and forms the required angle of inclination, optimal for the given conditions and materials.

Advantages of flat roofs

The main advantage of a flat roof is its simplicity and cost-effectiveness of construction. Such a surface is convenient and safe, allowing maintenance or repair work to be carried out in optimal conditions. The surface area of ​​such a roof is significantly smaller than that of pitched structures, which allows significant savings on roofing material.

An additional advantage of flat roofs is the convenience and ease of installation of various technical devices and equipment on them - satellite dishes, solar panels, etc. simplifies the repair and maintenance of equipment, which can be carried out at any time of the year.

There are flat roofs, the surface of which is equipped for lawns, swimming pools, recreation areas 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 the sites.

Slope for a flat roof: whim or technical necessity

Slope is a necessity caused by the abundance of rainfall. Rain or melt water must be able to be removed from the surface, otherwise the roofing will quickly deteriorate and fail. In the summer, stagnation of rainwater will provoke the aggressive action of chemical elements and oxygen dissolved in the mass of sediment. In winter, the presence of moisture is even more dangerous - when the temperature drops, it will freeze and begin to expand. The smallest cracks in the surface where moisture penetrates will begin to increase.

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To organize efficient water drainage, at least a minimum slope of the flat roof is required, allowing water to be removed from the roof by gravity. The optimal solution to the problem for roofs of a large area is to slope the flat roof with bulk-type materials, forming a plane with the desired angle and simultaneously performing the functions of insulation and sound insulation.

Minimum and maximum slope of flat roofs according to SNiP

The angle of inclination of the roof is a value regulated by technical standards. SNiP contains SP 17.13330.2011, or, more simply, in the Code of Roofing Rules. It determines the standard values ​​of the angle of inclination of the roofing covering depending on the roof structure, as well as the materials used. SNiP determines the values ​​​​that the slope of a flat roof has in accordance with the surface properties of various roofing coverings. The degree of roughness of the metal sheet is much less than that of soft or wavy surfaces.

The slope is measured in different units:

In percentages.

Height to length ratio.

In degrees.

This abundance of units of measurement is caused by the specifics of construction work - checking the angle using a protractor on the site is much more difficult than measuring linear dimensions.

The situation is somewhat more complicated when constructing a roof with a large area. It is not always rational to make a slope in such conditions. The solution to the problem is the slope of a flat roof with an internal drain, when the entire roof is divided into relatively small sections with drainage funnels. Water entering them is discharged through a pipeline system into the storm sewer. This roof design is more complex and requires the creation of a system of drainage communications, but for large buildings this option is optimal.

In practice, the angles of inclination are much smaller and largely depend on local climatic conditions. Main factors influencing the choice are:

Snow amount in winter.

The power of the winds prevailing in this region.

The weight of snow is a significant load. It can be determined from the tables in the appendices of SNiP, which indicate the average annual values ​​for different regions of the country. The lower the angle, the less possibility of independent snow melting. At the same time, a large angle of inclination increases wind loads, which are dangerous because the roofing covering can be torn off the supporting surface. The destruction that occurs in this case can lead to casualties 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 from the weight of snow, then they usually try to minimize wind influences, which are dynamic in nature and unpredictable in direction.

How to calculate the slope of a flat roof

Specialized calculation of the angle of inclination is an extremely complex engineering task. The requirements of SNiP in this matter have a recommendatory value and determine only the permissible limits for each type of roofing. For an unprepared person, performing such a calculation is inaccessible and even dangerous. It is necessary that the design be carried out by competent and experienced specialists.

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

Roofing materials for a flat roof depending on its slope angle

The choice of roofing material should primarily be determined by the angle of the roof. There are a lot options:

Roofs made from piece materials and corrugated sheets

Metal roofing.

Soft roof.

You can create an angle of inclination 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, wedge-shaped insulation from the Technonikol company, the slope of the roof with which is created by laying slabs 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 in decision-making to representatives of the construction company with experience and special knowledge.

Video description

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

Conclusion

In conclusion, it should be noted that the number of buildings with flat roofs has increased. The fashion for such architectural solutions, which came from Europe, requires the use of appropriate technologies and materials. Approaching construction using the usual standards common in Russia is irrational and impractical. For buildings with flat roofs, the creation of a special project is required, taking into account the climate, material properties, and hydrogeological conditions.

It is necessary to decide on the roof structure at the design stage of the building. If you choose a flat option, then it is very important to imagine all the positive and negative aspects of operating a building with such a roof. The choice of roof type also determines the use of special materials and technological techniques during construction.

Flat roof installation

The flat type of roof did not always evoke positive emotions among builders. This was due to some prejudices in the construction and operation of a flat roof - lack of aesthetics, inefficiency, fragility.

Recently, there has been a tendency to revive the popularity of flat roof structures; new construction technologies and innovative materials have played a significant role in this.

A flat roof made of modern materials reliably protects the house and looks beautiful

A flat roof structure can be imagined as a multi-tiered “pie” with several layers:

1. A reliable foundation. Most often, this role is played by a reinforced concrete slab or a metal profile structure.
2. Vapor barrier coating. The most popular are bitumen or roll materials.
3. Thermal insulation layer. Mineral wool, expanded clay, polystyrene foam, cement screed - the main components used by builders for thermal insulation.
4. Waterproofing. There are a lot of materials for protecting roofs from moisture (bitumen-based mastics, PVC membranes, liquid fusion compounds, etc.), the choice depends on the material and production capabilities of the developer.

The listed order of layers is not mandatory; it can be different in different flat roof designs.

All roofing elements must be of high quality; a flaw in at least one of them can lead to problems in the normal operation of the roof.

Pros and cons of a flat roof

A flat roof, despite its apparent simplicity, has a number of useful characteristics that attract builders. Such designs also have disadvantages that must be taken into account.

Advantages of flat roofs

Photo gallery: options for using a flat roof

Modern technologies allow you to plant grass on the roof and arrange a children's playground exactly like on the ground. You can get to such a cafe by elevator. Only a flat roof can be decorated so beautifully and modernly. On the roof you can place a table, benches, a hammock and enjoy your relaxation. Swim in the pool , practically without leaving home - you can only dream about this

Disadvantages of a flat roof structure

No roof can be perfect. There are significant disadvantages to a flat roof:

• instability to snowfalls (heavy snowfall increases the likelihood of a roof failure; leaks are possible during heavy spring melting);
• the need to construct additional water drains;
• increased requirements for the condition of hydro- and thermal insulation of the roof.

If internal drains are made on the surface of flat structures, then they require constant monitoring of their condition (it is necessary to remove debris, eliminate freezing, etc.).

Types of flat roofs

There are two main types of flat roofs:

The structural differences between the two types of flat roofing lie in the order in which the layers are laid. In an unused roof, the top layer is waterproofing, which quickly deteriorates when exposed to various natural factors - sun, wind, precipitation, etc. This option is not suitable for active use of the roof.

The inversion roof is “packed” differently. The sequence of layers here is as follows: concrete, waterproofing, thermal insulation, protective coating. The last layer is often made of drainage or geotextile. Such durable structures are in demand among designers who want to make maximum use of the entire roof space.

Holding concerts, building car parks, summer cafes and studios implies a high degree of load, so builders lay additional reinforced materials between the insulating layers.

Flat roof slope

A flat roof should not be absolutely flat; a minimum slope must be provided. Otherwise, it will be difficult to drain wastewater; moisture from precipitation will accumulate on the roof and contribute to its rapid destruction.

In the absence of a slope, stagnant zones with negative aspects may appear:

• accumulation of moisture;
• germination of seeds blown by the wind;
• formation of lichens.

To prevent this from happening, you should make a slope of one to four degrees on a flat roof. With such a difference in levels, melt and waste water will not linger on the surface, which will extend the service life of the roofing.

Work to create a slope on a flat roof is called slope.

You can achieve the desired slope on a flat surface by using different materials:

1. Backfill components (expanded clay, perlite, etc.).
2. Different layers of insulation.
3. Lightweight concrete mixtures on various bases (polymers, bulk materials, etc.).

Each of these solutions in relation to deviation has its own characteristics. The use of backfill materials during long-term operation of the roof does not provide a clear angle of inclination. Bulk materials can slide off the roof and shift, which leads to a change in slope. It is difficult to achieve a smooth height difference if you use large expanded clay (more than 20 mm).

Lightweight concrete masses do not have such disadvantages, but they are quite heavy; not every roof structure provides for such additional weight. These materials cannot be used in cases where the building has already been built and its design is not designed for a large load on the frame and foundation.

Modern industry produces materials that help create the necessary and smooth slope on a flat roof. The polymer base of these mixtures makes them plastic, which is a big plus when constructing flat roofs.

There are other possibilities for creating a slope on a flat roof:

• installation of metal profile structures covered with flat slate;
• construction of sheathing (rarely used due to the cost and impossibility of creating small slopes);
• installation of wedge-shaped thermal insulation boards.

The last of these methods is gaining popularity among builders, because this tilting method has its advantages:

• easy installation. Thermal insulation boards are already cut at a certain angle. Their installation does not require any special skills; it is enough to simply lay the wedge-shaped slabs on a flat surface of a flat roof to obtain the required slope.
• light weight. During construction work you will not have to resort to the help of any lifts. In addition, the insignificant total mass of the insulation boards will not in any way affect the performance characteristics of the roof in the future.
• Independence from external conditions. Laying wedge-shaped thermal insulation can be done in any weather.

Video: tilting a flat roof

Insulation and drainage for flat roofing

To avoid rapid failure of a flat roof, you should take care of its proper insulation and drainage.

Drainage

The drain on a flat roof is installed outside or inside the building. The choice of water drainage method depends on climatic conditions:

Video: installation of an inlet funnel on a flat roof

Insulation

Thermal insulation of a flat roof is carried out differently from the insulation of pitched surfaces.

This process includes two important points - vapor barrier and thermal insulation. Depending on the type of roof (classical or inversion), the order of the layers changes.

The following are used as thermal insulation:

• mineral wool;
• Styrofoam;
• polyurethane foam;
• ecological cotton wool;
• foam concrete.

A good vapor barrier can be provided by a polypropylene film and a built-up mass with a bitumen base.

Photo gallery: flat roof insulation

A flat roof can be insulated in a well-known way - by filling with expanded clay. It is easier and faster to insulate large surfaces with mineral wool. To insulate flat roofs, modern materials are increasingly being used, for example, extruded polystyrene foam. Foam glass provides not only thermal insulation, but also an excellent soundproofing effect. Foam concrete is poured automatically using a pump and flexible hose, so you can handle this work alone

Flat roof ventilation

To begin with, let’s outline the negative aspects that will arise on a flat roof without ventilation. A flat roof without ventilation will be “loaded” with condensate. Natural physical processes will lead to the fact that warm air, rising upward, will settle not on the elements of the attic (as on a pitched roof), but on the reinforced concrete base. The result of such unfavorable processes will be the appearance of fungus and mold on the ceiling.

In the future, steam and heat insulation and other roofing elements will suffer. To prevent this from happening, it is necessary to install deflectors and aerators on the roof. Their installation is provided for at the building design stage.

The inflow and outflow of air is carried out due to different pressures outside and inside the building. A flat roof will “breathe” if artificial ventilation devices are placed on it. This will help preserve the layers of hydro- and thermal insulation from destruction, and prevent the spread of air bubbles and swelling of the roofing material.

Materials for covering flat roofs

The following roofing materials are used for flat roofs:

• mastics;
• polymer membranes;
• bitumen-based roll materials.

They provide good waterproofing and excellent resistance to mechanical stress and temperature changes.

Bituminous materials

The basis of many roll coatings is oxidized or modified bitumen. Roofing felt, stekloizol, rubemast, euroroofing felt are the main types of bituminous materials used on flat roofs.

Table: characteristics of rolled bitumen materials

Polymer membranes

These materials have become popular relatively recently. The advantage of such flat roof coverings is plasticity, resistance to damage, resistance to temperature changes, and easy installation. Another big advantage of polymer coatings is their production footage. The length of one roll of polymer membrane is from 20 to 60 meters, so it can very quickly cover large areas of flat roofing.

The service life of roofs with polymer membranes is 30–50 years.

Mastics

The positive aspects of using mastic materials are the absence of seams and the integrity of the coating. The service life of such roofs is from three to ten years.

Applying viscous and viscous mastic to the roof surface is a simple process; this layer becomes hard at normal air temperatures. Mastics are also used as an adhesive base for the installation of roll materials.

There are cold and hot mastics. The first type does not require additional manipulations during preparation and installation; in the second case, the mixture will need to be heated to 180°. It is safer to work with cold mastics, but hot materials set faster.

Flat roof repair

Any roof needs constant inspection, maintenance and repair. On the roof, under the influence of various factors, cuts, damage, breaks, swelling, peeling and other problems may occur that interfere with the normal use of the roof. To eliminate such negative conditions, repair work must be carried out. They can be current, emergency or capital in nature.

Emergency repair is a forced, unplanned measure, carrying out emergency measures to restore the integrity of the roof. Current and major repairs of flat roofs are planned in advance. The scope of work carried out during current and major repairs differs significantly. Major repairs require more time and costs, and the area of ​​repaired coatings is also much larger.

During emergency and scheduled repairs of a flat roof, patches are most often installed on the damaged area. Materials for repairs are selected individually in each case. One of the latest “helpers” when updating a flat roof is self-adhesive tape with an applied bitumen coating. It is very convenient and effective to use it for roof repairs. There is only one limitation: this tape is not suitable for repairing damage over a large area.

Repairs on a flat roof are much easier and safer than on a pitched roof. Repair times on such a surface are also much shorter.

Video: flat roof repair technology

Economic nuances of using a flat roof

If you are wondering about the economic benefits, then you should consider some points when constructing a flat roof.

Of course, the construction of a flat type of roof is less expensive, since there are no costs for constructing a rafter system. This will be the case with operation if repairs to the rafter part of the pitched roof are required. In a flat roof, such an expense item is simply absent.

A pitched roof will require more investment also because it is clearly visible, being an integral part of the facade of the building. The materials that are used in the construction of the top layers in a flat roof are not always appropriate for a pitched roof. They can be simpler and more uncomplicated, while on a pitched roof it is better to use not only reliable, but also beautiful finishes.

The costs of construction, maintenance and repair of a flat roof largely depend on its intended purpose. The cost will be much lower if the roof is not in use.

The construction, maintenance and operation of a flat roof have their own natural characteristics. There are advantages and disadvantages to using a flat roof. Considering the purpose of using the building, the flat roof should be installed with strictly defined materials.

A flat roof, which is built in accordance with the requirements of building codes, always has a slight slope. If it is minimal, an inexperienced observer will not notice. But if there is no slope at all, it will be immediately visible. The fact is that in the absence of at least some inclination of the structure, rain or melt water will inevitably collect on it.

Even if the surface of a flat roof is created perfectly flat, and, it would seem, there can be no talk of any puddles, the reality is different. Under the influence of wind, solar radiation, rain of varying acidity, and temperature changes, the roof becomes deformed over time, creating zones in which water or dirt brought by the wind can be retained. If there is a minimal slope, the chances that water or snow will linger on the roof for a long time are much less.

What's the point of slanting?

It would seem that sooner or later the snow lingering on the roof will melt, and the water will either dry up or the drainage system will cope with it. The experience that eventually resulted in the recommendations of the Building Code suggests the opposite. Water has the ability to destroy the roof structure in a variety of ways.

Firstly, water on the roof is not completely distilled; its chemical analysis will show the presence of dissolved oxygen and a whole range of substances that will actively destroy the roof material. Secondly, during the cold season, water can change its state of aggregation several times a day. Among other things, this is also a change in volume, which carries a powerful destructive force.

The slope of a flat roof is also necessary to prevent dust from accumulating on it. Many have seen vegetation on the roofs of residential and industrial buildings. It would seem, where do the grass and trees come from there? But the wind, water and sun do their job steadily. And plant roots, as is known, are capable of destroying even very strong materials.

How is slope measured and determined?

The parameters of a flat roof, the list of which includes the minimum slope, are regulated by the set of rules SP 17.13330.2011 SNiP II-26-76. A document so complex in notation is easier to distinguish by its name. It's called the Code of Rules for Roofing, or Theroofs in English.

The scope of the document is the design of roofs using rolled, bitumen and other roofing materials, several types of tiles, slate and tiles, galvanized steel and copper sheets, profiled sheets, aluminum, zinc-titanium and other structures.

Before considering the table available in the set of rules, it should be clarified that the slope of a flat roof can be measured either in degrees or as a percentage. There are also relative units of the 10/12 type, but they are rarely used.

Table regulating slope

In paragraph 4.3. The set of rules mentioned above contains a table that sets out the standards that determine the slope of a flat roof, that is, its minimum size. The values ​​depend on the type of materials used to construct the roof, as well as on some other factors.

So, if the roof is constructed from rolled materials or bitumen-based mastics, it should be inclined in the range from 1° to 6° (1.5-10%), if gravel or other coarse substances are poured on top. If the top layer is foil, the slope of the flat roof varies from 1° to 16° (1.5-25%).

When using polymer roll materials, the slope should not exceed 1° (1.5%) without a protective layer and 2° (3%) with a protective layer.

Completely different values ​​are provided for piece materials, metal sheets and concrete structures. For tiles and slates, the minimum slope of a flat roof is 12° (20%) to 22° (40%). Metal sheets can be placed at a minimum of 7° (12%), reinforced concrete trays - 3°-6° (5-10%).

The standards allow the use of significant slopes, but some additional requirements must be met.

How slopes are created

The process of creating roof slopes is usually called de-sloping. In this process they use:

• bulk materials, in particular perlite and expanded clay;
• lightweight concrete compositions based on the same perlite and expanded clay;
• lightweight concrete compositions based on polymer materials;
• insulation materials.

What material will be used depends on the design of the building, the required slope and some other factors. For example, lightweight concrete in some cases may be too heavy, creating a significant load. On the other hand, when using bulk materials it is impossible to create a large angle. In general, different materials have their own advantages, disadvantages and scope of application.

Since the flat roof used to cover office buildings, industrial facilities and residential buildings does not have slopes, increased demands are placed on the quality of waterproofing. To avoid leaks, three to five layers of material are used, but a flat roof surface is not able to drain water as effectively as a pitched one. Because of this, areas where moisture accumulates are formed; they dry out only during the hottest periods of the year. The rest of the time, non-evaporating puddles negatively impact the waterproofing layer, destroying it.

In addition, in places where moisture accumulates, particles of soil and dust settle, forming a kind of substrate. The wind carries seeds into this favorable environment and they germinate. Destroying the roofing pie. In order to organize the removal of excess moisture and its movement to the drainage system, a flat roof slope is laid. So the name “flat” is just a figure of speech; in fact, its surface is located at a slight angle, invisible to the eye, without the use of a special geodetic instrument. What the slope should be and how it can be created, we will tell you in this article.

Building codes

The minimum slope of a flat roof is regulated by clause 4.3 of SP 17.1333, adopted and approved in 2011. It allows a roof surface inclination angle in the range of 1.5-10% or 1-6 degrees. That is, the smallest slope allowed by regulations, 1.5% or 1 degree, creates conditions for the movement of water to drainpipes and gutters and prevents stagnation. Steeper angles are rarely used, since on a large roof area, rolled waterproofing materials slide down to the base.

The process of creating a slope is called flat roof slope. This task is performed in various ways using:

1. Thermal insulating material;
2. Backfill materials;
3. Lightweight mixtures of concrete with backfill materials;
4. Lightweight mixtures of concrete and polymers.
5. Plastic panels

Important! The slope of the flat roof in use should not exceed 3 degrees, as increasing it reduces the safety of use.

Deflection with thermal insulating materials

The structure of any flat roof implies the presence of a layer of thermal insulating material. To set the angle of the roof surface, adjust the thickness of the insulation. To prevent slipping and maintain a given angle, it is fixed to the base of the roof with self-tapping screws. If the base of the roof is well cleaned, the insulation can be glued to it or special plastic supports can be used to hold the layers of thermal insulation together.

This method of deflection has advantages; it is good because:

• It is relatively cheap. Since insulation is already necessary to form the roofing pie, costs increase only through the purchase of glue or fasteners.
• Quite accurate. Using this method, you can accurately set an angle of 1-4 degrees, which is quite sufficient for effective drainage.
• A light weight. Unlike most other methods, sloping a flat roof using insulation does not require reinforcement of the base, since the thermal insulating agent, most often mineral wool or expanded polystyrene, has a low mass.

Deflection with backfill material

Creating a slope angle for a flat roof using backfill material begins with the installation of waterproofing material. This role is most often played by glass insulation; it is a modern one based on fiberglass, due to which it has increased tensile strength and a service life of more than 20 years. Expanded clay or perlite is poured onto the glass insulation so as to maintain the required slope angle. After this, the backfill material is covered with a polyethylene film arranged in overlapping strips and the remaining layers of the roofing cake are laid according to the design.

However, this method of creating a flat roof slope has disadvantages:

• Large granules (more than 20 mm) do not allow you to accurately maintain the specified angle and make it smooth.
• The backfill material cannot be rigidly fixed, which is why it moves over time. Moreover, this can happen even at the stage of forming the roofing pie, if the expanded clay is not poured with cement laitance. However, in this case, the time spent on drying increases.
• Backfilling is done almost by eye, so it is impossible to maintain the exact angle of inclination.
• Due to the large weight of the backfill material, reinforcement of the concrete roof base is required.

Sloping with concrete mixtures

To set the slope, you can use concrete-based mixtures. This method is not suitable for reconstruction or partial repair; it can only be used for newly created roofs. In order to pitch the roof with concrete mixtures, special equipment and highly qualified workers are required. Two types of concrete mixtures are used:

• With the addition of expanded clay and perlite, slag.
• With the addition of polymer materials.

This method has only two disadvantages: the high cost, which consists of the wages of highly skilled workers and the high cost of polymers, and the second is the large weight of concrete, which increases the load on the base of the roof.

Bend using panels

The most innovative way to set the angle of the roof is to use special plastic panels. They, like pieces of a children's puzzle, are assembled and placed on a pre-prepared base, and then filled with liquid rubber. The different thicknesses of the panels ensure the most accurate observance of the angle of inclination of the surface. But this method also has its own characteristics:

Monitoring the effectiveness of the deviation

To check whether the slope is done properly and whether water is effectively drained from the roof surface, use one of two methods:

The slope, made in accordance with building codes, protects the upper floors from leaks and extends its service life.

Video instruction

In order for the roof to serve for a long time and be safe during the entire period of operation, it is necessary to prepare a high-quality project in advance. Also, don’t forget about materials, which you certainly shouldn’t skimp on, so that you don’t have to overpay, as in one well-known saying. They must not only correspond to the climatic conditions of residence, but also favorably emphasize the architectural features of a private home. After all, no one canceled the design! But, in addition to this, the slope of flat roofs must also be taken into account. This is as important a stage as the selection and calculation of rafters and insulation.

The efficiency of a roof is directly dependent on its slope. And when calculating this parameter, it is necessary to take into account the region of residence, why exactly the attic is being built and the roofing materials used.

The advantage of flat roofs

Despite the fact that during the construction of private houses, flat roofs are made in isolated cases, they have a number of advantages. And above all - low cost of work, since less building material is spent in comparison with construction. Their installation is not as complicated as it might seem. Flat roofing is also easy to maintain and repair.

If necessary, the roof can act as an additional platform. You can arrange a small pool or a children's corner on it. In addition, a slight slope of flat roofs will allow the installation of any equipment, often air conditioners.

The invaluable advantages of a flat roof make it in demand not only abroad, but also in Russia. This is despite the seemingly unattractive design. Currently, the inversion type of roofing is gaining popularity. But that's not what we're talking about. First you need to understand whether you need to make a bias.

The need for a slope on flat roofs

Many buildings are made with a flat roof. However, it is not entirely like that and has a slight bias, since this is spelled out in the requirements of SNiP and dictated by vital necessity. Indeed, in the absence of a slope, rain or melt water will certainly begin to accumulate on the roof over time.

Even if the roof surface is perfectly flat and there should be no talk of any puddles, reality shows the opposite. Various natural factors come into play:

• exposure to wind;
• solar radiation;
• precipitation;
• temperature changes and others.

As a result of all this, over time the roof begins to deform. Accordingly, places are formed in which moisture and dirt, blown by the wind, begin to accumulate. If there is at least some slope on flat roofs, this probability is minimal.

What are the consequences?

It would seem, what terrible thing can happen because of water? Everyone knows that it is the basis of life for all things on earth. However, this element can easily destroy almost anything in a variety of ways.

And since we are talking about water, which usually accumulates on the roof, its chemical composition contains a variety of substances. They have a detrimental effect on And in winter, the liquid generally turns into a solid state - this is where the powerful crushing force is hidden! And if there is at least some minimal slope of the flat roof, the worst can be avoided.

Many have noticed how vegetation is blooming on the roofs - the wind, along with the sun and water, are doing their job. And as you know, the root system of plants is a fairly strong organ that can destroy almost any durable material. Over time, of course, but it doesn’t get any easier.

Slope designation

All parameters of a flat roof, including the slope, are regulated by the document SP 17.13330 SNiP II-26-76, which is called “Code of Roofing Rules. The Roofs” (translated from English as the roofs - roofs). This document applies to the design of roofs made of almost any material:

• bitumen and roll;
• slate;
• from tiles;
• profiled, galvanized, steel, copper sheet;
• aluminum, zinc-titanium and other similar structures.

The amount of inclination of the slope relative to the horizon, called the roof slope, can be designated in different ways. In practice, its value is usually indicated in degrees, which is more convenient.

However, in documentation you can find the slope of a flat roof written as a percentage. However, there are significant differences between these designations. 1 degree equals 1.7%. 31 degrees will already equal 60%. In this regard, it is important to know such ratios so as not to make mistakes when making calculations.

What should you know?

When making a roof slope, it is worth clearly understanding the purpose of this process. Perhaps protection from the harmful effects of external natural factors is necessary. In some cases, the slope of the roof depends on the architectural features of the surrounding buildings, and there is no desire to stand out too much from their background. The material used also matters, since each has its own indicators that are acceptable during installation.

But special attention should be paid to the fact that at the maximum slope of a flat roof, the roof will act as a sail, which is not good. On the other hand, precipitation will not accumulate on such a roof. Neither drops of rain nor snow will stay long on such a surface.

The area of ​​application of the attic also matters. It is better not to make steep slopes when arranging an attic. And in any case, financial capabilities also make their own adjustments. If you need to build a roof at an angle of 45 degrees or more, you cannot avoid increasing costs for roofing materials. Depending on this, the slope angle is selected.

Dependence of roofing material on the degree of slope

In addition to the fact that the slope of a flat roof is directly dependent on the type of material used, this parameter also affects the amount of thermal insulation agents. If, for example, the slope angle is small, then more thermal insulation will be required, since moisture is in no hurry to leave the sloping roof.

Different materials are used to construct the roof. This includes slate (asbestos-cement, cellulose-bitumen sheets), metal tiles, roofing felt and other options. Let's look at the most common ones.

Metal tiles

This material has considerable weight when compared with other analogues. Therefore, it is important to correctly calculate the roof slope. This is especially critical for areas with frequent and strong winds and hurricanes. In this case, the slope angle should be as low as possible.

If you select a flat roof slope that is too high, it will swell, which will increase the load on the supporting structure. As a result, the roof may collapse prematurely.

As a rule, for such a roof the optimal slope angle will be 27 degrees. Then the roof will reliably protect the house from moisture. The minimum value is 14 degrees. When using soft material, the slope angle can be reduced to 11 degrees. Only the roof in this case requires additional sheathing.

Corrugated sheet

This material is considered the most popular for roof construction. It is lightweight yet durable enough to meet many property owner requirements. Carrying out installation is not particularly difficult, and you can do it on your own with the support of your loved ones.

As for the requirements for the slope of a flat roof, SP 17.13330.2011 (set of rules) allows the construction of a roof with an angle of at least 8 degrees and with a sheathing pitch of 40 cm (grade H-60, H-75). However, material grades S-8, S-10, S-20 and S-21 allow a slope angle of no more than 15 degrees. The pitch of the sheathing is from 5.0 to 6.5 cm, but sometimes a solid structure is used.

However, 8° is the minimum value that is suitable for roofs of commercial or industrial buildings. For residential buildings, the minimum threshold is 10°. But as for the maximum slope, there are no special restrictions. For this material, you can build roofs with a slope of 70°, or a large angle.

The optimal value for the slope of a flat roof (the norms will be observed) will be 20°, which will allow snow and water to drain off in a timely manner. Then you won’t need a very large investment, and the roof can be laid in two layers. Due to this, the risk of moisture seeping through fasteners will be minimized.

Soft roof

Here, too, there are different values ​​of the angle of inclination, if we take into account (like roofing felt, ondulin) or modern polymer (membrane) products. As a rule, the inclination angle is in the range of 2-15°. More accurate indicators depend on the number of layers being laid.

If it is necessary to lay a two-layer roof, the angle is 13-15°. The inclination of the three-layer coating will be smaller - in the range from 3 to 5°. When using modern membrane material, the threshold is even lower - only 2-5°.

In other words, the property owner himself chooses the slope of the flat roof; and rules) are not violated. However, one should take into account the fact that the roof must withstand loads that are not only temporary, but also permanent. The first includes precipitation depending on the season and its weight, gusts of wind. The second is the mass of the roofing material itself, which acts on the supporting structure.