Construction of a flat roof. Projects of houses with a flat roof

Flat roof in a private home provides many different possibilities. With such a simple design, you can save on roofing materials and labor, and installation is carried out in less than short term. It is also easier to place on its surface various systems: antennas, hoods, solar panels and others. In addition to all this, additional space can be used by arranging a garden, recreation area or greenhouse on it.

However, despite the cheaper installation, many nuances must be taken into account so that such a roof does not become a “headache” for the home owner.

Flat roof design

A flat roof, like any other, must fully perform all its functions: protection from water and its drainage and thermal insulation. In addition, it must have sufficient strength to withstand external loads.

This is what determines the structure roofing pie, consisting of the following required elements.

Base. This part bears all the main loads. The ceiling must be very durable, but it all depends on whether the roof will be used or not. Most often, the base is a reinforced concrete slab laid on load-bearing walls, less often on non-residential buildings - a layer of profiled sheets.
Vapor barrier layer. Performs protective function, which consists in preserving materials from steam penetrating from inside the room.
Thermal insulation. Reduces heat consumption from the house.
Waterproofing. A flat roof does not drain away all the water completely, like gable roofs; as a result, high-quality protection is needed from the penetration of room moisture.

For normal moisture removal, a slope is used. Most often, this is a screed that forms angles of inclination along which water can flow into a prepared system of trays for its removal from the roof plane.

Saving on any parts of a flat roof is unacceptable, otherwise it will lead to leaks, freezing and other negative phenomena of a poorly installed roof pie.

Types of Flat Roofs

The presence, order and sequence of individual elements of the roofing pie determine the type of roof. Such designs are distinguished flat floors:

Unexploited. These structures can be seen on multi-story buildings. It is believed that their surface is not intended for use and is designed for short-term stay of people. In this option, on non-residential buildings you can use a profiled sheet as a base.
Exploited. In this case, it is necessary to have a concrete base capable of withstanding heavy loads. The surfaces can be used as a garden, recreation area or even car parking. In addition to a solid base, it is important to observe the angle of inclination, which should not exceed 3 degrees.

Inversion. The design involves changing the order of layers of the cake. The waterproofing is placed under the insulation, which allows it to be protected from damage. Quite often this type of roofing is used in the construction of private residential buildings.
Ventilated. These types of roofing have a ventilation system (built-in aerators) that evaporate excess moisture from the thickness of the roofing cake. Can be combined with other types of roofs.

In addition, the type of roof depends on other factors, for example, whether the room is heated or not.

Installation of a flat roof on different types of buildings

Depending on whether the room will have a heating system or not, the technology for assembling the roof may differ during installation.

Roofs on unheated premises

Typically, unheated buildings are garages, sheds, gazebos, and various pavilions.

The required slope of 3 degrees on such buildings is formed by the load-bearing roof beams. The height difference is about 30 millimeters per 1 meter of beam length.
After laying the beams, a flooring is made that will serve as a base. These can be boards or profiled sheets. They are secured with self-tapping screws or other suitable fasteners.
If the room is unheated, you may miss a layer such as thermal insulation. Waterproofing material is laid on the base. Roofing felt is used as a waterproof coating. It is spread in overlapping strips (about 150 mm) and additionally fixed with slats, which are placed along the slope of the roof.

This is the simplest version of a flat roof, which can be mounted on a utility unheated room with your own hands at a minimal cost of money and time.

Assembling a flat roof on heated buildings

In residential buildings with a heating system, the roofing pie of a flat roof will be different. Here you will definitely need a thermal insulation layer, high-quality hydro- and vapor barrier. The presence of the latter is no less important, since water vapor can gradually ruin the entire roofing pie.

The floor under the base is assembled from wooden beams, which are placed at intervals of 900-1000 mm.
They are covered with flooring made of boards with a cross-section of 40-50 millimeters. The thickness of the lumber is selected depending on the distance between the beams. The larger it is, the thicker the boards are needed.
Roofing felt is laid on the flooring, it is cut and straightened in advance. Waterproofing sheets are laid with an overlap of about 100-150 mm.
The thermal insulation layer can be made using the bulk method. To do this, fill the resulting base with a layer of expanded clay up to 300 mm and level it.
Next, a cement-sand screed (minimum 30 mm thick) is poured onto the layer of thermal insulation backfill.
After the cement has hardened, the surface is covered with bitumen-based soil and covered with a layer of roofing material.

You can also install a more solid roof made of monolithic concrete.

Monolithic concrete flat roof

In this option, you make a durable concrete base with your own hands.

An I-beam is used as support beams, which are laid level without forming a slope.
For pouring, you will need to prepare concrete of a grade not lower than M250; it is prepared in a concrete mixer, maintaining a ratio of 4:1.5:1:1, where the ingredients are crushed stone (20-25mm), cement (m400), water and sand, respectively.
For pouring, a base is made of boards, which are mounted on the lower flanges of I-beams and covered with roofing felt.
Fine crushed stone is poured on top of the waterproofing, which is filled with the resulting concrete. The filling must be done at one time, otherwise the structure of the roof will not be the same.
Next, expanded clay is poured in and a slope is made.

Leaning

Sloping is the formation of slight slopes on the surface of a flat roof, which allows water to be removed from its surface. The drainage system is assembled in two versions: external and internal. That is, the trays can be attached to the end of the roof or on its surface.

If the drainage gutters are located internally, the presence of drainage basins is planned in advance, the number of which is calculated as follows - 1 funnel per 25 square meters of roof area.

The slope can be formed in the following ways.

When filling expanded clay, plan the required slope. After which the bulk material is filled with a cement screed.
If a heat insulator is used in the form of cotton wool or polystyrene foam, its sheets are positioned so that they form the required slope of the plane.
For a monolithic concrete roof, pouring is carried out in such a way as to form the required slope of 3 degrees.

The entire unbending process should be planned in advance and a preliminary drawing diagram should be made. If you do not maintain the required slope, the accumulated water will gradually ruin the entire roofing pie, negating its protective function.

Many people are accustomed to thinking that flat roofs are usually erected only on multi-story buildings and industrial buildings. However, recently this type roofing has increasingly become used in the construction of private houses. A flat roof in a private house can be constructed without difficulty, taking into account modern technologies and a variety of building materials.

There are 4 types of them:

Exploited. The main feature of this type is a sufficiently powerful base, otherwise there is a risk of damage to the waterproofing layer. Corrugated sheeting or concrete screed acting as a base allows you to create the necessary slope for arranging a drain. Thermal insulation on such a roof must be resistant to serious loads. This is all done in order to use the roof of the house in some capacity, be it a work platform or a recreation area.
Unexploited. Here, the rigidity of the base of the flat roof structure is not as important as in the above option. And the strength of the insulation also does not play a significant role. This roof is cheaper than the one in use, but it will also last a shorter period of time.
Traditional. A feature of their design is the periodicity of layers - waterproofing goes above thermal insulation. Here there is a reinforced concrete slab at the base, and an inclined expanded clay concrete screed is used for drainage.
Inversion. The installation of a flat roof in this embodiment has virtually no problems with water leaks. Here the thermal insulation is located above the waterproofing, which gives the latter protection from ultraviolet rays and the effects of temperature fluctuations. This roofing arrangement turns out to be the most durable and functional, which opens up a lot of possibilities for using the roof space.

Important! Angles in the range from 3 to 5 degrees are considered optimal for the slope of an inversion type of flat roof.

Advantages and disadvantages of this design

A flat roof in a private house, like other types of roofs, has a number of pros and cons. It is worth considering the advantages that determine its popularity in modern construction:

Smaller area than other types of roofing – which saves effort and money;
Convenience and safety of work - it is quite difficult to fall from a straight horizontal surface, but all necessary tools are at hand;
Fast construction - as a consequence of the first two advantages, such work is done much faster;
Ease of maintenance and replacement of roofing - worn parts are usually not dismantled, but a new pie is laid directly on the old one;
The use of additional territory - the arrangement of an exploitable roof opens up great prospects;
It is possible to install transparent roof elements - the view of the open sky on the ceiling is extremely tempting for many;
Giving your home clear geometric shapes - if the house drawing allows, then you can give it a unique look with the help of such a design, especially considering that minimalism is now extremely popular.

It is also worth mentioning the disadvantages of this design:

Snow and leaves accumulate periodically - sometimes mechanical cleaning of the roof is required;
A more complex structure - the presence of drains implies their inevitable blockages, especially in bad weather;
Regular monitoring - the moisture content of the insulation and the general condition of the roof must be constantly checked;

It is not surprising that some people may have doubts about the reliability of this type of structure. But judging by the experience of owners of private houses with similar roofing both in Russia and abroad, this type of roofing successfully functions and pleases its owners.

DIY flat roof installation

Now on the Internet you can find many photos of houses with flat roofs of a wide variety of designs. Interested in the question of how to make a flat roof with your own hands? Before you build a roof, you must first familiarize yourself with the drawing of the house and make sure of its technical characteristics.

The design features of a flat roof depend on many factors. If this is an unheated room and the roof is being erected with your own hands, then it is enough to install support beams, on which a base of uncut boards fastened with screws or nails is then laid. When installing a flat roof on a garage, roofing felt is often used as waterproofing due to its low cost. Apply strips of roofing material in the direction of the roof slope, securing them with wooden or steel slats. Creating a do-it-yourself flat roof for an unheated room is quite easy - here all the work can be done by one person without any help.

When installing a flat roof on a private house, which is planned to be heated, is familiar next order works:

Installation of floor beams. Strict adherence to horizontal alignment is necessary. Here and in subsequent stages, the participation of several workers will be required.
Flooring installation. Usually an uncut board with a thickness of no more than 5 cm is taken.

Important! The size of the lumber cross-section increases in proportion to the distance between the support beams.

Laying waterproofing.
Laying thermal insulation. In this case backfill insulation reinforced with a concrete screed, which dries for a couple of days.
After the screed has dried, a bitumen-based primer is applied to it, then roofing felt is laid and glued.

The structure of the roofing pie

In order to make the roof reliably protected from moisture, it is necessary to place materials in layers one above the other - this arrangement is extremely important. The standard base is made of concrete slabs or professional metal. It is able to withstand the weight of the entire structure above, transferring it to the load-bearing partitions, which, in turn, transfer it to the foundation of the house.

Important! The roof in use must have the strongest possible foundation.

Then come the standard layers: vapor barrier, thermal insulation and waterproofing. When choosing a flat roof roof, you should be guided by the preferences of the owner and the capabilities of the building itself. From a huge cottage to a small one cozy house built many years ago - houses with a flat roof will be reliably protected from various influences environment for many years.

Architects and developers are attracted to these unusual buildings, where you can equip an observation deck or even set up a real hanging garden. Of course, in practice everything turns out to be more complicated than in theory.

Designing a flat roof raises many questions regarding its cost, choice of materials for insulation and waterproofing, organization of water flow, maintenance, etc. Finding answers to them is not so easy. The fact is that domestic contracting companies working in the field of cottage and rooftops are well familiar with the most popular design - pitched, but, as a rule, they have no experience in constructing flat roofs, which are designed completely differently.

Flat roof cost

What immediately attracts attention is the fact that the area of a flat roof is smaller than a pitched roof, which means that less materials will be required, and the work will be cheaper. However, this statement is only true for regions with a warm climate and low snow load, especially if we are talking about an unused roof. In central Russia, to ensure the reliability and durability of a horizontal roof, it is necessary to apply rather expensive engineering solutions.

Beam floor

In principle, when constructing a floor, you can use a combination of beams (wooden, steel) and load-bearing corrugated sheeting. However, experts do not recommend using wooden beams(except for those made of LVL timber with a cross-section of 200 × 100 mm) in regions where the snow cover pressure exceeds 1.2 kPa (about 120 kgf/m2) - that is, in most of the territory of the Russian Federation. A roof covering made of steel I-beams and corrugated sheets with a wave height of 60 mm and a wall thickness of 0.7 mm allows you to cover a span of up to 12 m and can withstand a pressure of at least 6 kPa. But in general, it is less durable than concrete, and is relatively rarely used in individual construction. It makes more sense to use corrugated sheets as permanent formwork, which, by the way, does not replace the need to build a reinforcement cage.

It turns out that 1 m2 of flat concrete or steel base, load bearing capacity which will allow you to withstand the weight of the snow cover, costs 2–2.5 times more than a wooden beam structure of a pitched roof. The difference in the volumetric consumption of insulation is leveled due to the fact that a flat roof requires more expensive high-density material. There is still hope to save on roofing, however, modern polymer membranes - optimal waterproofing for horizontal roofs - they are no cheaper (and sometimes much more expensive) than flexible tiles. There is no need to install snow guards, but you cannot do without a roof hatch and a drainage system. If you try to cut costs according to the estimate, you will subsequently have to pay the price of having to repair the roof every 10–15 years.

The durability of a flat roof largely depends on the ability of the load-bearing base to withstand operational loads without significant deformation

Finally, it should be noted that flat roofs are only suitable for houses modern architecture- with a large glazing area and sophisticated finishing with the latest facade materials. Both will not be cheap at all.

On a solid foundation

As a rule, in low-rise housing construction, the flat roofing is a prefabricated or monolithic reinforced concrete slab. Iron concrete plates(PB, hollow PC, PV, etc.) are capable of covering a span of up to 9 m in length and can withstand pressure of 8, 9 or 12.5 kPa (this value is indicated by the last digit in the product labeling). They can serve as a “base” for any roofing pies, including top layer from paving slabs or fertile soil. However, to install the structure, it will be necessary to ensure that a truck crane can enter the site (while steel beams and flooring can be easily lifted using winches). The depth of support of the ceiling on the wall depends on the material of the latter - for example, for brick this parameter should be equal to the thickness of the slab. Before proceeding with the installation of the roof, it is important to seal the joints of the elements with mortar and additionally seal them with elastic polymer tape.

The main advantage of membranes based on artificial rubber is that they retain elasticity at low temperatures, that is, they can be installed in winter

Classification of flat roofs

Flat roofs are divided into unused and used. The former visit only for inspection, prevention and repair; for this purpose, a roof hatch is installed, to which it leads attic staircase. The roof in use in cottages most often serves as a terrace, that is, a durable wear-resistant coating must be laid on it, and the load-bearing base is designed for increased loads. A type of exploitation is a roof with landscaping, laid with a turf layer on top of the main heat-waterproofing pie; Usually there are paths and a recreation area on it. A convenient exit to the roof in use should be provided, for example from a vestibule superstructure.

A monolithic reinforced concrete floor is erected from heavy concrete using removable (for example, from OSB boards on jack stands) or permanent (from corrugated sheeting) formwork. It is reinforced with a two- or four-level welded frame made of rods with a diameter of 12 mm. The dimensions of a monolithic slab are not regulated (unlike a prefabricated one), which provides the architect with freedom when designing a building; other advantages are the absence of seams, the comparative simplicity of the installation of passage units (chimney, ventilation ducts) and high load-bearing capacity (subject to compliance with technological regulations).

Roof protection from cold and heat

In the low-rise sector, mostly flat roofs without attics are in demand, because the attic requires additional costs and disrupts the architectural proportions of the house. This means that the roof must protect against winter cold and summer heat. A common feature of flat roofs is that the heat-insulating layer is located on top of the supporting structure (in pitched roofs it is usually located between the rafters). If you insulate the room from below, the dew point may shift into the thickness of the ceiling, which will lead to a reduction in the service life of the latter.

Mastics should be used primarily on roofs of complex configurations

As for roofing options, there are dozens of them. Suffice it to say that more than 40 “recipes” are given in SP 17.13330.2011 alone. At the same time, companies producing coatings and insulation materials are offering more and more new engineering solutions. However, they are always based on one of two fundamental schemes - traditional or inversion.

TechnoNIKOL roof installation diagrams

“TN-ROOF Terrace”: 1 - ceiling; 2 - vapor barrier; 3–5 - EPPS (including the slope-forming layer); 6 - fiberglass; 7 - LOGICROOF V-GR membrane; 8 - geotextile; 9 - tiles on supports

Traditional design in general outline is as follows: a vapor barrier film (polypropylene, polyethylene, butumen-polymer) is laid on top of the load-bearing base, followed by insulation, for example - slabs of mineral wool, having a compressive strength at ten percent deformation of at least 30 kPa, in one or two layers with a total thickness of 200 mm. Located above separation layer(for example from polyethylene film), along which a reinforced slope-forming screed is poured (a flat roof must be given a slope of 2–3% towards the center or edges to ensure water drainage). The dried screed serves as the basis for a roll or mastic waterproofing coating.

“TN-ROOF Green”: 1 - overlap; 2 - ramp made of expanded clay; 3 - reinforced screed; 4 - bitumen primer; 5 - “Technoelast EPP”; 6 - “Technoelast Green”; 7 - geotextile; 8 - EPPS; 9 - PLANTER GEO membrane; 10 - fertile layer

Other options are also possible. For example, a slope-forming screed can be located at the very bottom of the pie; in this case roofing waterproofing fixed with gravel ballast, paving slabs on supports or special dowels. Some materials, say the “RUF SLOPE” system (Rockwool) or “TechnoNIKOL Slope”, allow you to do without a screed altogether: the slabs have variable thickness, and with their help it is not difficult to create smooth changes in level to ensure water drainage.

An inversion roof is designed differently: in it, insulation resistant to constant exposure to water (usually extruded polystyrene foam - EPS) is located on top of the waterproofing. At the same time, the latter is reliably protected from mechanical damage and is located in the positive temperature zone (freezing-thawing cycles are destructive for almost any material). It is easy to turn an inversion roof into a usable one, for example by filling in insulation drainage layer sand gravel and laying paving slabs. The disadvantages of the design include more complex drainage. However, we need to talk about gutters separately.

There are special requirements for thermal insulation for flat roofs. The material must not only have a low thermal conductivity coefficient, but also have good resistance to mechanical loads - both distributed (pressure from the overlying layers of the roofing pie, equipment, snow) and local ones that arise during installation. In addition, it is important that the material has hydrophobic properties and is non-flammable. At the moment, there are several ways to install thermal insulation: using mechanical fasteners, adhesive and free laying. In addition to traditional two-layer insulation, single-layer installation is becoming an increasingly popular solution. Rockwool offers unique dual-density slabs that consist of a rigid top layer and a lightweight bottom layer, which speeds up work and improves its quality.

Grigory Gromakov

Specialist in development of the “Flat roofing” direction of the ROCKWOOL company

Water drainage on a flat roof

The flat roof is equipped with a parapet (attic) 30–90 cm high, which helps ensure an organized roof; on a roof in use it also serves as a safety fence. At the same time, the design of gutters should be approached very responsibly, because in case of an error, a huge puddle can form above your head, which can also lead to damage to supporting structures.

As a rule, the choice is made in favor of an internal drain. Such a system is less exposed to the atmosphere and is therefore more durable and reliable than an external one. Let's talk in more detail about its main elements.

Water intake funnels are installed on low areas of the roof. As a rule, on roofs with an area of up to 150 m2, two funnels are installed - the main one, connected to the riser, and the emergency one - with water discharged through a hole in the parapet. With an increase in the number of funnels and risers, the reliability of the system increases, but its cost also increases.

For inversion and green roofs, special funnels with drainage rings have been developed to collect moisture from the intermediate layers. Water receivers must be equipped with electric heating based on a self-regulating cable - then they will properly perform their function during alternating thaws and frosts.

Traditional covering with external drainage 1 - ceiling; 2 - slope-forming screed; 3 - vapor barrier; 4, 5 - mineral wool insulation; 6 - waterproofing; 7 - drain

In a new type of system, the so-called siphon-vacuum system, special funnels are used to prevent air from being sucked into the water flow. Thanks to them, the speed of fluid movement in the pipe (and hence the throughput of the latter) increases, which makes it possible to reduce the diameter of the system elements. However, for low-rise buildings, the savings turn out to be insignificant; moreover, such systems require more accurate calculations than gravity systems.

The drainpipe is made from sewer pipes - polypropylene, polyvinyl chloride, and it makes sense to use sound-absorbing products, for example RAUPIANO Plus (REHAU), or soundproof the riser, otherwise you will hear the murmur of water for hours. The riser is connected to the funnel using an elastic coupling. When laying pipes, the number of bends and the length of horizontal sections, which reduce the throughput of the system, should be minimized.

A drainage pipe laid in the basement or insulated underground connects the riser to the rainwater drainage system or ensures the discharge of water into a linear drainage tray. In the second case, there is a risk of clogging the outlet with ice, so the riser should be equipped with a “winter” outlet to the domestic sewer (the latter should be equipped with a water seal). The outlet pipe is cleaned through a collapsible connection or an inspection module.

Drawing: Vladimir Grigoriev/Burda Media

Inversion roof covering with internal drainage 1 - screed; 2 - PVC membrane; 3 - EPPS; 4 - funnel with drainage ring; 5 - drainage membrane; 6 - sand; 7 - paving slabs

When choosing the standard size of elements of a traditional gravity system, they proceed from the intensity of rain in a given area, focusing on SP 32.13330.2012.

The external drainage system is more vulnerable than the internal one, and also affects the appearance of the facades, but it does not require holes in the roof and ceilings and does not eat up the usable area of the house. Water is discharged through parapet funnels or pipes embedded in the parapet, under which classic funnels (like on a pitched roof) and down pipes attached to the walls with brackets are installed. When calculating, it is assumed that for every square meter of roof area there should be 1–1.5 cm2 of the cross-section of drainpipes. Elements outdoor system can be made of PVC, steel, copper, zinc-titanium.

For roofs in use, as well as roofs installed in regions with harsh climatic conditions, the inversion scheme is ideal. Since the waterproofing layer is located under the thermal insulation layer, it is protected from mechanical influences, as well as from temperature changes and UV radiation, which significantly extends the service life of the roofing system. Waterproofing materials based on modified bitumen must be laid in at least two layers - this technology is more common, and in addition, it allows you to level out possible mistakes when fusing the material. For a polymer membrane, one layer is sufficient, and reliability is ensured by automatic welding equipment, which greatly increases the speed of work. In addition, when installing a polymer membrane, an open flame is not used, so the technology is considered safer.

Dmitry Mikhailidi

Head of the Engineering and Technical Center of the Technical Directorate of the TechnoNIKOL Corporation

Roof landscaping

Since ancient times, turf-covered roofs have been used in countries with moderately cold and humid climates, and the green carpet performed the main moisture-protective function in them.

As part of the modern concept of a green roof, a layer of fertile soil with plants is needed to give unusual features to the appearance of the building, decorate the terrace roof and extend the life of the coating by protecting it from ultraviolet rays. In addition, it absorbs rainwater, unloading gutters, dampens the sound of rain, and protects premises top floor from overheating in summer and reduces heat loss in winter. It is believed that landscaping almost doubles the life of a roof. Its disadvantages include increased load on bearing structures buildings and increasing construction costs. In addition, a green carpet needs care, the intensity of which depends on the selected plant species. If you do not pay due attention to the plants, they will freeze and die from drought.

To green the roof, you should lay on top of the main waterproofing layer (in an inversion scheme - on top of the insulation) an additional cake made of materials that will ensure protection of the waterproofing layer from roots, filtration and drainage of rainwater. For these purposes, special films, dense geotextiles, gravel bedding or drainage and moisture storage membranes made of high-density polyethylene, for example PLANTER GEO or Delta-Floraxx, are used.

Then a mixture of minerals and fertilizers is poured - the so-called soil substrate. You can prepare it yourself by adding fine expanded clay (5–15%), sand (about 20%) and fertilizers to a light soil mixture of neutral peat. As for plants, the easiest way is to limit yourself to meadow forbs and drought-resistant ground covers - sedum, herbaceous carnation, thyme. They do not need to organize an irrigation system, and the thickness of the soil layer can be only 6–12 cm (this type of roof is called extensive). If you plan to walk along the roof among ornamental shrubs, you will have to provide watering and increase the soil thickness to 20–40 cm. Such a roof is called intensive; it creates a significant additional load on the floor, so it must be provided for at the design stage of the building.

The terrace design provides convenient communication between the living quarters of the cottage and the exploited roof, which serves as a resting place

No leaks

Sheet and piece coverings are unsuitable for flat roofs: water will inevitably seep through the joints of the elements. Therefore, roll materials and mastics are used. Let us give a brief description of them.

Roll reinforced polymer-bitumen roofing . Mechanical strength These materials are several times higher than roofing cardboard (, roofing felt). And modifying additives increase resistance to moisture, air and ultraviolet radiation. The material is glued to the base with mastic, fixed mechanically or (most often) fused. There are coatings for the lower layers of the roof (Tekhnoelast EPP, Uniflex EPP, Bireplast TPP, etc.) and for the upper layers (Tekhnoelast EKP, Uniflex EKP, Gidrostekloizol TKP, etc.). The latter are sprinkled with mineral chips, which reduce the risk of fire and additionally protect against mechanical damage and UV exposure. The cost of waterproofing of both types is low - from 65 and from 150 rubles, respectively. per 1 m2, and the average service life of a roofing carpet is 15–30 years.

Rolled PVC membranes , for example, Sikaplan WP, Logicroof, Ecoplast are strong and durable (up to 30 years without repair) and do not support combustion. However, they require a professional approach to installation (the joints of the strips must be carefully welded with hot air) and are relatively expensive - from 320 rubles. for 1 m2. It is important to consider that this material does not tolerate contact with bitumen.

Rolled membranes made of ethylene-propylene rubber (EPDM) and thermoplastic polyolefins (TPO) , for example Firestone RubberGard, Logicroof P-RP, retain elasticity when negative temperatures. Note that EPDM membranes are highly flammable (class G4) and are designed mainly for use in the construction of an in-use roof, where the waterproofing is covered with tiles, gravel or soil. EPDM and TPO membranes cost 1.3–1.5 times more than polyvinyl chloride membranes (mostly imported products).

Polymer-bitumen mastics They allow you to create a seamless coating, but they can only be applied to a durable, non-cracking base - a floor slab or a carefully reinforced screed, and this process is quite long and labor-intensive. The service life of a two-layer coating with a thickness of 5 mm is about 20 years, the price is from 120 rubles. for 1 m2. In practice, mastics are used mainly for roof repair and gluing roll materials.

Polymer and cement-polymer self-leveling waterproofing , say Aquascud, Osmolastic, Osmoflex, is highly elastic
and UV resistance. To improve performance, materials are used in combination with special primers and lining films, and reinforced with mineral fiber (all components are supplied as a single system). The estimated service life of the coating is more than 50 years; price - from 700 rub. for 1 m2.

Flat roof: a pragmatist's view

Advantages	Flaws
Eliminates snow avalanches and reduces the risk of falling ice.	Requires significant costs to construct a foundation with high load-bearing capacity.
Provides convenient access to chimneys, ventilation risers, antennas; Compared to pitched ones, it is easier to maintain and repair.	It is more susceptible to atmospheric factors than pitched, so durability is guaranteed only if expensive materials are used.
Can serve as a recreation area or terrace.	Requires increased attention to the arrangement and condition of the drainage system (especially with internal drainage).
Slightly less susceptible to wind loads than pitched.
Allows you to implement the principle of phased modular construction (to make an extension to a house with a pitched roof, you need to solve a difficult architectural and design problem).

A house with a flat roof, in a row of similar “boxes” with a pitched roof, looks fresh and unusual. Therefore, every year the number of suburban residents who are seriously considering the construction of such a house for permanent residence is increasing. Fans of “cubic” design are captivated by the wow effect and increased attention from neighbors. Someone wants to place it on the roof engineering equipment, or lay out a lawn and arrange seating areas. Still others believe that building a house with a flat roof is cheaper and easier than with a pitched roof. Is it really? Let's consider the main pros and cons of these buildings and draw a conclusion whether they are suitable for our country. To do this, we will answer the following questions:

Why is it difficult to choose a suitable plot for a “cubic” cottage?
Is it true that flat roofs are not suitable for our climate?
Why does a flat roof leak?
A flat roof is simpler and cheaper than a pitched roof - this is a myth
Why is a flat roof difficult to repair?

1. House with a flat roof and domestic realities

Most country residents look at cottages with flat roofs with skepticism, calling these houses “boxes”. Why? Houses with flat roofs came to us from abroad. Traditionally they were built in countries with warm climate, where there is practically no winter, heavy snowfall, severe frosts with sudden thaws, prolonged rains, but strong winds blow. For example, somewhere on the Mediterranean coast. Then these houses turned into fashion design The erotic trend is “not for everyone” in Western Europe, and from there they have already come to us.

Tretin User FORUMHOUSE

I see that we mainly build houses with a pitched roof. But is this really necessary? In Germany and Switzerland, designs for houses with flat roofs have long been offered. What could be the disadvantages of a flat roof, besides the supposed unaesthetic appearance?

Indeed, how can anyone be left indifferent by a cottage with panoramic windows in the photo below?

Or this high-tech house with a flat roof in the forest.

Or a cottage with an observation deck on the roof, a lawn and a place to relax.

Now imagine these houses here. Harsh winter. In an ordinary - not elite village, where roads float in spring and autumn, and areas are fenced with corrugated sheets. Most houses are finished with siding or lined with facing bricks. And pitched roofs are covered with slate, metal tiles or, less commonly, a more expensive solution - flexible tiles. The picture doesn't add up. Something's missing, isn't it? I no longer want to sit on the flat roof of a house, as I dreamed of, with a cup of tea or coffee. After all, the view from there is not of the ocean, sea, mountains or untouched nature, but of dense village buildings or, at best, fields overgrown with grass.

A house with a flat roof, in a high-tech style, looks advantageous only on a spacious isolated area, for example, on a slope, with beautiful view to a forest, lake or river. A cottage with a flat roof is lost without landscape design, and among good-quality, but similar houses, it looks like a “black sheep.”

This is where it lies the first “pitfall” - dreams of a stylish house with a flat roof are shattered when you realize,how much will the plot cost?, on which the cottage will look just right.

Having conceived the construction of a house with a claim to a non-standard foreign design, select an appropriate site for it.

2. Reliability of a flat roof in our climate

When you look at beautiful houses, which are hundreds of years old, ask yourself why they were built this way and not otherwise. Why do houses built in a coastal area somewhere in Norway, Sweden or Scotland do not have roof overhangs and the usual drainage? They are simply not needed because strong winds, which turn rain into a horizontal stream of water hitting the walls. The same goes for houses with flat roofs. They were built in warm climates, where there is little precipitation but strong wind load.

A flat roof is more wind resistant than a pitched roof.

Dmitrievich-50 User FORUMHOUSE

Our ancestors are smart people. They considered the design of the house from the point of view of practicality, based on the climatic conditions of their residence. Why were flat roofs built in Central Asia? On the Central Russian Upland are they sloped? In the Baltics, not just pitched ones, but with a sharp ridge angle? A pitched roof with a slope of 45 degrees, in the Moscow region or Saratov, will provide reliable protection from rain or snow for 20-25 years, even if covered with cheap corrugated board or slate.

Flat roof, with the right approach to construction and using modern materials, it will also provide reliable protection of the house from precipitation and will not leak.

The only question is how much 1 sq. m. will cost. m of such a roof with a guarantee that it will not leak quickly during frequent transitions through 0. Icing. Night freezing and daytime thawing of snow cover. Lingering downpours. And most importantly - how to make a roof so that it lasts a long time in our climate?

The second difficulty in building a cottage with a problem-free flat roof is the harsh Russian operating conditions.

3. The main problem of building a reliable house with a flat roof in the Russian Federation

link82 Member of FORUMHOUSE

The company built me a house with a flat roof. We made 6 pieces along the edges. heated funnels and led out to the sides, through the parapet, drain pipes. Is it correct? Maybe it was necessary to make a slope to the center and, with a small roof area, install two funnels instead of six? And put the pipe inside the building. Output in the base and further into storm sewer? I am afraid that the knee that is being taken out of the funnel into the street will freeze. Ice has already formed on the pipes. What if the pipe bursts due to frost? How to fix it? Throw in a heating cable? So much money has already been spent on this roof!

The house with a flat roof was built in 2013.

In addition to problems with drainage, another one was added. When link82 I came to check the house and discovered that the roof was leaking in several places. Water came from the second floor to the first. All the drywall floated. Now you have to quarrel with the builders. Trying to take the money and completely redo the roof. According to Mikhail-snabss(a user of the portal is a professional in the construction of flat roofs) this example contains a whole bunch of errors. The main one is builders who simply don’t know how to make flat roofs correctly.

When building a house with a flat roof, do not go cheap. Every step of builders and stage of work needs strict control. More careful than when constructing a pitched one. Mistakes will be costly!

The roof was most likely made of a built-up waterproofing material - glass insulation. The tree played and the fiberglass tore. Repairing this roof with a special roofing membrane will cost from 130 to 200 thousand rubles.

The third factor complicating the construction of a cottage with a flat roof in the Russian Federation - lack of highly qualified builders who know exactly how to build just such houses correctly. How to use and combine materials with each other. What tools are needed for this? Even if the future owner of a house with a flat roof has a detailed design, and he should be, then everything can be ruined by “specialists” who work on the principle: “we always build this way and no one has complained yet!”

Flat roofing should only be done by professionals.

4. Is a flat roof cheaper and simpler than a pitched roof?

Usually, when it comes to the advantages of a flat roof, you can hear the argument that it is cheaper than a pitched roof. Why? Smaller area- less consumption of materials. It’s easier to make an overlap, because no need for classic rafter system. No need to arrange attic floor etc. And that's true, but as they say, the essence is in the details.

If we take a simplified look at the “pie” of a flat roof, then the following are laid on the base, for example concrete floor slabs:

vapor barrier;
thermal insulation;
waterproofing.

Or the so-called inversion flat roof, where the layers go like this:

waterproofing;
thermal insulation;
finishing layer.

In an inversion flat roof, the waterproofing layer is located under the insulation and “works” in more gentle conditions, because from above, from negative influence weather conditions, it is protected by crushed stone, tiles or soil with a lawn. Those. a ballasted flat roof is installed.

But, when building a flat roof it is necessary:

Arrange slopes for water drainage - about 2 cm per 1 linear meter. Slopes are usually made with concrete screed or wedge-shaped insulation elements.
Lay several layers of insulation. If used stone wool, rather than extruded polystyrene foam, install aerators to remove water vapor from the thermal insulation.
Put water intake funnels with electrically heated , otherwise, due to the ice that has formed, they will not drain water from the roof.

One water intake funnel, with a diameter of 110 mm, drains water from an area of up to 300 square meters. m.

Install a drainpipe with a slope of 3 cm per 1 linear meter.
Make high-quality waterproofing from PVC, TPO or expensive EPDM membranes. TPO membranes are less elastic than PVC membranes, but have higher strength. Welding TPO membranes requires professional installers with special equipment. The advantage of EPDM membranes is their large format, and the fewer welds, the more reliable the flat roof.

When installing a flat roof, you will have to take into account many nuances.

Calculate the snow load depending on your region of residence. For example, Moscow and St. Petersburg belong to the third climatic region. The snow load on a flat roof, with a slope of 2%, in the Moscow region will be 180 kg per 1 sq. m. m. In the fourth climatic region snow load 240 kg per 1 sq. m, and in the fifth there are already 320 kg. Do not forget that the weight of 1 m 3 of loose, freshly fallen snow is on average 50 - 100 kg. Already compacted 350 kg. A cube of wet or melting snow weighs approximately 400-600 kg.

There is no need to remove snow from a properly designed flat roof in winter. The excess is blown away by the wind, and the loose snow becomes a heat insulator.

But the load on a flat roof must be taken into account with a greater margin than on a pitched roof, taking into account force majeure circumstances. For example, the water inlet funnels became clogged, the heating cable burned out, and the water did not drain from the roof. A month's worth of snow fell in a couple of days, but there was no wind to blow it away and it lies on the roof. Additional weight on the roof puts pressure on the walls, which in turn transfer the load to the foundation, which redistributes it to the soil foundation. The further north you go, the greater the load. Add a lot of crushed stone or soil with grass if you are installing a ballasted flat roof.

From here - The optimal design for a cottage with a flat roof is not a frame or wooden house, but a stone structure, calculated by the designer and built from aerated concrete, brick, warm ceramics, using monolithic technology. Because “Cubic” design involves large unsupported spaces, then it will no longer be possible to block a span of more than 6 m with a tree. Trusses, I-beams, wooden I-beams, hollow reinforced concrete floor slabs, monolithic ceiling or prefabricated monolithic floor. Don’t forget to add expensive façade finishing solutions to the cost of a house with a flat roof.

You can't finish a house like this cheap anymore.

Planken, burnt wood, hand-molded bricks are used, wet facade, combined facades made of wood and stone. And you can’t put it in a house with a flat roof. standard windows. Large or panoramic are required. Add to this additional areas parapets, which also need to be insulated and finished. This increases construction costs.

The fourth factor - a house with a flat roof cannot be called budget construction.

Consider the costs not only for the roof, comparing the final estimate with flat and pitched ones, but for the total cost of the entire “box” with finishing.

5. Low maintainability of a flat roof

sv2321 User FORUMHOUSE

I have a house with a flat roof. Waterproofing - membrane. I'm struggling with the roof. As they say, water will always find a hole. I like the flat roof, but I think I’ll give it up and convert it to a pitched roof, although I’ll have to change the entire architecture of the house. And that's why:

There is no absolute guarantee that all joints of a flat roof will be airtight. Enough microcrack and off we go. If there is a slope, then small defects are not critical;
Snow lingers on a flat roof. He's melting. Water fills microcracks. It was frosty at night. The water is frozen. With frequent daily freeze-thaw cycles, microcracks enlarge and then rupture. They are getting bigger. The pitched roof has no welded areas and there is nothing to tear there. In the worst case scenario, a small temporary leak will appear without progressive consequences. It is easy to find and repair;
The most unpleasant thing. On a flat roof, you will never know exactly where the defect occurred. There is a leak in one place, and water is dripping from the ceiling in another. The craftsmen will come, check the joints and find one of the defects, but the rest will remain. If the roof is inverted or loaded with gravel, then defect detection is an even bigger problem.

According to the user, the optimal roof for our climate is pitched. The angles of the slopes compensate for the crooked hands of the builders and changes in the properties of materials over time, and the overhangs protect the walls and finishing from precipitation.

So, fifth - low maintainability. The quality of a flat roof is greatly influenced by the human factor.

If it leaks pitched roof with a cold attic, it is not difficult to find and repair the defective area. As a last resort, you can dismantle the coating and perform local repairs or get to the problem area from the inside. In the case of a flat roof, finding a leak and repairing it becomes more difficult due to the complex “pie”. Many layers in the structure, especially in the so-called. "green roof". Presence of concrete screed, etc.

conclusions

Houses with a flat roof certainly look beautiful and stylish. Make a flat, problem-free roof that will serve for many years in our climate also possible. The only question is the total cost of all decisions and its feasibility. Anyone who has been involved in roof installation or repair in our climate knows that in the summer, a hot roof in the sun is the last place you would want to sit with your family or friends. It's hot and stuffy. I want to quickly go into the shadows. If there are small children in the house, then a used flat roof is an extra headache for parents. You can also organize a shaded private place to relax with barbecue on a small area. It’s nice to sunbathe in the garden on the grass, throwing in a towel or laying out a sun lounger, and not in full view of all the neighbors and passers-by on the roof. In the countryside, you simply want privacy, and not stick out your private life for everyone to see. Let's add our changeable weather. Rain. The wind, which at altitude is felt completely differently than below. In total, how many days a year will there actually be left to relax on a flat roof? Let's add the need to arrange a place to access the roof directly from the house. Do not climb onto a flat roof using a ladder that is attached to the facade. What's left? Unusual “fashionable” design to attract attention. Therefore, let everyone decide for themselves whether to build a house with a flat roof or not, and FORUMHOUSE offers you proven solutions for this.

how to properly build a house in our climate with a roof without overhangs and a hidden drain, and what are its advantages.

Stone house with a flat roof: a harmonious combination of exterior and interior. The video shows the design features of a monolithic stone house with a flat roof and unusual facade decoration.