When building your home, building a roof is one of the most important tasks. We propose to discuss how a flat roof is made in a private house with your own hands from corrugated board, its installation, insulation and drainage, as well as the advantages and disadvantages of this type of roofing.

Design features of a flat roof

Modern private builders rarely use flat roofs to cover private buildings, dwellings, mainly these are surfaces that can be covered with a gazebo, the surface of a garage, a bathhouse and other utility rooms. Mainly a flat roof is used for multi-storey residential buildings, where, due to design features, it is impossible to build a gable roof.

Photo - Flat roof roofing pie

Projects of houses and cottages with a flat roof are distinguished by originality and eclecticism. In addition, you can equip a special roofing cake, thanks to which the lack of attic (inter-roofing) space will play into your hands. There are such types of flat roofs:

Photo - Flat roof waterproofing

There is also a flat combined roof - when the roof combines several of the listed types. For example, inversion and traditional.

pros flat roof:

1. Very simple design, there are no special principles for installing rafters, frames and other beams;
2. Easy calculation of roofing materials;
3. You can use the surface of such a roof as a foundation for installing various systems directly on the roof: satellite dishes, winter gardens, solar panels, etc.;
4. Smaller area, unlike a shed or attic (no need for wide overhangs).

But minuses flat non-attic roof are more significant:

1. Due to the lack of an angle of inclination, it often leaks. Shed, gable and other sloping types of roofs do an excellent job of independently draining water, but for a flat one you need to build a special drain;
2. Several times a year, a country house will need to be cleaned from the accumulation of foliage and snow on the roof;
3. Often the funnels of the internal drain freeze due to the lack of an attic.

But still, in view of economy, the disadvantages that a flat roof has are not very significant compared to its advantages.

Video: flat roof

How to choose a material for a flat roof

Properly selected roofing materials for a flat roof are half the success of the entire house construction. Of course, you can stop at a profiled sheet, but it is worth noting that in this case it is necessary to think about how snow removal and drainage will be carried out. The fact is that from the constant exposure to atmospheric precipitation, the metal coating can rust and go out of service earlier than the period declared by the manufacturers.

The roof covering must be perfectly resistant to moisture. Here will serve well:

1. Decking with a polymer coating;
2. Polycarbonate;
3. Slate;
4. Mastics.

Let's consider what material for a flat roof is more often used. Construction mastics most commonly used on residential buildings. These are special liquid coatings that are applied to the surface of the roof with a brush, and then solidify, forming an airtight solid substance that looks like rolled materials. They perfectly resist high temperatures - up to 70 degrees, but can crack at low temperatures - up to 25.

Photo - Flat roof

Polycarbonate is more reliable and beautiful than mastics, but it is much more expensive. Its main advantage is its external similarity with glass, so it can be used to create a stylish roof that will emphasize your financial condition. In addition, it is polycarbonate that is chosen for the design of residential buildings.

Slate previously used for any type of roof, regardless of its slopes. It is very heavy, so to install it, you need to carefully consider the frame and foundation of the building - so that the house does not "settle". The load that is placed on the rafters by slate is perfectly compensated by its durability indicators: it can last up to 50 years in medium-aggressive environments with strong pressure and temperature drops. Now it can be replaced by aerated concrete, which is lighter.

Decking polymer coated is an almost ideal material for covering a flat roof. A dacha, a greenhouse and a house with such a surface may not be afraid of temperature changes, ultra-low degree indicators, but a snow cushion is fatal for them. It is necessary to ensure that the metal is periodically cleaned of precipitation, so work out natural cleaning systems.

Photo - Flat roof made of corrugated board

More rarely, but still, a wooden flat roof is used. Its durability indicators are relatively low, but the tree will help protect the roofing material or the same mastics. Timber roofs are mainly used in complex design projects.

Flat roof installation

Consider how a flat exploited roof is installed on square houses, as well as how to insulate this type of coating.

A flat roof is a universal type of construction, it has an excellent combination of price and quality, but there are significant drawbacks in the form of a complex gutter system. When choosing such a roof, weigh all the advantages and disadvantages very well.

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Do-it-yourself flat roof - most often located on private low-rise buildings, as well as on garage buildings. This type of roofing device is ahead of its competitors. In our article, we will explain why.

Before we talk about how to make a flat roof, we note that the term "roof" and the term "roof" are not the same thing. The term "roof" refers to those elements that are located above the living quarters of the house. And the roof is a component of the roof, its top layer. It is he who protects the entire building from the effects of atmospheric influence. In these conditions it is very important to create a reliable roof of a country house.

Having familiarized yourself with the difference between the terms, we can state that a flat roof is ideal for a house with a small area. With an impressive roof area, it is recommended to work with the whole team.

Flat roof and its features

When working on a small house with a small roof area, you can safely do without assistants.

At the beginning of work, fasten wooden beams or steel beams to the bearing camps. With the help of them, you can reduce most of the mass of the roof, directing it to the main walls and foundation.

So, we found out that the main load on the beams is the weight of the roof. But besides this, there are other loads, such as:

• The total weight of the roof and communication elements. As a rule, they are located in the attic or attached to the roof.
• The weight of a person who is repairing a roof or roof. It can also install additional hardware.
• Volume and mass of snow + cold winter wind pressure.

Read the advice of experts on the forums, look at the photos on the Internet - then you can make the right choice of load-bearing beams and avoid critical mistakes. Surely you will be interested in the article flat roof - the pros and cons.

If you want to get a reliable and safe flat roof, then choose only the right roofing (details: ""). Also important is the choice of related materials that can withstand heavy physical exertion, as well as the effects of natural disasters.

Don't forget to check all material specifications. To prevent negative consequences - conduct a thorough hydro- and vapor barrier.

1. Lay a "pie" of several materials on the plates (they must have different properties).
2. The first layer is a vapor barrier. Its function is to protect the insulation layer from moisture. As a material for vapor barrier, a polymer-bitumen film is used. At the same time, it is often reinforced with fiberglass, and then a flat roof is installed. Place the edges of the film on the verticals of the overlaps. It is very important to carefully and accurately close the seams, as well as to understand.
3. On top of the vapor barrier, lay the insulation. If expanded clay is used, fill it with a mass of concrete. When constructing a lightweight roof, a polymer insulation must be fixed directly to the vapor barrier.
4. Moisture insulation is the main layer for a roof without slopes. For the device of this element, you will need membrane or polymer-bitumen materials.

Do-it-yourself flat roof for cold rooms

There are buildings that do not have heating. These include sheds and gazebos. They are supposed to create a slope for water flow from the roof. To do this, you only need to equip the roof at the smallest angle.

When constructing a sloping flat roof, its supporting beams should be at a slight angle. Boards will be fixed on the beams. This will be a kind of basis for rolled roofing material (more details: "").

For the installation of a rolled carpet of roofing material, you will need a frame made of boards. For this, it is best to use thin wooden planks or steel strips. Fasten them along the slope. In this case, the step should be 70 cm. But you should not block the path of water flowing from the roof. The percentage of slope of such a roof is no more than 3%. In other words, it is 3 cm per linear meter of length.

Construction of flat roofs for warm rooms

Consider the nuances of equipping a flat roof for heated houses:

1. First of all, lay a layer of boards on the supporting beams, having previously completed. After this, the laying of the roofing or roofing material should be carried out. Their canvases should be placed according to the overlap method. In this case, the length should be 15 cm.
2. Expanded clay is laid on top of the roofing material (you can use slag or other material). Before filling the insulation, check that the slope is directed towards the flow of precipitation.
3. The third stage is the pouring of the insulation layer with cement. After preparing the screed, treat it with a bitumen primer.
4. Only a fully finished screed will be ready to accept rolled roofing material.

When studying flat roof construction, you will see for yourself that roofs with a large spacing between support beams require the participation of several people. It is advisable to invite professional craftsmen who will perform all the necessary work as soon as possible.

When fixing the support beams, the distance between them should be observed. It should be no more than 1 m.

The device of a flat roof made of monolithic concrete

The first step is to calculate the span of the roof. If it is 5 m, then beams of 15 cm are used. Speaking in professional building language, this is the “fifteenth I-beam”.

To create a monolithic roof, it is recommended to use concrete grade 250. When creating a concrete solution at the construction site, it is advisable to use a concrete mixer. Otherwise, you are unlikely to achieve the correct consistency of the solution. To obtain concrete for a flat roof, it is necessary to mix crushed stone with particles of 20 mm and cement, brand PC-400.

When calculating the components, adhere to the following rules: for eight buckets of crushed stone - three buckets of cement, 4 buckets of sand, and two buckets of water. If there is not enough water, you can add more, it is not critical.

Insulation of a flat roof with foam concrete, see the video:

Next, the boards are fastened to the lower beam shelves. Roofing material is laid on the dry surface of the boards. Then, a reinforced mesh of a periodic profile is laid on top. The diameter of this element should not be less than 1 cm. The size of the cells in this case is 20x20 cm.

In order not to repair a flat roof, the places where the mesh rods are laid are fixed with a tie wire. An option using glue is possible. Ultimately, the mesh should not slip when the screed is poured.

For complete coverage with concrete mortar, small pieces of crushed stone are usually laid out at the bottom of the grid. Due to this, a gap of 4 cm is left. It is necessary to distinguish between the grid and the roofing material layer. Filling is carried out in the openings between the beams. Recall that their thickness should be at least 15 cm.

After all the steps, the concrete is covered with a film of polyethylene. This is especially true if the work is carried out at high temperatures. By covering the surface, you will prevent the evaporation of moisture from the concrete solution. This, in turn, will protect the top layer from cracking.

Concrete must be under the film for at least three days. After completely drying the concrete mass, pour a layer of insulation. Don't forget about slopes. The next step is to create a screed and install a rolled carpet.

Insulating a flat roof

Today, a common phenomenon is the replacement of a flat roof with a pitched one. However, in favor of a flat roof is the fact that it can be insulated both from the outside and from the inside. And after it is completed.

Previously, solid slabs of thermal insulation were used for insulation. However, with this option, the roofing weight increased significantly. Having studied past experience, modern construction has moved away from this method of insulation. Today, most often flat roofs are insulated with basalt mineral wool. It's pretty light material. In addition, it boasts good thermal conductivity and moisture resistance.

Note that basalt mineral wool is not subject to combustion processes. In addition, it fully tolerates even the most negative influences of nature.

Architects and developers are attracted by these unusual buildings, where you can equip an observation platform 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, the choice of materials for insulation and waterproofing, the organization of water flow, maintenance, etc. Finding answers to them is not easy. The fact is that domestic contracting firms working in the field of cottage and are well aware of the most popular design - pitched, and, as a rule, they do not have experience in erecting flat roofs arranged in a completely different way.

flat roof cost

Immediately noteworthy is the fact that the area of ​​​​a flat roof is smaller than a pitched one, which means that fewer materials will be required, and the work will be cheaper. However, this statement is true only for regions with a warm climate and low snow load, moreover, if we are talking about an unexploited roof. In central Russia, to ensure the reliability and durability of a horizontal roof, rather expensive engineering solutions are required.

beam ceiling

In principle, when erecting a ceiling, a combination of beams (wooden, steel) and a supporting corrugated board can be used. However, experts do not recommend the use of wooden beams (with the exception of those made of LVL beams 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. Roofing made of steel I-beams and corrugated board 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 withstands pressure of at least 6 kPa. But in general, it is less durable than concrete, and is relatively rarely used in individual construction. It is more reasonable to use corrugated board as a fixed formwork, which, by the way, does not eliminate the need to build a reinforcing cage.

It turns out that 1 m2 of a flat concrete or steel base, the bearing capacity of which will withstand the weight of the snow cover, costs 2–2.5 times more than the wooden beam structure of a pitched roof. The difference in the volumetric flow rate of the insulation is offset by the fact that a flat roof requires a more expensive high-density material. There is still hope to save on roofing, however, modern polymer membranes - optimal waterproofing for horizontal roofs - are no cheaper (and sometimes much more expensive) than flexible tiles. You won’t need to install snow retainers, but you can’t do without a roof hatch and a drainage system. If you try to reduce the cost of the estimate, then later you will have to pay with the need to repair the roof every 10-15 years.

The durability of a flat roof largely depends on the ability of the supporting base to withstand operating loads without significant deformations.

Finally, it should be noted that flat roofs are appropriate only on houses of modern architecture - with a large glazing area and sophisticated finishing with the latest facade materials. Both of these won't come cheap.

On a solid foundation

As a rule, in low-rise housing construction, flat roofing is a prefabricated or monolithic reinforced concrete slab. Reinforced concrete slabs (PB, hollow core PC, PV, etc.) are able to cover a span up to 9 m long and withstand a pressure of 8, 9 or 12.5 kPa (this value is indicated by the last digit in the product marking). They can serve as a "base" for any roofing pies, including those with a top layer of paving slabs or fertile soil. However, for the installation of the structure, it will be necessary to provide a check-in to the site of the truck crane (while steel beams and flooring are easy to lift with winches). The depth of support of the ceiling on the wall depends on the material of the latter - for example, for a 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 an elastic polymer tape.

The main advantage of membranes based on artificial rubber is that they remain elastic at low temperatures, that is, they can be mounted in winter

Flat roof classification

Flat roofs are divided into non-exploited and exploited. The former are visited only for revision, prevention and repair; for this purpose, a roof hatch is equipped, to which an attic staircase leads. The operated roof in cottages most often serves as a terrace, that is, a durable wear-resistant coating must be laid on it, and the supporting base is designed for increased loads. A variety of exploited - a roof with landscaping, lined with a turf layer on top of the main heat and waterproofing cake; usually it is arranged with paths and a recreation area. A convenient exit should be provided for the operated roof, for example, from a vestibule superstructure.

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

Roof protection from cold and heat

In the low-rise sector, mostly non-attic flat roofs are in demand, because the attic requires additional costs and violates the architectural proportions of the house. So, the roof should protect from the winter cold and summer heat. At the same time, 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 the room is insulated 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 configuration

As for the options for the execution of the roof, there are dozens of them. Suffice it to say that only in SP 17.13330.2011 there are more than 40 "recipes". At the same time, companies - manufacturers of coatings and insulation offer more and more new engineering solutions. However, they are always based on one of two fundamental schemes - traditional or inversion.

Schemes of the device of roofs "TechnoNIKOL"

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

The traditional design in general terms is as follows: a vapor barrier film (polypropylene, polyethylene, butum-polymer) is laid on top of the supporting base, then a heater follows, for example, mineral wool boards with a compressive strength at ten percent deformation of at least 30 kPa, in one or two layers with a total thickness of 200 mm. Above is a separating layer (for example, from a polyethylene film), along which a reinforced slope-forming screed is poured (a flat roof must be given a slope of 2-3% to the center or edges to ensure water flow). The dried screed serves as the basis for a rolled or mastic waterproofing coating.

"TN-ROOF Green": 1 - ceiling; 2 - expansion from expanded clay; 3 - reinforced screed; 4 - bituminous 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 placed at the very bottom of the pie; in this case, the roof waterproofing is fixed with gravel ballast, paving slabs on supports or special dowels. Some materials, for example, the RUF SLOPE system (Rockwool) or TechnoNIKOL Slant, allow you to do without a screed at all: the plates have a variable thickness, and with their help it is easy to create smooth level drops to ensure water flow.

The inversion roof is arranged differently: in it, a heater 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 zone of positive temperatures (freeze-thaw cycles are destructive for almost any material). It is easy to turn an inverted roof into an exploitable one, for example, by filling the insulation with a drainage layer of sand gravel and laying paving slabs. The disadvantages of the design include a more complex drainage system. However, drains need to be discussed separately.

There are special requirements for thermal insulation for a flat roof. The material must not only have a low coefficient of thermal conductivity, but also resist mechanical loads well - both distributed (pressure of the higher layers of the roofing cake, equipment, snow) and local ones that occur during installation. In addition, it is important that the material has hydrophobic properties and is non-combustible. At the moment, there are several ways to install thermal insulation: using mechanical fasteners, adhesive and free laying. In addition to the traditional two-layer insulation, one-layer laying is becoming an increasingly popular solution. Rockwool offers unique dual-density boards that consist of a rigid top layer and a lightweight bottom layer to speed up and improve quality.

Grigory Gromakov

ROCKWOOL Flat Roof Development Specialist

Flat roof drainage

A flat roof is equipped with a parapet (attic) 30–90 cm high, which helps to ensure organized; on the operated roof, it also serves as a safety fence. At the same time, the design of gutters should be approached very responsibly, because in the event of an error, a huge puddle can form above your head, which threatens to damage the 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 therefore more durable and reliable than the outdoor one. Let's talk more about its main elements.

Drainage funnels are installed on low sections of the roof. As a rule, two funnels are mounted on roofs up to 150 m2 - the main one, connected to the riser, and the emergency one - with water discharge 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 inverted and green roofs, special funnels with drainage rings have been developed to collect moisture from the intermediate layers. Water intakes must be equipped with electric heating based on a self-regulating cable - then they will properly perform their function during alternating thaws and frosts.

Covering traditional with an external drain 1 - overlap; 2 - slope-forming screed; 3 - vapor barrier; 4, 5 - mineral wool insulation; 6 - waterproofing; 7 - drain

In systems of a new type, the so-called siphon-vacuum systems, 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 gravitational ones.

The drain riser is made of sewer pipes - polypropylene, PVC, and it makes sense to use noise-absorbing products, such as RAUPIANO Plus (REHAU), or to soundproof the riser, otherwise you will hear the murmur of water for hours. The riser is attached to the funnel using an elastic coupling. When laying pipes, minimize the number of elbows and the length of horizontal sections that reduce the throughput of the system.

A drainage pipe laid in the basement or insulated underground connects the riser to the rain sewer or provides water discharge into the 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 revision module.

Image: Vladimir Grigoriev/Burda Media

Roof covering inversion with an internal drain 1 - coupler; 2 - PVC membrane; 3 - EPPS; 4 - funnel with a 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 rains 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 branch pipes embedded in the parapet, under which classic funnels are installed (as on a pitched roof) and downpipes attached to the walls with brackets. 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 of the external system can be made of PVC, steel, copper, zinc-titanium.

For exploited roofs, as well as roofs arranged 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 extremes and UV radiation, which significantly extends the 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 errors during the deposition of the material. For a polymer membrane, one layer is enough, and reliability is ensured by automatic welding equipment, which greatly increases the speed of work. In addition, an open flame is not used when installing a polymer membrane, so the technology is considered safer.

Dmitry Mikhailidi

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

Roof greening

Turf-covered roofs have been used since ancient times in countries with a moderately cold and humid climate, 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 covering it from ultraviolet rays. In addition, it absorbs rainwater, unloading gutters, dampens the sound of rain, protects the upper 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 an increase in the load on the supporting structures of the building and an increase in the cost of construction. In addition, the green carpet needs care, the intensity of which depends on the selected plant species. If you do not pay due attention to plantings, they will freeze and die from drought.

For landscaping the roof, it is necessary to lay on top of the main waterproofing layer (in the case of an inversion scheme - on top of the insulation) an additional cake of materials that will protect the waterproofing layer from roots, filter and drain rainwater. For these purposes, special films, dense geotextiles, gravel bedding or drainage and moisture-accumulating membranes made of high density polyethylene, such as PLANTER GEO or Delta-Floraxx, are used.

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

The terraced structure provides convenient communication between the living quarters of the cottage and the exploited roof, which serves as a place of rest

No leaks

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

Roll reinforced polymer-bitumen roofing . The mechanical strength of these materials is several times higher than that of roofing paper (, roofing paper). And modifying additives increase resistance to moisture, air and ultraviolet. The material is glued to the base with mastic, fixed mechanically or (most often) welded. There are coatings for the lower layers of the roof (Technoelast EPP, Uniflex EPP, Bireplast TPP, etc.) and for the upper ones (Technoelast 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.

Roll membranes made of ethylene propylene rubber (EPDM) and thermoplastic polyolefins (TPO) , for example Firestone RubberGard, Logicroof P-RP, retain elasticity at low temperatures. Note that EPDM membranes are highly flammable (class G4) and are mainly designed for use in the construction of an exploited 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 ones (mostly imported products).

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

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

Flat roof: pragmatic view

Advantages	disadvantages
Eliminates snow avalanches and reduces the risk of ice falling.	Requires significant costs for the construction of a foundation with a high bearing capacity.
Provides convenient access to chimneys, ventilation risers, antennas; compared to pitched, it is easier to maintain and repair.	More exposed to atmospheric factors than pitched, so durability is guaranteed only if expensive materials are used.
Can serve as a recreation area, terrace.	Requires increased attention to the arrangement and condition of the drainage system (especially with internal drainage).
Somewhat 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).

If earlier flat roofs were made only on urban high-rise buildings and were associated with constant leaks, today the situation has changed radically. These structures are used not only during the construction of multi-storey buildings, but also in the construction of prestigious private houses according to exclusive projects. Such changes have become possible due to the emergence of completely new building materials and technologies.

Flat roofs - one of the many types of roofing, has both positive and negative sides. The advantages of such roofs include the following characteristics.

1. Saving building materials and speed of construction. The effect is achieved due to physical savings - the area of ​​\u200b\u200ba flat roof is much less than a gable roof. In addition, for this design there is no need to make a complex truss system with various girders, props, crossbars, mauerlats, etc. A small number of roof elements makes it possible to build flat roofs on your own without involving expensive professional specialists.
   True, for this you should have the initial skills of performing roofing work, understand modern technologies and materials. Otherwise, attempts to reduce the estimated cost of the structure can lead to large additional costs for unplanned repairs. And not only the roof itself, but also the interior of buildings.

   

2. The ability to use the roof as exploited. On flat roofs, winter gardens, recreation areas, flower beds, small sports grounds, etc. can be equipped. But in these cases, the roofs have a very complex structure and require a professional approach to all construction work.

   

3. Flat roofs facilitate installation and periodic maintenance various engineering equipment: air conditioning and ventilation systems, solar panels, antennas, etc.

   

Unfortunately, such architectural structures also have disadvantages.

We have listed the real advantages and disadvantages, each developer should carefully analyze them before making a final decision.

Varieties of flat roofs in private houses

Thanks to new materials and technologies, designers have been able to create several types of flat roofs with unique performance characteristics.

flat roof type	Brief description of technical and operational characteristics
	The most commonly used, simplest and cheapest type of roof. It is most often found on utility buildings, it is rarely mounted on private houses.
	Very prestigious roof, allows you to use the area to increase the comfort of living in the building. The arrangement of such roofs requires high-quality materials and special technologies. The operated roof is often inverted.
	It differs from the usual arrangement of layers of the roofing cake. Waterproofing is done directly on the bearing base, this feature protects the coating from mechanical damage. Geotextiles, extruded polystyrene foam, another layer of geotextiles and a ballast layer are laid on top of the hydroprotection. The geotextile allows water to flow to the drain system, and the ballast prevents the layers from being blown up by strong gusts of wind.

Important. The cost of flat roofs varies widely, some options for the price can be several times higher than gable structures.

Roofing pie device

All flat roofs in residential buildings must be insulated, the structures consist of several layers. Each of them performs its function and is critical for the roof.

Base

It can be reinforced concrete or wood.

Professional builders prefer reinforced concrete slabs, but not all houses can use them. Plates are mounted only on brick or concrete facade walls; such elements are not used for wooden or frame buildings.

vapor barrier

Prices for material for vapor barrier

Vapor barrier material

It is used only in two cases: the base of the flat roof is wooden and mineral wool is used as insulation.

But such options are rare, most often the base is made of a concrete slab, and durable extruded polystyrene is used for insulation. Both of these materials are not only not afraid of steam, but also do not react to direct contact with water. Accordingly, when arranging roofs from such materials, vapor protection is not required.

insulation

There are two types of insulation that can be used in the construction of flat roofs.

Heaters can be installed in two ways.

Currently, architects in most cases prefer the second option for flat roof insulation, keep this in mind. But practitioners advise installing heaters from inside the premises. Each builder must make their own decision.

Prices for thermal insulation materials

Thermal insulation materials

Practical recommendations for arranging a flat roof on a frame house

For example, we will take the option of arranging a flat roof on a wooden frame house. These buildings are very popular with many developers, they are quickly assembled, relatively inexpensive and provide residents with a modern level of comfort.

How to make overlays

For the ceiling, you need to use I-beams, ordinary beams will not work because of very high loads. If the linear dimensions of ordinary beams are significantly increased, then their own weight will play a significant role in calculating the acting forces, and this is highly undesirable for all structural loaded elements.

Important. If the size of the house is large, then it is much more profitable to order short beams and splice them on the spot. Due to this method, the process of transportation and installation of structures is simplified. During the installation of ceiling beams, you need to make a slight slope for the water to drain.

Video - Wooden floor

What to make waterproofing

Prices for PVC membranes for roofing

PVC membrane for roofing

For sealing, it is recommended to use a modern high-quality membrane that has protection from the harmful effects of ultraviolet rays. The membrane thickness is not less than 1.5 mm, the service life of such coatings is more than thirty years. The membranes must retain their original properties at temperatures of -30°C and below. It must be borne in mind that situations may arise when it is necessary to remove snow from the roof in winter, the hydroprotection must withstand mechanical stress and not be damaged.

How to install a funnel for receiving water

The diameter of the funnel must correspond to the area of ​​​​the roof and the maximum debit of water. The data are available in comparative tables and are attached to the instructions for using the elements. If for some reason there is no such instruction, then you should consult with the seller.

The funnel is installed at the lowest point of the roof. The roof plane is divided into several sectors and each has a slight slope towards the drain. To prevent ice from accumulating in the funnel in winter, it is recommended to connect an electric heating system. Heating functions temporarily and only during the period when the temperature changes from positive to negative several times a day.

How to properly lay a waterproof membrane

The joints are welded with a building dryer and additionally filled with a special two-component adhesive. You should start from the very bottom edge, the width of the overlaps is at least 10 cm. To increase the strength of the fastening, each strip of the membrane is separately fixed with special fasteners, then the wide washers are closed.

Along the perimeter of the parapet, the membrane is also screwed with washers of large diameter, the distance between them is about 20–30 cm.

How to drain water from a roof

Experienced builders do not recommend trying to install external gutters and pipes on flat roofs to drain water to the ground. The best option is to run plastic pipes through the interior. The installation of the system should be done immediately after assembling the frame of the house; during the sheathing of the internal walls, the pipes are hidden. Due to such an installation location, the possibility of freezing is completely excluded, the reliability of the system is significantly increased.

The better to process OSB boards

There are many options, the effectiveness depends not only on the materials used, but also on the professionalism of the master. But practice shows that, under all equal conditions, bituminous mastics have the greatest reliability. Surfaces must be lubricated at least twice, this guarantees the tightness of the coating for a long period of time. Of course, the top membrane must also be of good quality and correctly installed.

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Flat roof houses - options and projects

Recently, there has been a growing interest in low-rise flat roof projects. Architects and developers are attracted by these unusual buildings, where you can equip an observation platform or even set up a real hanging garden. Of course, in practice everything is more complicated than in theory.

The design of a flat roof raises many questions regarding its cost, the choice of materials for insulation and waterproofing, the organization of water flow, maintenance and operation of the roof. Finding answers to them is not easy. The fact is that domestic contractors working in the field of cottage and summer cottage construction are well aware of the most popular design - pitched, and, as a rule, they do not have experience in erecting flat roofs arranged in a completely different way.

Which roof will be cheaper?

Immediately noteworthy is the fact that the area of ​​​​a flat roof is smaller than a pitched one, which means that fewer materials will be required, and the work will be cheaper. However, this statement is true only for regions with a warm climate and low snow load, moreover, if we are talking about an unexploited roof. In central Russia, to ensure the reliability and durability of a horizontal roof, rather expensive engineering solutions are required.

It turns out that 1 m 2 of a flat concrete or steel base, the bearing capacity of which will withstand the weight of the snow cover, costs 2-2.5 times more than the wooden beam structure of a pitched roof. The difference in the volumetric flow rate of the insulation is offset by the fact that a flat roof requires a more expensive high-density material. There is still hope to save on roofing, however, modern polymer membranes - optimal waterproofing for horizontal roofs - are no cheaper (and sometimes much more expensive) than flexible tiles.

You won’t need to install snow retainers, but you can’t do without a roof hatch and a drainage system. If you try to reduce the cost of the estimate, then later you will have to pay with the need to repair the roof every 10-15 years.

Finally, it should be noted that flat roofs are appropriate only on houses of modern architecture - with a large glazing area and sophisticated finishing with the latest facade materials. That and others won't be cheap.

Flat roof cover

As a rule, in low-rise housing construction, flat roofing is a prefabricated or monolithic reinforced concrete slab.

Reinforced concrete slabs (PB, hollow core PC, PV, etc.) are able to cover a span up to 9 m long and withstand a pressure of 8, 9 or 12.5 kPa (this value is indicated by the last digit in the product marking). They can serve as a "base" for any roofing pies, including those with a top layer of paving slabs or fertile soil. However, for the installation of the structure, it will be necessary to provide a check-in to the site of the truck crane (while steel beams and flooring are easy to lift with winches). The depth of support of the ceiling on the wall depends on the material of the latter - for example, for a 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 an elastic polymer tape. A monolithic w\6 floor is erected from heavy concrete using a removable (for example, from OSB boards on jack stands) or fixed (from corrugated board) formwork. It is reinforced with a two- or four-level welded frame made of bars with a diameter of 12 mm or more. The dimensions of a monolithic slab are not regulated (unlike a prefabricated one), which provides the architect with freedom in designing a building; other pluses are the absence of seams, the relative simplicity of the device of passage units (chimney, ventilation ducts) and high bearing capacity (subject to the technological regulations).

beam ceiling

In principle, when erecting a ceiling, a combination of beams (wooden, steel) and a supporting corrugated board can be used. However, experts do not recommend the use of wooden beams (with the exception of those made of LVL beams with a cross section of 200 * 100 mm) in regions where the snow cover pressure exceeds 1.2 kPa (about 120 kgf / m 2) - that is, in most of the territory of the Russian Federation. Roofing made of steel I-beams and corrugated board 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 withstands pressure of at least 6 kPa. But in general, it is less durable than concrete, and is relatively rarely used in individual construction. It is more reasonable to use corrugated board as a fixed formwork, which, by the way, does not eliminate the need to build a reinforcing cage.

Types of flat roof

In the low-rise sector, mostly non-attic flat roofs are in demand, because the attic requires additional costs and violates the architectural proportions of the house. So, the roof should protect from the winter cold and summer heat. At the same time, 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 the room is insulated 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.

There are special requirements for thermal insulation for a flat roof. The material must not only have a low coefficient of thermal conductivity, but also resist mechanical loads well - both distributed (pressure of the higher layers of the roofing cake, equipment, snow) and local ones that occur during installation. In addition, it is important that the material has hydrophobic properties and is non-combustible. At the moment, there are several ways to install thermal insulation: using mechanical fasteners, adhesive and free laying. In addition to the traditional two-layer insulation, one-layer laying is becoming an increasingly popular solution.

As for the options for the execution of the roof, there are dozens of them. Suffice it to say that only in SP 17.13330.2011 there are more than 40 "recipes". At the same time, manufacturers of coatings and insulation offer more and more new engineering solutions. However, they are always based on one of two fundamental schemes - traditional or inversion.

Traditional flat roof construction in general terms, it is as follows: a vapor barrier film (polypropylene, polyethylene, 6-tumno-polymer) is laid on top of the supporting base, then a heater follows, for example, mineral wool slabs with a compressive strength at ten percent deformation of at least 30 kPa, in one or two layers of total thickness from 200 mm. Above is a separating layer (for example, from a polyethylene film), along which a reinforced slope-forming screed is poured (a flat roof must be given a slope of 2-3% to the center or edges to ensure water flow). The dried screed serves as the basis for a rolled or mastic waterproofing coating.

Other options are also possible.

For example, a slope-forming screed can be placed at the very bottom of the pie; in this case, the roof waterproofing is fixed with gravel ballast, paving slabs on supports or special dowels. Some materials, for example, the RUF SLOPE system (Rockwool) or TechnoNIKOL Slant, allow you to do without a screed at all: the plates have a variable thickness, and with their help it is easy to create smooth level drops to ensure water flow.

Flat roofs are classified into unexploited and exploited. The former are visited only for revision, prevention and repair; for this purpose, a roof hatch is equipped, to which an attic staircase leads. The operated roof in cottages most often serves as a terrace, that is, a durable wear-resistant coating must be laid on it, and the supporting base is designed for increased loads. A variety of exploited - a roof with landscaping, lined with a turf layer on top of the main heat-hydro-insulating cake; usually it is arranged with paths and a recreation area. A convenient exit should be provided for the operated roof, for example, from a vestibule superstructure.

inverted roof it is arranged differently: in it, a heater 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 zone of positive temperatures (freeze-thaw cycles are destructive for almost any material). It is easy to turn an inverted roof into an exploitable one, for example, by filling the insulation with a drainage layer of sand gravel and laying paving slabs. The disadvantages of the design include a more complex drainage system. However, drains need to be discussed separately.

For exploited roofs, as well as roofs arranged 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 extremes and UV radiation, which significantly extends the 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 errors during the deposition of the material. One layer is enough for a polymer membrane, and automatic welding equipment ensures reliability, which greatly increases the speed of work. In addition, an open flame is not used when installing a polymer membrane, so the technology is considered safer.

Coil materials based on modified bitumen, as a rule, are fused with a gas burner (a), while it is difficult to prevent small flaws that can cause leakage (if there is no second layer). The quality of welding of PVC coating strips (6) is much easier to control

Drainage and water protection system of a flat roof

A flat roof is equipped with a parapet (attic) 30-90 cm high, which helps to ensure organized water drainage; on the operated roof, it also serves as a safety fence. At the same time, the design of gutters should be approached very responsibly, because in the event of an error, a huge puddle can form above your head, which threatens to leak and damage the 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 therefore more durable and reliable than the outdoor one. Let's talk more about its main elements. Drainage funnels are installed on low sections of the roof. As a rule, two funnels are mounted on roofs up to 150 m 2 - the main one, connected to the riser, and the emergency one, with water discharge 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.

Flat roofs are in demand in modular construction. Among the advantages of this method are the affordable cost and high speed of construction of housing, as well as the possibility of a phased increase in its area.

For inverted 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.

In systems of a new type, the so-called siphon-vacuum systems, 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 gravitational ones.

The drain riser is made of sewer pipes - polypropylene, PVC, and it makes sense to use noise-absorbing products, such as RAUPIANO Plus (REHAU), or to soundproof the riser, otherwise you will hear the murmur of water for hours. The riser is attached to the funnel using an elastic coupling. When laying pipes, minimize the number of elbows and the length of horizontal sections that reduce the throughput of the system. A drainage pipe laid in the basement or insulated underground connects the riser to the rain sewer or provides water discharge into the 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 revision module.

When choosing the standard size of elements of a traditional gravity system, they proceed from the intensity of rains 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 branch pipes embedded in the parapet, under which classic funnels are installed (as on a pitched roof) and downpipes attached to the walls with brackets. When calculating, it is assumed that for every square meter of roof area there should be 1-1.5 cm of the cross section of drainpipes. Elements of the external system can be made of PVC, steel, copper, zinc-titanium.

flat roof landscaping

Turf-covered roofs have been used since ancient times in countries with a moderately cold and humid climate, 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 covering it from ultraviolet rays. In addition, it absorbs rainwater, unloading gutters, dampens the sound of rain, protects the upper 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 an increase in the load on the supporting structures of the building and an increase in the cost of construction.

In addition, the green carpet needs care, the intensity of which depends on the selected plant species. If you do not pay due attention to plantings, they will freeze and die from drought.

For landscaping the roof, it is necessary to lay on top of the main waterproofing layer (in the case of an inversion scheme - on top of the insulation) an additional cake of materials that will protect the waterproofing layer from roots, filter and drain rainwater. For these purposes, special films, dense geotextiles, gravel bedding or drainage-moisture-accumulating membranes made of high-density polyethylene, such as PLANTER GEO or Delta-Floraxx, are used.

Then a mixture of minerals and fertilizers is poured - the so-called soil substrate. It can be prepared independently by adding fine expanded clay (5-15%), sand (about 20 96) and fertilizers to a light soil mixture from neutral peat. As for plants, it is easiest to limit yourself to meadow forbs and drought-resistant ground covers - sedum, carnation-herbal, thyme.

For them, it is not necessary 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 on the roof among ornamental shrubs, you will have to provide watering and increase the thickness of the soil to 20-40 cm. Such a roof is called intensive, it creates a significant additional load on the floor, so it should be provided at the design stage of the building.

What is the best coating for a flat roof

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

ROLL REINFORCED POLYMERIC-BITUMEN ROOFING.

The mechanical strength of these materials is several times higher than that of roofing paper (roofing felt, roofing felt). And modifying additives increase resistance to moisture, air and ultraviolet. The material is glued to the base with mastic, fixed mechanically or (most often) welded. There are coatings for the lower layers of the roof ("Technoelast EPP", "Uniflex EPP", "Bireplast TPP", etc.) and for the upper ones ("Technoelast EKP", "Uniflex EKP", "Hydrostekloizol 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 m 2 and the average service life of a roofing carpet is 15-30 years.

ROLL 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 m 2. It is important to consider that this material does not tolerate contact with bitumen.

ROOF COVERING OPTIONS

Traditional with external drain
1 - overlap; 2 - slope-forming screed; 3 - vapor barrier; D, 5 - mineral wool insulation; 6 - waterproofing; 7 - drain
inversion
with internal drainage
1 - coupler; 2 - PVC membrane; 3 - EPPS; 4 - funnel with a drainage ring; 5 - drainage membrane; 6 - sand; 7 - paving slabs