Attic flat roof. How to build a flat roof: installation technology and recommendations. Traditional or inversion roofing

The choice of one design or another largely determines the possibility of using the attic as an additional living space, resolves the issue of the need for insulation and determines the type of roofing covering.

A flat roof is a specific option that does not allow the attic to be equipped as a living space (due to its absence).

But it offers a lot of possibilities for using the territory as an auxiliary site, a place for placing equipment or as a private recreation area, separate from the external space.

A flat roof can provide many interesting possibilities in this regard, but there are limitations to its use.

The main feature of a flat roof is its almost horizontal surface. such surfaces are low - up to 8 degrees, it is needed only for drainage of rain or melt water.

According to the conditions of the plane's location, there is practically zero wind load (if properly constructed without overhanging edges) with a maximum snow load.

Wherein, the roof structure has a complex multi-layer structure, ensuring the tightness of the coating and the working condition of the insulation.

The most favorable operating conditions for flat roofs:

• Small amounts of snow in winter. It is most suitable for use in regions with warm or little snowy winters, when removing snow from the roof does not cause difficulties.
• Wind force does not have a significant effect on the roof, therefore, the construction of such roofs in areas with strong or gusty winds is permissible.

For areas with cold and snowy winters, the use of flat roofs is only recommended for small commercial buildings having a relatively small area.

The use of flat roofs on residential buildings is more common in southern regions, where there is no problem with high snow pressure in winter.

Flat roof

The structure of the roofing pie

There is no specific, classic composition of the roofing pie of a flat roof. Layer structure most often based on the following factors:

• Roof purpose;
• Floor type;
• Roofing material.

The decisive factor that determines the composition of the roof from the very beginning of construction is the purpose of the roof. It determines what material is needed for the construction of the floor, how exactly it will be insulated, and what is the optimal coating material in this case.

Insulation of a flat roof made of soft roofing is done from the outside, since this method is much more convenient and reliable in terms of the tightness of the cake.

The general insulation technology looks like this:

• Base (concrete, wooden floor);
• Vapor barrier film;
• A layer of insulation;
• Top layer of waterproofing;
• Roofing.

This is the general plan, in practice it is often supplemented or complicated for the purpose of more reliable protection against water penetration or the formation of cold bridges.

Roofing pie

One of the options for installing a flat roof is inversion roofing. This is a relatively new type of pie design that takes into account the disadvantages of conventional options.

The fact is that a common problem with flat roofs is water seeping through the insulation into the ceiling and the appearance of stains and streaks.

To eliminate this phenomenon, inversion roofing is used when A reliable waterproofing carpet (often multi-layered) is installed between the ceiling and the insulation..

The composition of the pie is built as follows:

• Overlap;
• The waterproofing preparation layer is usually a construction primer;
• Waterproofing carpet;
• Geotextile layer;
• Insulation (optimally extruded polystyrene foam);
• Top layer of geotextile;
• Ballast fill layer of gravel.

If necessary, a rigid covering can be laid on top of the ballast layer to maintain uniform ballast thickness and ease of movement.

Inversion roofing cake

Is the roof based on wood or concrete?

Wood or concrete can be used as a base for a flat roof. Both options are acceptable, but not interchangeable.

So, wooden base is used for small buildings, most often for economic purposes.

If there is no heating, then such a roof is not insulated, a simple rafter system is made and the roofing covering is laid on top. However, wooden floors are also used for residential buildings.

This is due to the desire to lighten the roof and remove excess load from the walls (for example, with the frame construction method).

CAREFULLY!

This option imposes certain restrictions on the functionality of the roof, excluding the presence of heavy equipment, a large number of people, etc. on it.

More often, for the roofs of residential buildings used, a concrete slab is used as a base. This overlap has a number of significant advantages:

• Reliability;
• No noticeable deformation from loads;
• Penetration of moisture into the material will not cause rotting;
• Finishing a concrete floor is easier than finishing a wooden one.

Since it is produced outside, the lower surface of the concrete floor (the ceiling of the upper floor) will be open, which allows you to use any available type of finishing - from simple painting to installing a stretch ceiling.

If the ceiling is made of wood (beams), then the finishing should be done taking into account possible deformation - “sagging” of the ceiling due to existing loads.

Sectional photo of the roof basics:

Wooden base

Concrete base

Flat roofs: arrangement of private houses

The composition of the roofing cake is never chosen at random. The main selection criterion is the general purpose of the roof:

• Lightweight. The roof serves only as protection from precipitation. Mainly used for auxiliary buildings for utility purposes;
• Exploited. Such a roof serves as a platform for placing various equipment, for creating recreation areas, small greenhouses, swimming pools, etc.;
• Green. On such a roof there is a lawn with grass, plants, etc. Serves as a mini-square for relaxation.

Depending on the purpose of the roof, the type of flooring is selected, which, in turn, largely determines the optimal type of roofing material. Therefore, the composition of the roofing cake may have its own individual characteristics.

So, for a flat roof of an outbuilding it will be enough:

• Rafters;
• Lathing;
• Roofing covering (metal profile, etc.).

Lightweight roof

For a used roof, which is used as a site for installing solar panels, satellite television dishes or other equipment, the composition is much more complex:

• Concrete floor slab;
• Cement screed that forms a slope for water drainage;
• Waterproofing layer;
• Drainage material that removes water from under the upper layers;
• Insulation layer;
• Geotextile layer;
• Sand preparation layer;
• Paving slabs.

In this case, the outer covering is paving slabs, as a durable and cheap material.

ATTENTION!

At the same time, rain or melt water can quite easily penetrate the insulation layer, so it must be resistant to moisture, impermeable to water, or, as an option, painlessly pass water through the drainage layer to the drain.

Operable roof

Pie diagram for creating a green roof:

• Concrete floor slab;
• Layer ;
• Multi-layer waterproofing carpet;
• Insulation;
• . It consists of a separating layer of reinforced screed, a double layer of technoplast (EPP and Green), and a geodrainage roll layer;
• Layer of soil with plantings.

In this case, there is a multi-stage waterproofing system that reliably cuts off the insulation material from the top soil layer. This cutoff, at first glance, is too complicated, necessary to guarantee the creation of a reliable barrier to water.

The soil is an active accumulator of moisture, which will certainly seep into the lower layers, so the complexity of the composition of the pie is fully justified.

Green roof

How to cover a flat roof

The material for covering a flat roof is selected based on its purpose.

Unused surfaces are most often covered with roofing felt and the joints are sealed with liquid bitumen.

Recently, a large number of similar materials have appeared with improved characteristics that make it possible to more reliably protect the roofing pie.

Operated surfaces require a tougher and more durable coating. At the same time, the task of hermetically sealing the insulation from external influences is not removed, so most often a sand-cement cushion and a working layer - paving slabs - are laid on top of the soft roof.

Coating

Installation of a used flat roof

How to make a flat roof? First of all, you need to decide on the basic parameters - roof type, structure, etc. Let's consider the option of installing a serviceable flat roof with a concrete floor and external drainage using gutters:

1. The surface of the floor is covered with a layer of slope-forming concrete screed (slope). To save concrete, a layer of gravel is first poured on a slope, after which a screed is laid on top. Since this stage refers to “wet” work, then It is recommended to cover the surface of the ceiling with a layer of primer or similar material.
2. Laying vapor-waterproofing. As a material, you can use various fused films or roll membranes. Laying with overlap, seal the joints with tape.
3. Insulation layer. Either stone mineral wool or extruded polystyrene foam is used. The insulation is laid in several layers, minimum 2 layers. This requirement is caused by the need to prevent the penetration of cold through cracks in the joints of the insulation.
4. On top of the insulating layer a layer of waterproofing is laid.
5. Filling the ballast layer - gravel, sand, etc.. The role of this layer is double: protecting the film coating and draining water coming from melting snow or precipitation in the summer.
6. On top of the ballast layer if necessary, a layer of paving slabs can be laid for ease of walking on the surface. In this case, you will need an additional sandy preparatory layer, a direct substrate for the tiles.

The indicated sequence is one of the options; there are many similar methods that are equivalent in results, but differ in details.

The installation of a flat roof, traditionally considered an accessory of auxiliary buildings, can be carried out in such a way that the roof surface turns into an additional platform that can be used for various needs.

Depending on the climatic conditions of the area, the surface of a flat roof is turned into a green lawn, a technical area for placing equipment, or a recreation area.

All roofing options require careful arrangement and expensive materials. The quality of the result directly depends on the qualifications of the people performing the work and on the financial capabilities of the home owner.

But don't forget that you can build a flat roof with your own hands.

Investments in an equipped, usable flat roof will only be worthwhile in regions with short, mild winters and low average monthly precipitation. All other issues can be resolved and do not cause serious problems.

Waterproofing

Insulation

Useful video

In this video you will learn what the structure of a flat roof made of fused materials is:

In contact with

Flat roofs, their types and designs can be classified:

• According to the purpose of the surface. Can be exploited or unexploited.
• According to the method of laying the roofing pie. It can be traditional and inversion.
• By type of construction. It can be attic or non-attic.
• Ventilated and non-ventilated structures are distinguished separately.

Operable roof

A usable flat roof can be used as a parking lot, helipad, tennis court, swimming pool, green roof or just a terrace. In any case, it is necessary to calculate the possible load on the roof.

• Load from operation (weight of a person, car, water in a swimming pool, etc.).

In some cases, the roof is subjected to a pressure of 20 tons per square meter.

Also, due to the design of a flat roof, it is highly susceptible to ultraviolet rays.

Together, these factors mean that the choice of building materials for such a roof must be approached with particular care.

The structure of the roofing pie of the roof in use is as follows:

• Reinforced concrete floor slab.
• Sloping layer. It is made of slag, concrete, expanded clay, wedge-shaped mineral insulation and other similar materials. The top is secured with a concrete screed. Slope angle up to 3%. Necessary for high-quality drainage of water in the required direction. Sloping is always installed in front of the waterproofing to ensure water flow through it.
• Leveling concrete screed.
• Waterproofing. Made from bitumen, polymer, PVC materials and sealants. Roofing felt is often used, laid in two layers, and it is important that the joints of the upper and lower rows do not coincide.
• Thermal insulation. Keeps the room warm in winter and cool in summer. Requires a careful approach to calculating thickness. In case of an error, condensation may form inside the room. If not an inversion type of roofing is used, but a traditional one, the insulation must be resistant to steam. If on the contrary, there must be resistance to water absorption.
• Drainage layer. Given the flat roof technology, water should flow along the surface into drainage trays. But in other cases, moisture can get into the joints between tiles used as finishing paving elements, or be absorbed into the ground when using a green roof. To prevent the elements of the roofing pie from getting wet, a drainage layer is installed that drains water in the right direction.
• Then everything depends on the type of roof being used. If it is a green roof, geotextiles are laid, which will prevent plant roots from destroying the roofing pie. If it is a roof terrace, or a parking lot, behind the drainage layer there is a concrete screed under the tiles or other finishing material.

Please note that when using traditional roofing, the order of the elements of the roofing pie changes. A vapor barrier is laid over the slope-forming layer, then insulation, and only then waterproofing.

The advantages and disadvantages of this method are discussed below.

Unused roof

An unused flat roof is distinguished by its efficiency. It is not designed to withstand any loads other than snow. This allows for a less careful approach to the selection of building materials.

The structure of a roofing pie of this type of roof is as follows:

• Reinforced concrete floor slab. Instead, it is allowed to use profiled sheets with a high wave height, such as N-153 and N-158.
• Slope formation layer.
• Vapor barrier.
• Thermal insulation.
• Waterproofing.
• Ballast layer of gravel. The thickness of such a layer should be from 10 to 20 centimeters. Necessary to protect waterproofing from exposure to ultraviolet rays and prevent fires.

Once again, we draw your attention to the fact that the layers of steam, heat and waterproofing can change places depending on the type of roof used.

Traditional roof

The traditional type of flat roofing has been used for a very long time. In this case, the roofing pie will look like this:

• Slope formation layer.
• Vapor barrier. Necessary to protect the insulation from steam emanating from the room. Otherwise, even in the case of one percent moistening of the thermal insulation layer, a significant increase in thermal conductivity occurs. Made from specialized vapor barrier membranes and films.
• Thermal insulation. Almost all types of insulation can be used, even with a low percentage of moisture resistance.
• Next, according to the traditional roofing drawing of a flat roof, a layer of waterproofing should be laid. Please note that it must be of high quality, since it is absolutely not protected from temperature changes.

The advantages of a traditional roof are that it guarantees protection of the thermal insulation layer from getting wet. Firstly, this allows you to use the entire range of roof insulation materials. Secondly, the insulation will not lose its thermal conductivity characteristics, which means that a comfortable temperature regime will always be maintained in the room.

At the same time, this flat roof design compromises waterproofing. It is maximally susceptible to temperature changes, which leads to its accelerated aging. Also, the insulation does not protect the waterproofing from external force loads, which again negatively affects its service life. In general, this type of roofing is less durable and requires fairly frequent repair work.

Inversion roof

It is a more progressive type of flat roof device. It assumes the installation of the following roofing pie:

• Reinforced concrete floor slab or corrugated sheet.
• Slope formation layer.
• Leveling concrete screed.
• Primer for waterproofing, for better adhesion. During this process, the screed is carefully inspected for cracks and water bubbles. The cracks are covered with solution, water bubbles are removed.
• Waterproofing.
• Thermal insulation.
• Next is either a drainage or ballast layer, depending on whether the roof will be used or not.

Inversion roofing has the following advantages:

• Protection of waterproofing film from temperature changes. As a result, this extends the service life of the film in particular, and the service life of the roof in general.
• The insulation redistributes force loads across the waterproofing in such a way that this does not affect it.
• Extruded polystyrene foam, which is usually used as thermal insulation for this type of roofing, is cheaper than mineral wool used for traditional roofing.
• The inversion design of a flat roof allows for more repairs, if it is necessary to replace or add insulation.

There are also disadvantages, which include:

• It is permissible to use insulation materials only with closed cells to prevent them from getting excessively wet.
• The need to install a more complex design of gutters.

Attic roof

The technology of installing a flat roof with an attic implies the possibility of using two types:

1. The attic roof is a lightweight superstructure, and the attic floor serves as the main supporting structure.
2. The attic floor and the attic roof are independent of each other and are able to withstand force loads equally well.

The advantages of a roof with an attic are:

• Possibility of constant monitoring of the tightness of the waterproofing layer.
• The ability to regularly monitor the condition of the insulation.
• The insulation can be laid after the roof has been installed.
• The attic itself performs thermal insulation functions.

The disadvantages include:

• Impossibility of mechanical snow removal, provided that the attic roof is used as a light superstructure. Instead, the attic is blown with hot, dry air, which ensures that the snow from above melts and gradually melts away.
• This type of roof is more expensive.

Roofless roof

More popular is the roofless roof. She:

• It costs less than an attic.
• Easier to install.
• Provides snow melting by conducting heat from the room.

A roofless flat roof also has a significant disadvantage:

• There is no way to timely detect a violation of the waterproofing layer. This damage appears as a wet spot on the ceiling, making it impossible to determine the exact location of the leak.

Ventilated and non-ventilated roof

Roof ventilation is arranged between the insulation and the waterproofing layer. Thus, constant air circulation is achieved, which ensures constant dryness of the insulation. Used with the traditional type of roofing pie.

When installing ventilation, it is important to adhere to the following recommendations:

• The height of the ventilation opening is at least 1/30 of the width of the building.
• The diameter of the hole is at least 1/150 of the total roof area.
• Air inlets should be lower than the outlets.
• The holes are evenly distributed across the width of the entire building.

In turn, non-ventilated roofing does not require the creation of additional roof elements for flat roofs. But this somewhat shortens the service life of the thermal insulation material.

The apparent simplicity of a flat roof often misleads novice home builders. The elementary configuration gives rise to thoughts about the efficiency and low cost of construction. The minimum number of structural elements can dull the vigilance of independent performers who are ignorant of the intricacies of the roofing business.

In reality, installing a flat roof requires scrupulous adherence to the rules unique to it, guaranteeing the flawless operation of the structure and long-term operation.

Flat roofs are a separate category of roofing structures that do not require the construction of a rafter frame. Purely visually, it is a ceiling that rests directly on the walls of the building. Due to the absence of slopes, a flat roof does not upset the windage that occurs under the influence of gusty winds. However, its configuration does not contribute to the rapid removal of snow deposits from the surface.

The load from the snow is not transferred to the rafters, as in standard pitched systems, but presses directly on the walls of the building. Therefore, it is strongly recommended to equip houses with flat roofs in regions with insignificant amounts of winter precipitation and high wind loads.

In regions and regions of the country located in the middle zone and to the north, flat roofs are used mainly in industrial construction.

Private owners install them over one-story extensions, garages, and household buildings. For an independent craftsman, a flat roof over a shed or shed is an excellent option to practice as a roofer.

Briefly about the design of a flat roof

It is customary to call roofs flat, the only conventional slope of which is located to the horizon at an angle from 0º to 1.5º, or otherwise up to 2.5%. However, a number of technical sources call systems with a slope of up to 5º flat, a percentage value of up to 8.7%.

Even roof structures have a slight slope, creating a clearly horizontal impression. It is formed to drain wastewater to drainage points or to an overhang.

Regardless of the steepness, the layers of a flat roof are arranged in a strictly defined order:

• Vapor barrier covering the base. It is necessary to protect the insulation from the penetration of household fumes.
• Insulation laid in one or two tiers. Required to prevent leakage of heat waves through the upper ceiling, used exclusively in insulated systems.
• A screed created when the thermal insulation is insufficiently rigid or when there are no slopes for drainage.
• Waterproofing that protects the insulation and ceiling from the destructive effects of atmospheric water. It is laid with a continuous waterproofing carpet.
• A finishing coating that gives the structure an aesthetic appearance.

The brands of waterproofing materials currently supplied to the market successfully perform the functions of finishing roofing. These include numerous rolled and mastic bitumen, bitumen-polymer, and polymer varieties. Most of them are laid in one layer.

Due to the slight slope of flat roofs, the use of piece materials in construction is contraindicated, because multiple joints between elements create the risk of leaks.

It is undesirable to use large sheet metal due to the harmful effects on the material of water stagnating on a flat surface during periods of heavy rain and snowmelt.

When using old, well-known roofing felt types of roll coverings, the finishing roof is arranged in 4 or more layers, the lower of which play the role of waterproofing. A mastic or emulsion self-leveling roof is constructed in a similar way: the emulsion or mastic is applied in five or more layers, alternating pasty or creamy material with layers of fiberglass or polyester.

To lay and fix the above elements of the roofing pie of a flat roof, a rafter structure is not required. They are laid directly on the base, which can be a ceiling, a screed created on top of it, or the upper plane of the attic structure. To fasten PVC-coated systems, use adhesive, mechanical or. Self-leveling roofs are applied according to their name, the descendants of roofing material are fused or glued.

Unlike their pitched counterparts, flat systems do not have sheathing that creates ventilation channels for washing the insulation with air currents. Therefore, the selection of design solutions, materials and their sealed installation should be approached with due respect and focused attention.

A ventilated flat roof is only possible when lumber is used in the construction of the ceiling and attic. The latter option is most often used in private construction.

Types of floors used

The construction of flat roofs is carried out on floors made of reinforced concrete, wood and profiled sheets. The choice of material for the ceiling depends on the purpose of the roof structure, the size of the span to be covered, possible operation and ease of maintenance.

One of the significant advantages of a flat roof is the possibility of organizing a used area on it: a place for relaxation, a solarium, a green area, a terrace, etc. Of course, the overlap for such objects should be quite powerful. In addition, in the flat family there are roofs that do not involve incidental use, and therefore do not require a thorough covering.

Depending on the operational criteria, flat roofs are equipped with:

• Reinforced concrete floors, if it is planned to organize useful space above a long-span brick or concrete box.
• Steel profiled flooring on metal beams, if an unused roof is being constructed that covers spans of any size between walls made of brick or other artificial stone.
• Wood panel made from boards 40-50mm thick, up to 180mm wide. It is used to cover medium and large spans of wooden buildings in the event of planned operation.
• Particle boards and fibreboards on wooden beams, used to cover small spans of wooden and stone buildings. They are used if an unused roof is being constructed.

Lumber is a leader in the construction of low-rise residential buildings, because... are ahead of concrete and steel competitors in terms of environmental criteria.

Note that wood is inferior in fire resistance. True, fire hazard in low-rise housing construction is not recognized as a decisive factor. In addition, there are effective means to combat it - fire retardants.

Rolled coverings in flat systems with a wooden base then serve only as waterproofing, on top of which plank or parquet flooring is installed.

If a flat roof is being erected over a brick or concrete box, it is wiser to lay a reinforced concrete floor for an object in use or a corrugated sheet for an object that is not in use.

The overlap of a flat roof does not always serve as the basis for its installation. In some cases, an attic structure is erected above the ceiling, which can be either a canopy over the base with a roofing pie, or the base itself.

Roofing pie structure attic roofs are similar, but the layers can be located at different levels.

With or without an attic?

The unconditional inclusion of flat roofs in the category of non-attic structures is fundamentally incorrect, although it has strong technical justifications. They may or may not have attics, although they are not formed by installing rafter legs.

Depending on the presence of an attic, flat roofing systems are divided into:

• Without roofs, the elements of which are structurally combined with the ceiling. They are completely devoid of an attic superstructure, which significantly reduces the budget allocated for their construction.
• Attics with an attic superstructure above the ceiling. The minimum height of the superstructure is 80cm. The construction of attic structures for flat roofs is more expensive, but by separating the floor from the roof, the service life of the system increases at least three times.

In addition to the budget cost, one of the advantages of atticless systems is the ability to eliminate mechanical cleaning. The snow will melt due to the heat emanating from the room. Due to spontaneous precipitation, it is not advisable to equip flat roofs without an attic with parapets.

It is enough to install railings, which further reduces costs. The disadvantage of the absence of an attic will affect when identifying the causes of leaks, because the condition of the thermal insulation and other layers of the cake cannot be controlled.

The attic is an air chamber between the ceiling and the roof. This is a kind of buffer that compensates for the difference in temperatures outside and inside the premises.

The presence of an attic reduces the likelihood of condensation formation, and as a result extends the life cycle of structural elements. Elements of the attic system are always available for observation: the simplicity of inspections is difficult to overestimate.

An undeniable advantage is the possibility of installing insulation after construction, which prevents it from getting wet. The disadvantage of flat roofs with attics is their high cost and the need to regularly clear snow.

Despite the mythical cheapness of atticless systems, this is a very complex structure that requires experience from the builder, careful selection of materials and adherence to technologies for their hermetic connection. It is better for an independent craftsman to give preference to roofs with an attic, if their construction is not excluded by the design decision.

Subtleties of water drainage

Flat roofs are required to be equipped with drainage systems, which are required to freely drain water at an operational pace all year round. Systems come in external and internal types.

The optimal type of drainage system is determined by the climatic conditions of the construction area:

• External gutters constructed when installing flat roofs in southern regions, where icing of drains in external pipes is excluded. According to the external type, water is discharged to pipes located outside along the perimeter of the building or to a gutter attached along the lowest overhang. In the middle zone, only flat roofs of non-residential buildings are equipped with external systems.
• Internal drainage systems atmospheric water when installing flat roofs are built in the middle zone and to the north. In accordance with the internal design, water is transported through slopes or inclined pipes to water intake points in the center of the roofs. Drainpipes transporting water to the sewer system are laid inside the building, but isolated from the premises.

Despite the impressive cost, the construction of an internal drainage is mandatory for temperate and northern latitudes, and in the south its construction is irrational.

Installation of slopes for drainage

If the slope of the flat roof was not provided for during the construction of the old roof and the construction of the new one, it must be created. The roof must be inclined towards the water intake funnels by at least 1-2%, approximately 1º.

Those who want to know how to correctly make a slope on a flat roof and what material is best to use to form slopes should adhere to the following recommendations:

• Slopes on reinforced concrete slabs are made mainly using a screed, or a screed is combined with preliminary filling of expanded clay or laying slab insulation. On an unused roof, it is enough to lay wedge-shaped mineral wool slabs, produced specifically for forming slopes.
• Slopes on corrugated floorings are formed using metal structures or wedge-shaped insulation.
• Slopes on wooden bases are specified constructively, but if they are not included in the project, it is possible to use wedge-shaped mineral wool.

Due to their serious weight, screeds are poured only for exploited roofs erected over a concrete floor. On a concrete slope, the recommended thickness of the screed is 10-15mm, on rigid insulation panels 15-25mm. For backfill thermal insulation, the screed is poured with a layer of 25-40 mm and a metal mesh is used for reinforcement.

Nuances of organizing ventilation

Normal ventilation can be done using the only method - by installing battens on the floor beams, similar methods are dictated to us. It is clear that this method is valid only for wooden options, and for roofs on a concrete base or corrugated sheet it is unacceptable.

The ventilation system for roofing pies on concrete and corrugated sheets depends on the type and characteristics of the finishing coating. PVC roofing is capable of spontaneously transmitting excess moisture from the insulation to the outside, so there is no need to install ventilation ducts between it and the insulation.

When using bitumen and bitumen-polymer materials, it is mandatory to install weather vanes over the entire area of ​​the flat roof. The spacing of these devices depends on the thickness of the insulation. Vane aerators ensure the removal of moisture from the under-roof space to the outside.

Algorithm for constructing a flat roof

Let's consider the common case of constructing an unused flat roof over an extension on a suburban site. It will be equipped with an external drain. Insulation of the structure is not expected, because climatic conditions and the purpose of the room below do not require thermal insulation.

The sequence of constructing a cold flat roof on wooden beams:

• We mark the installation step of the floor beams, for which we will use a board 40-50mm thick. Installation step from 50 to 70cm: choose it based on the actual length of the walls. There should be equal spaces between the beams.
• We place the board on its edge, fasten it with nails or corners. The required slope to the lowest overhang is created spontaneously due to the difference in the height of the box walls.
• We lay a continuous flooring made of OSB boards, moisture-resistant plywood or other similar material on the beams. There should be a gap of 3-5mm between the plates to compensate for thermal expansion. They are fastened with galvanized self-tapping screws or rough nails.
• We install a wind board along the perimeter of the roof, the edge of which rises 5-7 cm above the plane of the future roof so that a small side is formed.
• We nail a wooden strip with a triangular cross-section or a regular plinth to the sides. These are fillets necessary to drain water from the edges of the roof.
• We treat all wooden elements with antiseptics and fire retardants. After they dry, apply primer.
• We lay an additional waterproofing carpet in a strip along the perimeter on top of the fillets. In the case of junctions and pipes passing through the roof, additional waterproofing is applied to the adjacent vertical planes in the same way, i.e. on top of the fillets.
• We fuse the finishing roofing material selected for installation, heating its back side with a gas burner.

In the case of thermal insulation, a vapor barrier layer is first laid out on the base, the edges of which are placed on the vertical sides. Insulation boards are placed in a kind of pallet formed by the vapor barrier, the thickness of which is calculated according to the requirements of SNiP 02/23/2003. Thermal insulation is attached to the base with self-tapping screws and telescopic devices.

Then waterproofing is laid over the sides and junctions. If one of the latest brands of rolled waterproofing material is chosen for the installation, then it will also be entrusted with the responsibility of the finishing coating.

An impressive range of new polymer-bitumen and polymer coatings are laid in one layer, which helps to save the paver's effort and construction costs. Among them there are materials that are extremely preferable for home craftsmen and do not require the use of a gas burner. They are glued to mastics or using the back adhesive side, fixed mechanically, laid loosely and loaded with ballast.

Video for DIYers

This video collection will help you reinforce information about the difficult task of constructing flat roofs:

We hope that the information we presented will help future roofers who decide to practice with their own hands in constructing a not-so-simple design.

There are many conditions for the proper construction of a flat roof, but they must be observed for ideal operation and long service. Information about the intricacies and specifics of constructing a flat roof will help not only determined craftsmen, but also owners of country estates who resort to the services of third-party construction organizations.

This option for arranging the upper part of a building is used, as a rule, in the construction of “high-rise buildings”, as well as various administrative, industrial, warehouse and some other buildings: pavilions, showrooms and the like. Despite the fact that a flat roof has a number of disadvantages, this does not reduce the popularity of such a design, including in private housing construction.

Advantages of flat roofs

Firstly, the installation of a flat roof can be carried out independently, rather than inviting assistants or hiring professionals, as, for example, when constructing a roof with a complex configuration (hipped, etc.). Consequently, you will not have to pay for their work (we are not talking about large areas where it would be problematic to cope alone).

Secondly, the construction of such a roof provides significant savings both in materials (money) and in time (the covering area is much smaller than with a pitched roof). You won’t have to make numerous calculations or order a project (which won’t be cheap), assemble a complex system of rafters, install jibs, extensions, and so on. In addition, there are no restrictions on the choice of type of roofing.

Third, a flat surface is much easier to maintain and repair, which also provides significant savings in the long term.

Fourth, the ability to choose arrangement options. A flat roof can either serve only as a traditional “cover” for a house, or be used (inverted). For example, greenhouses, summer gardens, solariums and the like are mounted on it. Even helipads are being built. This fully compensates for the inconvenience due to the lack of attic space.

Flaws

• Increased requirements for waterproofing. Since the roof is located horizontally, water falling in the form of precipitation will stagnate on it. You can use , for example.
• Debris will constantly accumulate (for example, fallen leaves), so such a roof will have to be serviced more often.
• Lack of attic (attic) space

What to consider

• The maximum load that the roof will experience (for a rafter structure). This means the weight of the frame itself, roofing material, layers of insulation and insulation, as well as possible snow cover. In addition, you need to count on the fact that the roof must withstand the weight of people who will subsequently walk on it.
• The purpose of the building and the possibility of further use of the surface (for example, equipping a terrace). Depending on this, the type of overlap is determined.

Work technology

The simplest version of a flat roof is when reinforced concrete slabs are laid (for example, a garage, shed). Everything here is extremely simple. A so-called “layer cake” is placed on the surface: a vapor barrier, if necessary, insulating material, a layer of waterproofing. For the equipment of the latter, roll materials are most often used.

Insulation of a reinforced concrete slab can be done by pouring a layer of expanded clay and placing a cement screed on top. Slag and some other materials are also used.

Traditionally, roofing felt is used for waterproofing, which is covered with bitumen mastics on top. It is necessary to take into account that this material will last no more than 5 years, and then you will have to do repairs. It is more expedient to lay polymer materials, for example, membranes, as a “waterproofing agent”. Liquid rubber is also great.

Since the installation of slabs requires the use of special equipment, when installing a flat roof yourself, you can equip a simple rafter system made of wood.

First of all, supports - Mauerlats - are laid on the upper parts of the load-bearing walls. The most commonly used material is timber. It must be taken into account that these structural elements must be rigidly fixed to prevent the possibility of their horizontal displacement.

Therefore, metal pins are first embedded along the entire length of the walls into their upper end surfaces. Their length is calculated so that after installing the mauerlats they rise above the beam by about 5 cm. Threads must be cut at their ends.

If the masonry is old, then a “ribbon” of concrete mortar is placed on top of the walls. After this, pre-designated holes with a diameter slightly larger than the cross-section of the metal “fingers” are drilled in each wooden blank. First, strips of roofing felt (or similar waterproofing material) are laid on the tape, and then Mauerlats. They are mounted on pins, and a washer is put on top of each and with the help of a nut the beam is securely fixed at the installation site.

Next, the floor beams are laid. It is necessary to take into account that the roof should protrude beyond the dimensions of the house by 50 - 60 cm (the required overhang). This will protect both the walls and the blind area from water flowing from it, as well as from raindrops.
Construction of a supporting frame. Depending on the type, it can be either solid (boards, slabs) or cellular (lathing).

• Vapor barrier.

• Insulation. For flat roofs there is a nuance. The absence of an attic space deprives such a building of an “air cushion” from above. Therefore, insulation is carried out both outside and inside. But at the same time, you need to take into account the weight of such material, since it is an additional load on the rafter system.

• Waterproofing.

• Roofing covering.

• Finishing of overhangs.

This is only a general list of necessary activities. The technology for performing work on each item depends on both local conditions and the selected materials.

• Any “wood” used in construction must be well dried. The moisture in its structure gradually “leaves” (natural shrinkage of the material), which leads to a change not only in the volume of the workpiece, but also in its deformation (for example, twisting).
• Wood has two significant drawbacks: it burns and is susceptible to rotting. Therefore, before using it, all wooden parts of the structure are pre-treated with fire retardants and antiseptics. It is better to spend money on these products than to suffer from frequent repairs later.
• When installing mauerlats, you need to constantly monitor their horizontalness using a building level. Otherwise, the roof will be skewed. If necessary, either the tape is leveled or a rigid lining is made under the Mauerlat.
• To prevent stagnation of water on the roof, it is advisable to make it with a certain slope (approximately 3 0 - 5 0). As a rule, the decline goes towards the rear side of the building. To do this, the height of the front mauerlats increases, so the floor beams will lie with a slope.