Flat roof for a private house: is it worth it or not? Flat roofs, their types and designs Complex round flat roof

For many people, the name "flat roof" is associated primarily with high-rise buildings. A flat roof - the pros and cons of which we will consider in this article - has practically not been used in low-rise construction since a dozen years ago. However, today the creation of such a roof in a country house is not a problem: modern materials and technologies make it possible to create a flat roof with proper consumer characteristics and at an affordable price.

A flat roof is much smaller in area than a pitched roof, which saves on materials and construction and installation work.
Thanks to the relatively smaller area of a flat roof, it is possible to optimize costs.
The construction of a flat roof is easier and faster than a pitched roof, since the necessary materials for installation are located right at the feet of the workers on a flat surface. The same can be said about the repair and maintenance of a flat roof - working on an almost horizontal roof is incomparably more comfortable than on an inclined one.
On a flat roof, installation and subsequent service work with all kinds of equipment (air conditioning systems, solar panels, antennas, etc.) are more convenient.
The use of a flat roof is an opportunity to get an additional useful area that can be used as a place where you can relax in the fresh air, play sports, create a garden, flower garden, etc. To date, there are technologies that allow you to cover the roof even with paving slabs or paving stones. The roof, paved with beautiful tiles, combined with a green lawn, garden furniture, a gazebo and a fireplace, can become a place for a comfortable family vacation.

Flat roof houses are very popular right now.

A flat roof, in addition to the advantages, has a number of disadvantages:

As a result of heavy snowfalls, a lot of snow accumulates on flat roofs, which, when melted, often causes leaks.
Sometimes internal drains are required.
There is a risk of clogging or freezing of the internal drain.
There is a need for mechanical cleaning of the roof from too large accumulations of snow.
It is necessary to regularly monitor the moisture state of the insulation and the tightness of the roof.

Varieties of flat roofs

There are four types of flat roofs:

Foundation for a flat roof

In accordance with building codes, a flat roof, the pros and cons of which we discussed above, must have a base in the form of reinforced concrete floor slabs or corrugated sheets.

Subtleties of waterproofing

The durability of the roof structure and its resistance to various negative influences depends on the use of special mixtures and technological processes for the production of roofing materials. Depending on the materials of the roof, it is customary to subdivide into three categories:

Bituminous roofs, as well as polymer-bitumen based on ruberoid. These materials are available due to their low cost. Welded bitumen-polymer compositions are rolled waterproofing and roofing sheets based on synthetics, on both sides of which special bitumen is used, which retains elasticity even at extremely low temperatures (up to -50 degrees Celsius). During the installation of waterproofing, carried out using gas burners, the rolls are fused together. Roof waterproofing can also be carried out with self-adhesive materials based on polymers and bitumen. In this case, the mastic is applied on the bottom surface of the roll and in the process of processing with a solvent acquires the properties of an adhesive. The disadvantage of bituminous roofing is fragility.
Membrane roofs with a base of foil, rubber or polymers. This material has solid strength, is resistant to fires and other negative environmental influences. The membranes are glued to the screed or simply lie on the base, being loaded with ballast, or they are attached mechanically or with glue. To connect the membrane sheets, special welding machines are used that fasten the material with hot air.
Roofs based on liquid polymers, which, after cooling, do not form seams. Such materials are especially often used for structures with complex geometries.

It is very important to make the correct waterproofing of a flat roof.

Whatever material is chosen, the joints between the rolls and the junctions with various roof elements must be waterproof. One of the main components of a successful waterproofing device is a quality sealant. During the period of operation, the roof is subject to negative environmental influences (moisture, hail, stones, strong temperature changes, etc.). Therefore, a high-quality sealant must be resistant to mechanical and thermal influences.

As a sealant, mastic is usually used - putty, which is based on elastic polyurethane resins. After being applied to the roof, the mastic polymerizes, as a result of which a continuous rubber-like membrane is formed, which has waterproofing properties and protects the roofing from mechanical damage.

Mastic is ideal for flat roofing, is safe, has high adhesion to building surfaces, has high resistance to ultraviolet radiation, precipitation and all kinds of microorganisms. It is applied by brush, roller or airless spray - in two multi-colored layers, which allows you to control the quality, layer thickness and even distribution of the sealant.

How to arrange a water drain

Regardless of the materials used, a flat roof must have a certain slope to drain water (usually within 3-5%) that appears on the roof as a result of precipitation. The drainage system should be considered at the design stage of the building. Gutters determine how efficiently moisture will be removed from the roof surface. To prevent freezing of gutters in winter, they are equipped with special thermal cables.

Drains are organized when both external and internal water supply is created, and unorganized. When creating an internal water supply, the roof surface is divided into approximately equal parts of 150-200 square meters each. In places with a slope, drain funnels equipped with baskets for catching garbage are arranged. Typically, the funnels are located in the center of the roof, and the pipes are inside the building.

Flat roof insulation and vapor barrier rules

Flat roofs need insulation. In the absence of a layer of thermal insulation on the roof surface, condensation forms as a result of the contact of warm air masses and the cold surface of the roof. Condensation appears on the ceilings of the house as water spots, and the roof structure is gradually destroyed.

The roof structure involves a base on which a layer of vapor barrier material is laid. The function of the vapor barrier is to protect the insulation from diffuse moisture coming from the premises of the building. The vapor barrier layer includes a glass fiber reinforced membrane (based on bitumen and polymers) or a vapor barrier film. The layer is laid on top of the screed, and along the edges of the roof structure it is wound vertically to a height exceeding the height of the insulating material. The seams are soldered.

Above the vapor barrier layer, a heater is placed, and on top of it - a waterproofing carpet based on bitumen. If expanded clay acts as a heater, then it is necessary to make a cement screed over it, then laying a couple of layers of waterproofing. If the roof is planned to be light (in the case when significant loads are not expected on it), then the waterproofing is simply glued around the entire perimeter of the roof.

For roofs without attics, both external and internal insulation methods are used. The external method is used more often, so its execution is easier. There are two options for thermal insulation: two-layer and single-layer. The decision on which option to apply in practice depends on the calculations for heat engineering and the requirements for the strength of the roof. Thermal insulation boards are placed on the roof structure based on the principle of "spread seams". With a two-layer coating with thermal insulation "in a run", the joints of the lower and upper plates also go. In the area where the plates adjoin the parapet, lanterns and walls, heat-insulating bumpers are created. Thermal insulation materials are attached to the base mechanically (screws, dowels), ballast (pebbles, paving slabs) or glue.

Features of roof ventilation

The roof structure must be equipped with a ventilation system. As a result of a violation of the tightness of the vapor barrier layer, moisture enters the insulation layer. A thick layer of waterproofing prevents evaporation, and moisture accumulates in the insulation. As a result, the material loses its insulating characteristics, and moisture appears in the form of spots on the ceilings of the building. In addition, water causes the waterproofing to swell, and at low temperatures, freezing water tears the waterproofing material from the base. Temperature fluctuations, mechanical damage contribute to the formation of cracks in the roof, the result of which is its flow.

To avoid these problems, the roof must "breathe". For this, aerators are used - special devices in the form of plastic or metal pipes. They are covered with umbrella caps and are evenly distributed over the entire territory of the roof, gravitating to its highest points. The aeration mechanism works on the basis of the principle of different pressure, which is created by air flows, removing excess moisture vapor from under the roof and preventing water bubbles from forming.

Roofing is a responsible technological operation. Any, even a minor mistake in the design or construction of the roof can cause it to leak in the future. Therefore, when creating a roof, special attention should be paid to the correct selection of hydro- and heat-insulating materials, to accurately calculate the upcoming loads on the roof structure, and also to select a team of competent builders.

The choice of a particular design 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.

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

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

In this regard, a flat roof can provide many interesting possibilities, but its use has its limitations.

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

According to the conditions of the location of the plane, there is practically zero wind load (with the correct device without hanging edges) with maximum snow load.

Wherein, roof structure has a complex multilayer structure, which ensures the tightness of the coating and the working condition of the insulation.

The most favorable operating conditions for flat roofs:

Small amount of snow in winter. The most successful use is in regions with warm or little snowy winters, when removing snow from the roof is not difficult.
The strength of the wind does not have a significant effect on the roof, therefore, it is permissible to build such roofs in areas with strong or heavy winds.

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

The use of flat roofs on residential buildings is more common in southern regions, where the problem of high snow pressure in winter is absent.

Flat roof

The structure of the roofing pie

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

The purpose of the roof;
Cover type;
Roofing material.

The decisive factor determining the composition of the roof from the very beginning of construction is the purpose of the roof. It depends on him what material is needed for the construction of the ceiling, how exactly it will be insulated, what is the optimal coating material in this case.

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

The general technology of insulation looks like this:

Base (concrete, wooden floor);
vapor barrier film;
layer of insulation;
The top layer of waterproofing;
Roofing.

This is a general plan, in practice it is often supplemented or complicated in order to more reliably protect against water penetration or the formation of cold bridges.

roofing cake

One of the flat roof options is inverted roof. This is a relatively new kind of pie construction that takes into account the shortcomings of conventional options.

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

To eliminate this phenomenon, an inverted roof is used when a reliable waterproofing carpet (often multilayer) is installed between the ceiling and the insulation.

The composition of the pie is built like this:

overlap;
Waterproofing preparation layer - usually a building primer;
Waterproofing carpet;
Geotextile layer;
Insulation (optimally - extruded polystyrene foam);
The top layer of geotextile;
Ballast bulk layer of gravel.

On top of the ballast layer, if necessary, a hard coating can be laid to maintain a uniform thickness of the ballast and ease of movement.

Inverted roofing cake

Roof base - wood or concrete?

Wood or concrete can be used as the basis 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 truss system is made and the roofing is laid on top. However, wooden floors are also used for residential buildings.

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

CAREFULLY!

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

Most often, for the roofs of residential buildings used, a concrete slab is used as the basis. Such an overlap has a number of significant advantages:

Reliability;
No noticeable deformation from loads;
The penetration of moisture into the material will not cause decay;
Finishing a concrete floor is easier than wood.

Since it is produced outside, the lower surface of the concrete floor (the ceiling of the upper floor) will be open, which allows the use of any available type of finish - from simple painting to the installation of 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 from existing loads.

Photo of the foundations of the roof in section:

wooden base

concrete base

Flat roofs: arrangement of private houses

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

Lightweight. A roof that serves only as protection from rain. It is mainly used for auxiliary buildings for household purposes;
Operated. Such a roof serves as a platform for accommodating various equipment, for arranging 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 recreation.

Depending on the purpose of the roof, the type of overlap 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:

Rafter;
crate;
Roofing (, metal profile, etc.).

Lightweight roof

For a used roof, which is used as a platform for installing solar panels, satellite TV dishes or other equipment, composition is much more complex.:

Concrete floor slab;
Cement screed forming a slope for water flow;
waterproofing layer;
Drainage material that removes water from under the upper layers;
insulation layer;
Geotextile layer;
Sand preparation layer;
Paving slabs.

In this case, paving slabs serve as an external coating, as a durable and cheap material.

ATTENTION!

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

exploited roof

Green roof pie chart:

Concrete floor slab;
Layer ;
Multilayer waterproofing carpet;
insulation;
. It consists of a separating layer of reinforced screed, a double layer of technoplastic (EPP and Green), and a geodrainage rolled layer;
Soil layer with plantings.

In this case, there is a multi-stage hydroprotection that reliably cuts off the insulation material from the upper soil layer. Such a cut-off, 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 surely seep into the lower layers, so the complexity of the composition of the cake 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 with sealing joints with liquid bitumen..

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

Operating surfaces require a more rigid and durable coating. At the same time, the task of hermetic cut-off of the insulation from external influences is not removed, therefore, most often a sand-cement cushion and a working layer - paving slabs are laid on top of the soft roof.

Coating

Installation of an operated flat roof

How to make a flat roof? First of all, you need to decide on the main parameters - the type of roof, device, etc. Consider the option of installing an operated flat roof with a concrete floor and external drainage using gutters:

The surface of the overlap is covered with a layer of sloping concrete screed (decrease). To save concrete, a layer of gravel is first poured with a slope, after which a screed is laid on top. Since this stage refers to "wet" work, then it is recommended to cover the overlay surface with a layer of primer or similar material.
Laying vapor and waterproofing. As a material, various deposited films or rolled membranes can be used. Laying with an overlap, glue the joints with adhesive tape.
insulation layer. Either stone mineral wool or extruded polystyrene foam is used. Insulation is laid in several layers, at least 2 layers. This requirement is due to the need to exclude the penetration of cold through the cracks in the joints of the insulation.
over the insulating layer laying a layer of waterproofing.
Backfilling of the ballast layer - gravel, sand, etc.. The role of this layer is twofold: protection of the film coating and removal of water from melting snow or precipitation in the summer.
over 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 tiles.

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

The device 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, into a technical area for placing equipment, into a recreation area.

All variants of the operated roof require careful arrangement and expensive materials.. The qualitative result directly depends on the qualifications of the people doing the work and on the financial capabilities of the owner of the house.

But do not forget that you can build a flat roof with your own hands.

Investments in an equipped used flat roof will be justified only in regions with short mild winters and low average monthly rainfall. All other issues are solvable and do not cause serious problems.

Waterproofing

Warming

Useful video

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

In contact with

Flat roofs in our time are undeservedly forgotten and are not spoiled by the attention of developers. In private housing construction, they are found mainly in the southern regions, where heavy rains and snowfalls are rare. Hip roofs, on the other hand, have become firmly established in the designs and minds of homeowners.

This state of affairs is explained simply: until recently, builders did not have reliable and durable waterproofing.

Standard roofing material - cardboard impregnated with bitumen, cannot resist moisture and temperature changes for a long time. Even a thick 4-layer coating of it has to be changed after 6-8 years.

Today, interest in flat roofs is starting to grow.

There are several reasons for this:

Economic benefit. The cost of arrangement is lower than that of a hipped roof (simpler design and smaller area);
Additional usable area. There is the possibility of its rational use (flower garden, playground, recreation area, swimming pool);
Availability for maintenance and operation (cleaning drains, installation of air conditioners, antennas, inspection of coatings, ventilation and smoke channels);
The layer of snow plays the role of additional thermal insulation, reducing heating costs.
The original appearance of the building.

Types of flat roofs

Strictly speaking, you will not see a completely flat roof on a building. Any of them has a minimum slope of 1 to 4%, which is necessary for the runoff of precipitation.

There are four types of flat roofs:

unexploited;
exploited;
green (lawn);
combined.

Unexploited roofs are found on industrial buildings.

Exploited roofs have found application in public and private construction. They equip recreation areas, place cafes and restaurants, use them as parking lots and helipads.

Green (lawn) coatings are made to decorate buildings, as well as when there is a shortage of space on the site. In addition to the aesthetic function, they perform an important practical task. A layer of vegetable turf is an excellent heat and sound insulator.

Combined roofs with a flat surface are the most common option. Everyone likes a comfortable outdoor recreation surrounded by green grass and flowering plants.

According to the method of drainage, houses with a flat roof are divided into two types:

With internal drain;
With external water discharge (along the perimeter of the roof).

Internal drainage is cheaper than external drainage, since it does not require a large number of gutters, pipes, funnels and high-altitude installation work. In execution it is more difficult. Errors in creating a slope, poor-quality sealing of joints lead to leaks and a violation of the integrity of the protective layer of waterproofing.

In operation, flat coatings with internal drainage are more profitable. In winter, icicles do not grow on the overhangs near such a roof. Downspouts run inside the building and therefore do not freeze. Cleaning funnels from debris is easier and easier than hanging gutters.

Device Features

According to the method of arrangement and the location of the structural layers, experts distinguish two types of flat roofs:

Classic;
Inversion.

The classic roofing "pie" is equipped according to the following technology:

on reinforced concrete floor slabs, they make a ramp out of a cement-sand mortar;
lay vapor barrier and insulation;
lay a waterproofing membrane or roofing felt carpet;
if the coating is to be used, then the waterproofing is protected with ceramic tiles.

Classic flat roof structure

The main drawback of the traditional design is the vulnerability of the outer insulating layer to solar ultraviolet radiation and temperature changes.

Working on a solution to this problem, engineers came up with the idea of inversion coating. In it, the main structural elements (insulation and waterproof membrane) are interchanged. Waterproofing is hidden under the foam, which is protected from external influences by a ballast layer of gravel or tile trim.

Inversion coating design

Accordingly, the technology of work is changing. A waterproof carpet made of roofing felt or an EPDM membrane is glued onto the slab or spread on it, fixing it at the junction with the parapet.

The slope in this case is created in one of two ways:

Mortar screed on the plate;
Insulation, changing the thickness of its installation.

Installation of thermal insulation on a flat roof

Water intake funnels and pipes are installed at the lowest points of the slope. In addition to them, ventilation is installed to remove water vapor that accumulates in the zone of contact between the vapor barrier and the insulation.

When arranging a coating designed for planting plants, the construct is supplemented with an upper layer of waterproofing. Drainage layers of gravel are poured along it, geotextiles are laid and a fertile layer of earth is poured.

In addition to roofing laid on reinforced concrete slabs, projects have been developed for houses with a flat roof on wooden beams.

Construction technology in this case may include the following operations:

Beams are mounted on the walls in increments of 50-100 cm, fixing them to the masonry with anchor studs. The cross section of the beams depends on the width of the span, the design load and can range from 10x20 cm to 15x25 cm;
OSB boards are laid along the beams, tightly joining them together;
Spread the waterproofing membrane in 2 layers, gluing the joints of the canvases with high quality.
They make thermal insulation from durable (extruded) foam plastic, gluing it to the membrane. A slope for water flow is created by laying the insulation in layers of different thicknesses;
From above, the heat insulator is protected with a cement screed, reinforced mesh or tiled.

Examples of private houses

Among the developers there are many supporters of flat roofs. They are attracted by the ease of construction, the low cost of work and the possibility of placing a site for summer recreation.

A thick layer of snow on a flat roof is not a problem, but additional insulation

The design of buildings with such a roof fits perfectly into the style of minimalism, providing project developers with a wide field for creativity.

Spacious, comfortable and nothing more - the motto of everyone who chooses a house with such a roof. A pitched roof visually makes the building heavier, while a flat one, on the contrary, makes it light and airy.

The appearance of the facade of a one-story house with a flat roof compares favorably with the fairly boring variations of the "teremkovo" character.

On it, most often you will not see gutters and pipes, the water from which gets on the walls and spoils the appearance of the finish. Internal drainage is effective, practical and invisible.

Flat roofs, their types and designs can be classified:

According to the purpose of the surface. It can be operated and non-operated.
According to the method of laying the roofing cake. It can be traditional and inversion.
By type of construction. It can be attic and non-attic.
Separately, ventilated and non-ventilated structures are distinguished.

exploited roof

The exploitable flat roof can be used as a parking lot, helipad, tennis court, swimming pool, green roof and 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 the pool, etc.).

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

Also, due to the nature of the flat roof device, it is highly exposed to ultraviolet rays.

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

The device of the roofing pie of the operated roof 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. From above it is fixed with a concrete screed. Slope up to 3%. It is necessary for high-quality water drainage in the required direction. Sloping is always arranged in front of waterproofing to ensure that water flows through it.
Leveling concrete screed.
Waterproofing. It is made of bituminous, polymeric, PVC materials and sealants. Roofing material is often used, laying it in two layers, while it is important that the joints of the upper and lower rows do not coincide.
thermal insulation. Keeps indoors warm in winter and cool in summer. Requires a careful approach to the calculation of thickness. In the event of a mistake, condensation inside the room cannot be ruled out. If not an inversion type of roof is used, but a traditional one, the insulation must be resistant to steam. Otherwise, there must be resistance to water absorption.
drainage layer. Given the technology of a flat roof, water must flow over the surface into drainage trays. But in other cases, moisture can get into the joints between tiles used as a finishing paving element, or soak into the ground when using a green roof. So that the elements of the roofing cake do not get wet, they arrange a drainage layer that drains water in the right direction.
Further, it all 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 this is a roof-terrace, or a parking lot, a concrete screed under the tile, or other finishing material, goes behind the drainage layer.

Please note that when using a traditional roof, the order of the elements of the roofing cake changes. A vapor barrier is laid along the slope-forming layer, then a heater, and only then waterproofing.

The advantages and disadvantages of this method are discussed below.

Unexploited roof

An unused flat roof is distinguished by its economy. It is not designed to withstand any load other than snow. This allows less careful approach to the choice of building materials.

The device 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 large wave height, such as H-153 and H-158.
Slope layer.
Vapor barrier.
Thermal insulation.
Waterproofing.
Ballast layer of gravel. The thickness of such a layer should be from 10 to 20 centimeters. It is necessary to protect the waterproofing from UV rays and to 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 roofing used.

traditional roof

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

Slope layer.
Vapor barrier. It is necessary to protect the insulation from steam emanating from the room. Otherwise, even in the case of one percent moistening of the heat-insulating layer, a significant increase in thermal conductivity occurs. It is made of specialized vapor barrier membranes and films.
Thermal insulation. It is allowed to use almost all types of insulation, even with a low percentage of moisture resistance.
Next, according to the traditional drawing of the roof of a flat roof, a layer of waterproofing should be laid. Please note that it must certainly be of high quality, since it is absolutely not protected from temperature extremes.

The advantages of a traditional roof are that it guarantees the protection of the heat-insulating layer from getting wet. Firstly, it allows you to use the entire range of roofing insulation. 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 most susceptible to temperature differences, which leads to its accelerated aging. Also, the insulation does not protect the waterproofing from external power loads, which again negatively affects its service life. In general, this type of roof is less durable and requires fairly frequent repairs.

inverted roof

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

Reinforced concrete floor slab, or corrugated board.
Slope layer.
Leveling concrete screed.
Primer for waterproofing, for a better fit. During this process, the screed is carefully inspected for cracks and water bubbles. Cracks are covered with mortar, water bubbles are removed.
Waterproofing.
Thermal insulation.
Further, either a drainage or ballast layer, depending on whether the roof will be exploited or not.

An inverted roof has the following advantages:

Protecting the waterproofing film from temperature extremes. As a consequence, this extends the life of the film in particular, and the life of the roof in general.
The insulation redistributes the power loads on the waterproofing in such a way that it does not affect it.
Extruded polystyrene foam, which is commonly used as thermal insulation for this type of roof, is cheaper than mineral wool used for traditional roofing.
The inverted design of a flat roof allows more repairs, if necessary, replacement, or adding insulation.

There are also disadvantages, which include:

It is permissible to use heaters only with closed cells in order to prevent them from getting too wet.
The need to install a more complex design of gutters.

attic roof

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

The attic roof is a light superstructure, and the attic floor acts as the main supporting structure.
The attic floor and the attic roof are independent of each other and are able to withstand power loads equally well.

The advantages of a roof with an attic are:

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

The disadvantages include:

The impossibility of mechanical removal of snow, 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 melts from above and gradually melts.
This type of roof is more expensive.

roofless roof

More popular is the bare roof. She is:

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

A non-attic flat roof also has a significant drawback:

There is no way to timely determine the violation of the waterproofing layer. These damages appear 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 the constant dryness of the insulation. Used in the traditional type of roofing cake.

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

The height of the vent is at least 1/30 of the width of the building.
Hole diameter not less than 1/150 of the total roof area.
The air inlets must be lower than the outlets.
The holes are evenly distributed across the width of the entire building.

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

This option for arranging the upper part of the 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.

Benefits of flat roofs

Firstly, the installation of a flat roof can be carried out independently, and not to invite assistants or hire professionals, as, for example, when constructing a roof of complex configuration (, four-pitched, etc.). Consequently, they will not have to pay for their work (we are not talking about large areas where it will be problematic to cope alone).

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

Thirdly, a flat surface is much easier to maintain and repair, which also gives tangible savings in the future.

Fourth, a choice of arrangement options. A flat roof can either serve only as a traditional "cover" for the house, or be used (inverted). For example, greenhouses, summer gardens, solariums and the like are mounted on it. There are even heliports. This fully compensates for the inconvenience due to the lack of an attic room.

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 eg.
Debris will constantly accumulate (for example, fallen leaves), so such a roof will have to be serviced more often.
Lack of an attic (mansard) space

What to consider

The maximum load that the roof will experience (for the roof structure). This includes the weight of the frame itself, roofing material, layers of insulation and insulation, as well as possible snow cover. In addition, you need to rely 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, terrace equipment). 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, a barn). Everything is extremely simple here. A so-called “layer cake” is arranged on the surface: vapor barrier, if necessary - insulation 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 equipping a cement screed on top. Slag and some other materials are also used.

Traditionally, roofing material is used for waterproofing, which is covered with bituminous mastics on top. It should be noted that this material will last no more than 5 years, and then you will have to deal with repairs. It is more expedient to lay polymeric materials, for example, membranes, as a "waterproofer". Liquid rubber is also great.

Since the installation of plates requires the involvement of special equipment, with an independent device of a flat roof, you can equip the simplest truss system made of wood.

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

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

If the masonry is old, then a "tape" of concrete mortar is arranged on top of the walls. After that, pre-planned holes are drilled in each wooden blank with a diameter slightly larger than the cross section of the metal "fingers". First, strips of roofing material (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, floor beams are laid. It should be noted that the roof should protrude beyond the dimensions of the house by 50 - 60 cm (required overhang). This will protect both the walls and the blind area from water flowing from it, as well as from raindrops.
Support frame device. Depending on the type, it can be either solid (boards, slabs) or cellular (battens).

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, it is necessary to take into account the weight of such material, since it is an additional load on the truss system.

Waterproofing.

Roof covering.

Overhang finishing.

This is only a general list of necessary activities. The technology for the production of work for each item depends on local conditions and on 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 to its deformation (for example, twisting).
Wood has two significant drawbacks - it burns and is prone to decay. Therefore, before using it, all wooden parts of the structure are pre-treated with flame retardants and antiseptics. It is better to spend money on these funds than to suffer with frequent repairs later.
When installing power plates, you need to constantly monitor their horizontal position using the building level. Otherwise, the roof will turn out to be skewed. If necessary, either the tape is leveled, or a rigid lining is made under the Mauerlat.
To exclude stagnant water on the roof, it is advisable to make it with a certain slope (approximately 3 0 - 5 0). As a rule, the decrease goes towards the rear side of the building. To do this, the height of the front Mauerlats increases, so the floor beams will fall with a slope.