The construction of a gable or hip roof is not always rational and expedient when it comes to outbuildings, industrial and commercial facilities, and sometimes private houses in a modern style. High material consumption, a complex truss system make the construction of these structures an economically unprofitable, protracted undertaking. While flat roof projects greatly reduce construction costs, build quickly and are suitable for almost any structure.
A house with a flat roof is reliably protected from increased wind load. However, without slopes, it cannot quickly drain rain and melt water from the roof surface.
The situation is complicated by the fact that the surface of roofing materials has a rough structure that does not allow moisture and snow to slide off freely. Therefore, a do-it-yourself flat roof device must comply with the stringent requirements of building codes for waterproofing, ramping and construction technology.
The structure of the roofing pie
The need for a high level of protection against moisture forces the roofing materials of a flat roof to be arranged in layers, one above the other, forming the so-called "pie". If we consider its device in section, we can see the following layers:
- Flat base made of concrete slabs or profiled metal sheets. It provides structural rigidity, bears the weight of the roofing pie, transferring it to the load-bearing partitions and, as a result, to the foundation. At the exploited roof, the base should be as rigid as possible.
- vapor barrier. A layer that is necessary in order to protect a flat roof from the penetration of vapors from internal heated rooms into the thickness of the insulation. Settling on thermal insulation in the form of condensate, water irrevocably reduces its insulating properties by more than two times. As the simplest vapor barrier, polyethylene film or bitumen-based coatings are used.
- insulation. For thermal insulation of a flat roof, backfill materials are used, such as expanded clay, perlite, slag, rolled, for example, mineral wool and in the form of plates, in particular expanded polystyrene. By the way, insulation is used not only to regulate the temperature regime, but also to flatten a house with a flat roof. The main requirements for insulation are low hygroscopicity and thermal conductivity, light weight.
- Waterproofing. A flat roof allows the use of rolled materials for protection from moisture: bitumen, polymer and bitumen-polymer. In addition to high waterproofing qualities, they must be resistant to temperature extremes, elasticity, and long service life.
Types of roofing and the nuances of their installation
The device of a flat roof determines the design and nature of use. The following are distinguished into separate types that require a special approach during construction:
Roof installation for unheated buildings
If a flat roof is erected with your own hands for an unheated utility room, for example, a shed, gazebo, shed or extension, the slope is organized using support beams.
They are installed at an angle of 3 degrees, which is 30 mm per linear meter of the length of the beam. Then a base of unedged boards is laid on the beams, fixing them with nails or self-tapping screws.
Roofing material is used as a waterproofing agent - the most affordable material. It is produced and sold in the form of rolls. Carry out the cutting of the waterproofing, cutting the strips so as to lay them in the direction of the slope of the flat roof.
Roofing material strips are gradually laid with an overlap of 10-15 cm and fixed with wooden slats or steel slats every 60-70 cm in the direction of the drain, so as not to block the path of flowing moisture. The flat roof of an unheated room is easily mounted by one's own hands, even by one worker without the help of helpers.
Roof installation for heated buildings
If they are building a private house with a flat roof, which they plan to connect to the heating system, then the work takes place in the following order:
To build a house with a flat roof, the length of which exceeds 6 m, a bar with a section of 150x150 mm or more, or a steel I-beam, is used for the manufacture of support beams.
Monolithic concrete roof
Another option, how to build a flat roof with your own hands, is the use of monolithic concrete. The process looks like this:
Decline process
- the device of a small angle of the roof surface for organizing a drain. Before building a house with a flat roof, it is better to decide in advance which drain you will install, internal or external, and make a drawing.
If provided, water should drain with the help of a ramp into the water-catching funnels, which are located 1 per 25 sq.m or more often. If you make an external drain, then moisture should fall into the gutter. The slope is formed by the following methods:
A flat roof without a proper slope is an unreliable shield between you and the weather. Moisture that has no way out will accumulate on the surface of the roof, provoke the destruction of the roof and leaks.
Video instruction
The shape of the roof, just like the type of its covering, affects the design of the house as a whole. But the roof is not only a decoration of a residential building, it is also its safety, thermal insulation and protection from any weather influences. In order for housing to be cozy and comfortable, the choice of roofing must be approached with skill.
The main forms of roofs that are used in cottage construction are two: pitched and flat. There is no universal answer to the question which one is more practical and safer - each has its own advantages and disadvantages.
A pitched roof is a roof whose surface is inclined towards the outer walls. The slope of such roofs can vary from 5 to 90 degrees. A variety of types of pitched roofs and roofing materials makes it possible to implement the most daring architectural ideas when designing cottages.
The main advantage of a pitched roof is that, due to the slope, it provides an accelerated flow of water. In addition, there is an attic underneath that provides an air gap that reduces heat loss through the roof.
However, a pitched roof has a higher cost due to the need to create a truss system, and since it is part of the overall facade, it requires more expensive materials. Pitched roofing is difficult to maintain: in order to safely move on its surface, additional equipment is needed - stairs or fences. The steeper the slope of the pitched roof, the higher the cost of its repair.
The simplest material for finishing such a roof is slate (from 100 rubles / m²), but it has drawbacks - it leaves a lot of fight, absorbs moisture and quickly collapses, besides this material is harmful to health. However, Russian slate factories are still operating at full capacity.
Materials in the price niche from 150 to 400 rubles/m² are the most widespread in the market of mass cottage construction: metal tiles and various bituminous coatings.
The metal tile has won a leading position due to its affordability and decent aesthetic appearance. Among its obvious advantages are efficiency, long service life (up to 50 years), as well as low weight, which does not create additional load on the walls of the building. In addition, it is resistant to external factors and various kinds of mechanical damage, and is also not afraid of fire. However, there are also disadvantages: corrosion during improper operation, increased noise, high material consumption and poor maintainability. Metal tiles are supplied to our market by domestic companies "Metal Profile" and Grand Line, as well as imported manufacturers - Ruuki, Metehe OY (Finland), Lindab (Sweden), etc.
Bitumen corrugated sheet, outwardly similar to slate, appeared on our market in the early 90s. This is a mixture of bitumen and cellulose with the addition of thermosetting resin and mineral pigments, a durable material (claimed service life - up to 50 years), with up to 25 years of warranty from various manufacturers. Sheets of bituminous "slate" do not contain asbestos harmful to health and are made from environmentally friendly materials, are easy to install and allow installation on an old coating, and in addition, due to the wavy configuration, natural ventilation of the roof is provided.
Bituminous (flexible) tile has all the above advantages, but at the same time it has a wide color palette and leaves a minimum of waste during production. This material is designed for pitched roofs with a slope of 11.3 to 90 degrees. It consists of fiberglass impregnated on both sides with a bituminous binder, with the addition of rubber or plastic, as well as sprinkles (slate or basalt). Service life - from 15 to 30 years. Among the most popular brands are KATEPAL single-layer and double-layer flexible tiles, TechnoNIKOL products Shinglas, Tegola, etc.
Cement-sand tiles will cost from 350 to 500 rubles / m². Its main feature is that it gains strength during operation. This is a piece product of various shapes and colors, so they can lay complex roofs with virtually no waste. The material is durable, but has a lot of weight and special requirements for the truss system. The disadvantages include complex laying technology and high cost.
Ceramic tiles are even more expensive - from 750 rubles / m². At the same time, its service life is from 100 years. It is characterized by a variety of shapes and colors, but at the same time by a large weight and complexity of laying.
flat roof
In a flat roof, the main advantage is the possibility of its operation. On the surface of a flat or slightly sloped roof, you can place a lawn, recreation area, swimming pool, solarium and much more.
The advantages of such a roof can also include convenient installation and ease of maintenance of roof equipment: antennas, air conditioners, solar panels, ventilation shafts, etc. And among the obvious disadvantages is the need for internal drains and regular mechanical cleaning of snow and ice. In addition, constant monitoring of humidity, the condition of the insulation and the tightness of the roof is required.
Not so long ago, a flat roof began to be actively used in low-rise construction, before that it was the lot of high-rise buildings. With the advent of modern roofing materials, it has become possible to provide a flat roof with reliable thermal and waterproofing. When installing a flat roof, you can save on materials and optimize costs due to the fact that its area is smaller than that of a pitched roof.
Another feature of exploited roofs is the need for a rigid foundation, otherwise the integrity of the waterproofing layer is impossible. The base is a screed made of concrete or corrugated board, which creates a place for a drain. The heat-insulating material on the exploited roof experiences serious dynamic and static loads and must be strong enough. If the insulation has low rigidity, a cement screed will be needed on top of it.
But unexploited flat roofs do not need rigid insulation. To maintain the roof structure, ladders or bridges are constructed to help properly distribute the load on the roof surface. Non-operated roofs are cheaper to build, but their service life is shorter than in the case of exploited ones.
One of the most common roofing materials is roofing felt, rolled bitumen materials, polymer-bitumen technologies. Top Tight elastomeric membranes from KATEPAL and a line of materials from TechnoNIKOL deservedly gained special popularity.
Text by Natalia Burkovskaya
A flat roof is a common architectural solution in civil, industrial and private construction. The device of a flat roof has its own characteristics, but the main principle is that the waterproofing layer must be a continuous carpet with certain technical characteristics. The design of roof structures must be carried out in accordance with the current SNiP.
The structure of the roofing cake
If you look at the structure in a section, this type of roof is a multilayer structure, which includes:
The base of a flat roof can be a reinforced concrete floor slab, or a metal profile structure. Depending on the type of base, the material for the remaining components of the roofing pie and the methods of its installation are selected.
The vapor barrier layer is made of rolled or bituminous materials. It prevents the penetration of moisture from the premises into the heat-insulating layer of the roof structure.
A wide range of materials are used as insulation for flat roofs, including:
- mineral wool;
- expanded clay gravel;
- polystyrene boards;
- cement-sand screed.
The waterproofing layer is traditionally made of bitumen-based roll materials. Special mastics or a PVC membrane can also be used.
The waterproofing carpet must have a certain elasticity in order to withstand mechanical deformations of the base and temperature changes.
The structure of the pie depends on the functional features of the roof. The following types of roofing are distinguished:
Flat roof slope
According to SNiP, when installing a flat roof structure, it is necessary to provide for its slope of 1-4 °. This design of flat roofs avoids the accumulation of water on the surface of the coating. For waterproofing, not only prolonged stagnation of water in certain areas is dangerous. Severe deformation and destruction of the outer covering of the roof is the result of repeated repetition of the process of freezing and thawing of accumulated moisture. Various materials can be used for roof slopes. The choice depends on their technical characteristics and installation features.
Lightweight concrete with bulk polymer filler (in particular, extruded polystyrene) is one of the most popular materials. It is quite easy to install, the resulting design has high strength. But the use of this material for leveling should be provided at the design stage of the building, since the significant weight of the concrete used increases the load on the floor, walls and foundation of the building.
Lightweight concrete with a filler of perlite or expanded clay has similar characteristics. This material is cheaper, but its weight is even greater, while the resulting roofing cake is less durable.
The device of a flat roof can be carried out with the use of monolithic heaters, which allow to perform a slope. In this case, sheet material (mineral wool, expanded clay sheets, etc.) is mounted on the prepared surface. Fastening can be carried out on a strong, tenacious glue, which excludes the displacement of sheets over time. Dowels with a plastic spacer can also be used - it is desirable to exclude metal contact with the base of the roof so that the roofing cake does not have cold bridges.
The most time-consuming is the device of the roof with the use of bulk materials for spreading. It is difficult to pour a layer of loose insulation (expanded clay or perlite) with concrete, observing the required angle of inclination of the roof plane, since the granules can move.
An effective, but expensive option for leveling is the laying of foam concrete, followed by the application of a layer of fiber-reinforced concrete. A cake with such a heat-insulating layer is designed for long-term operation. This technology requires the involvement of experienced professionals.
In accordance with SNiP, the slope of the roof is carried out towards the water intake funnels (in the presence of an internal drain), or towards the water intake gutters of the external drainage system, which must be mounted under the roofing carpet or on the outer wall of the building.
Roof knots
In order for the roofing cake to be reliably protected from external influences, special attention should be paid to the places where it adjoins building structures - parapets, walls, pipes, external parts of ventilation systems, etc. There are various nodes of a flat roof, first of all, this is a node:
- adjoining;
- overhang;
- passage through the roof.
The nodes are installed on a reinforced concrete base in places where the roofing pie adjoins the vertical structure with a cut. Manufacturers of roofing materials often develop their own systems, which may have certain design features.
The node must ensure the tightness of the joint and its thermal protection, therefore, the installation of the nodes should be taken very carefully.
The device of an unexploited flat roof
The most common design is the traditional soft roof. In the section, it consists of a bearing base slab, a vapor barrier layer, thermal insulation made of sheet mineral wool and a waterproofing carpet made of rolled bitumen-containing material. The advantages of this design include low cost and easy installation.
More practical unexploited roofs are made using modern materials. PVC membrane waterproofing is very popular. Its installation can be performed in any season, as the membrane is resistant to low and high temperatures. In addition, if the thermal insulation layer has managed to accumulate moisture during installation, the membrane allows it to evaporate. At the same time, the material has high water-repellent properties. In the process of mounting the canvases into a single whole, special welding equipment without an open flame is used.
Covering an unused flat roof can be done using mastic. This is a liquid material that is applied over a rigid, even heat-insulating layer. Mastic is made on the basis of flexible, hydrophobic polyurethane resins. In the open air, after a certain time after being applied in an even layer, it polymerizes, forming a continuous rubber-like membrane. The device of such waterproofing allows you to reliably protect the roofing pie from moisture penetration.
A popular technology is the use of built-up waterproofing. This is an affordable option in terms of price and quality ratio - the durability of such a roof is from 25 years. Bitumen-polymer material based on a rot-proof canvas creates a heavy-duty waterproofing layer. Using this material, it is possible to carry out the device of exploited roofs.
Operating roof device
This design of a flat roof is much more expensive to install, but allows you to profitably use additional space. Today, this type of roofing is in great demand for equipping sports fields, green areas, cafes, parking lots, etc. Installation of a reinforced roof is also necessary if heavy objects, including equipment, are to be installed on the roof. In accordance with SNiP, the roof structure must withstand an uneven high load, that is, it must not deform in limited areas of the area. The section of a flat exploited roof differs from the usual one by the presence of a rigid base in the pie or a special screed over the waterproofing layer. Such a coating excludes punching of the waterproofing carpet with its subsequent destruction.
Inversion Coating Features
The structure of an inverted roof is fundamentally different from other types of roofs. When it is arranged, first of all, a waterproofing layer is mounted on the base. In the context of a roofing pie, it looks like this: base slab, waterproofing, insulation, drainage layer, geotextile. This design allows you to protect the waterproofing material from the damaging effects of ultraviolet radiation and temperature extremes, mechanical damage. Geotextiles, in turn, provide insulation protection. Paving slabs are used as the outer layer. Such a roof is able to withstand high loads, including being used as a parking lot.
It is required to carefully approach the installation of the waterproofing layer, since in order to correct errors, it will be necessary to open the ballast layers.
Installation of a traditional roof structure can be done independently, but for the arrangement of flat roofs using modern materials and technologies, it is recommended to involve specialists with the necessary equipment.
Flat roof device: construction and nodes
The device of a flat roof and its design. The main components and composition of the roofing pie in the section. SNiP for the structure and slope of flat roofs
Flat roof device
For many people, a flat roof is certainly associated with urban high-rise buildings. And very few imagine a country house with a flat roof, which combines the saving of precious space and the possibility of arranging luxurious places to relax on the roof.
Flat roof cake.
In the age of modern building materials and new technologies, it is possible to successfully build private houses with a flat roof, without fear of the surprises of our unpredictable climate. But to feel the full scope of pleasure from a flat roof is possible only when the builders and the customer himself will carefully listen to the advice of a specialist in installation technology and the choice of the necessary components of the roof structure. Only under such conditions will a flat roof serve more than one generation of the inhabitants of the house for a long time, without requiring additional costs.
What are the benefits of flat roof structures?
Until recently, various designs and parts for a flat roof were either very expensive or not sufficiently reliable and functional, which did not at all benefit the popularization of roofs of this type, especially for private developers.
However, life experience proves that, being under the influence of stereotypes, we are too biased towards many problems, as a result of which we do not always judge things objectively. The main thing is to choose the most adequate and correct from the many existing options in order to avoid mistakes.
According to the architects, buildings in the spirit of constructivism, which have a minimum of details and simplicity of construction, are now becoming fashionable again. As a result, the attitude of customers towards a flat roof is changing for the better. In Europe, the design of a flat roof of houses is called a fashionable architectural feature of the project. A house with a roof without slopes looks more modern.
Scheme of installation of a flat roof.
Until recently, for most consumers, a flat roof was a complete taboo. According to some, it was simply tasteless, others were afraid of heavy precipitation in the form of snow, and others believed that a flat roof was an event that required prohibitive financial costs. Nevertheless, experts call a lot of obvious advantages for buildings with this design:
- A flat roof in most cases is equipped as a green recreation area.
- Saving material, because the area of a flat coating is less than the area of a pitched one with the same architectural basis.
- Laying a flat roof is much more convenient than a pitched one - it is easier to mount the cover under your feet than in an unsafe position at high altitude.
- Maintenance of flat roofs is not an extreme climbing activity, but an ordinary procedure.
- Plus, the design of flat roofs makes it possible to obtain additional space without increasing the contour of the structure.
By the way, in developed countries, the possibility of operating a flat roof is most relevant in megacities. Here, more and more often, the problem of ecology began to come to the fore, and therefore raising the elements of gardens, parks, kitchen gardens and lawns from the ground to the clouds has become a very popular thing. And most importantly, if you want your flat roof to be reliable protection, it must be properly installed using durable modern building materials.
Components of a flat roof
Usually, a flat roof is based on a bearing base (it can be a reinforced concrete slab or a profiled metal sheet), on which heat-insulating material is laid along a vapor barrier layer, which is protected from precipitation by a waterproofing layer.
Scheme of an inverted flat roof.
It is characteristic that all the components of the roofing “pie” are of equal importance, and if at least one of them is unsuitable, the entire structure will be damaged. The basis of flat roof installation work is an integrated approach, which consists in determining the type of coating and implementing the best design solution, considering all operational and technological properties, such as fire resistance, water resistance, ease of maintenance, labor costs during arrangement, aesthetic qualities, etc.
Specialists pay special attention to the sealing of seams, the choice of methods and elements of fasteners, the installation of technological units of the coating (junctions to parapets and pipes, drains, corners, superstructures, etc.) and the implementation of through holes. And it goes without saying that the operation of the roof will not depend on any damaging factors if the various components of the structure are made of impact-resistant and weather-resistant materials that are resistant to corrosion processes and UV rays. The exclusion of at least one detail from the overall system is fraught with the most undesirable consequences.
Depending on the type of waterproofing, it can be glued, mechanically fixed or loosely laid. Great attention should be paid to the quality of fasteners and the method of their installation, especially for materials that are laid to the base of the roof with mechanical fastening.
If the rules for laying roofing are neglected, the following undesirable consequences may occur:
- Breakdown of waterproofing by strong gusts of wind.
- Loss of the bearing capacity of the base due to electrochemical corrosion in the “wrong self-tapping screw + corrugated sheet” system.
- Clogged or frozen funnel, which caused the roof to fill with moisture and leaks.
The roofing “pie” consists of the following layers (from bottom to top):
flat roof insulation
Types of flat roof insulation: in one, two and three layers.
The basis of a flat roof is a bearing slab made of monolith, reinforced concrete or metal profiled sheet. From above, it is covered with a vapor barrier material that protects the insulation from water vapor, thus preventing it from swelling from getting wet and ensuring the preservation of all properties. After that, thermal insulation is installed on the roof, which, in turn, is covered with a waterproofing carpet to protect it from atmospheric precipitation.
For a flat roof, one- and two-layer thermal insulation systems are distinguished. Now in construction, a two-layer system is more often used. It works like this: the lower layer, 70-200 mm thick, is assigned the main function of thermal insulation, while the upper one, which is 30-50 mm, is responsible for the redistribution of mechanical loads. Despite being thinner, the second layer is stronger and has a higher density. Such a distribution of flat roof coating layers makes it possible to significantly reduce its weight and, thereby, the load on the floors. The heater must meet the following requirements:
- Low thermal conductivity and water absorption.
- Fire safety.
- High vapor permeability.
- Compressive and tear strength of layers.
Drainage device
Drainage system on a flat roof.
In the arrangement of roofs, it is very important to ensure the free exit of wet vapors from the roofing. Ventilation accessories are essential elements of modern roofing. As a result of human activity, water vapor is continuously generated inside the building. Due to the convective process and diffusion, it rises and, when cooled, condenses in the space under the roof. This process is especially intense in winter. It negatively affects the elements of the roof - both wooden and metal. If too much condensation accumulates, then wet spots form on the ceiling and mold develops. In addition, moisture accumulating in the heat-insulating material reduces its properties, which leads to an increase in the cost of heating the room. To avoid such situations, you need to take care of the proper removal of moisture outside the building.
This task is best handled by special roofing components - a roof fan, otherwise it is called an aerator. The aerator is pipes of different diameters made of plastic or metal, which are covered with caps in the form of umbrellas.
The operation of the aerator is based on the pressure difference caused by the flow of air masses. Its design allows you to remove moisture vapor from under the roofing without damaging the latter.
On flat roofs, aerators are placed evenly over the entire surface at the highest points of the roof plane at the junctions of heat-insulating plates with each other. It is advisable to install aerators at the same time as the roof itself. Otherwise, the cost of installing ventilation increases significantly.
There are a large number of accessories for a flat roof device. The need for their use is due to the design of the roof. For example, in Western countries, much attention is paid to equipping roofs with natural smoke removal devices that enable people to safely leave the building in case of fire.
The reliability of the roof depends on its slope. There are no completely flat roofs, because to drain water, you need a very small, but a slope. For a flat roof, it is measured as a percentage.
It is undesirable to equip roofs with a slope of less than 2 percent. The best option is a slope of 2.5 percent. In this case, the structure is freed from water in a short time, providing more comfortable conditions for the functioning of the roofing material. With a good slope, even a small defect in the roofing will be insignificant.
Another important element of the roof is gutters, which “carry away” moisture and snow along a given route. On a flat roof, an internal drainage system is most often made. Special drain funnels or fittings located on the roof surface effectively drain water in heavy downpours, eliminating roof flooding. Their location and number must be determined taking into account the design rules for these structures and the construction requirements for the design of drains and sewerage of buildings. The required number of funnels on the roof depends on its operating conditions, architecture and rainfall. A special filter is included with the funnel, which protects the drain from foreign objects entering it. So that the water in the drain does not freeze, the mouths of the funnels are equipped with special thermal cables, which guarantees a quick drainage of water at any time of the year.
As a drainage system from a flat roof in private houses, an external drain is more often used, because the internal one is more suitable for constructing flat roofs of large industrial buildings. External drainage is usually carried out using overflow windows, which are installed in the parapet along with roof storm water inlets. Ideally, self-regulating thermal cables should be used in this case, since the storm inlet and overflow window, due to their design, are subject to icing in winter.
When choosing a drainage system, due attention should be paid to the choice of construction material. For example, PVC (polyvinyl chloride) products are less susceptible to icing than metal products.
flat roof construction
The design of a flat roof is a simple and very profitable home improvement option. It is easy to maintain and opens up a lot of new possibilities.
The device and installation of a typical flat roof: a thorough overview of the technological subtleties
The external simplicity of a flat roof is often misleading for beginner home builders. An elementary configuration suggests 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 roofing. In reality, the installation of a flat roof requires scrupulous observance of the rules inherent only to it, which guarantee the flawless operation of the structure and long-term operation.
The specifics of flat roofs
Flat roofs are a separate category of roof structures that do not require the construction of a truss frame. Purely visually, it is an overlap 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 snow is not transferred to the rafters, as in standard pitched systems, but presses directly on the walls of the building. Therefore, flat roofs are strongly recommended to equip houses in regions with a small amount of winter precipitation and high wind load.
In the regions and districts of the fatherland, located in the middle lane and to the north, flat roofs are used mainly in industrial construction. Private traders hoist them over one-story outbuildings, garages, household buildings. For an independent craftsman, a flat roof over a barn or change house is a great option to practice in the field of a roofer.
Briefly about the construction of a flat roof
It is customary to call flat roofs, the only conditional 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 flat with an inclination of up to 5º, a percentage value of up to 8.7%. Even roof structures have a slight slope, creating a clearly horizontal impression. It is formed to divert runoff to catchment 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, stacked in one or two tiers. Required to prevent leakage of heat waves through the upper ceiling, used exclusively in insulated systems.
- A screed created with insufficient rigidity of thermal insulation or in the absence of slopes for a drain.
- Waterproofing that protects the insulation and ceiling from the destructive work of atmospheric water. It is laid with a continuous waterproofing carpet.
- Finishing coating that gives the structure an aesthetic appearance.
The brands of waterproofing materials supplied to the market today successfully perform the functions of a finishing roof. These include numerous rolled and mastic bitumen, bitumen-polymer, polymer varieties. Most of them are laid in one layer.
Due to the slight slope of flat roofs, the use of piece materials in the arrangement is contraindicated, because. multiple joints between elements create a risk of leakage. It is undesirable to use large sheet metal due to the harmful effect on the material of water stagnant on a flat surface during heavy rains and snowmelt.
When using old, well-known types of roofing felt roofing, the finishing roof is arranged in 4 or more layers, the lower of which play the role of waterproofing. A mastic or emulsion bulk roof is constructed in a similar way: the emulsion or mastic is applied in five or more layers, alternating pasty or creamy material with interlayers of fiberglass or polyester.
For laying and fixing the above elements of the roofing pie of a flat roof, a truss structure is not needed. They lay them directly on the base, which can be a ceiling, a screed created on top of it, or the upper plane of the attic structure. For fixing PVC-coated systems, adhesive, mechanical or ballast methods are used. Bulk roofs are applied according to their name, the descendants of the roofing material are melted or glued.
Unlike pitched counterparts, in flat systems there are no battens that create ventilation ducts for washing the insulation with air currents. Therefore, the selection of a constructive solution, materials and their hermetic installation should be approached with due respect and focused attention. A ventilated flat roof only happens when lumber is used in the construction of floors and attics. The latter option is most often used in private construction.
Applicable types of floors
The construction of flat roofs is carried out on floors made of reinforced concrete, wood and profiled sheet. The choice of material for the overlap device depends on the purpose of the roof structure, the size of the overlapped span, possible operation and ease of maintenance.
One of the weighty advantages of a flat roof is the likelihood of organizing an exploited site on it: a place for recreation, a solarium, a green area, a terrace, etc. Of course, the overlap for such objects should be powerful enough. In addition, in the flat family there are roofs that do not involve passing use, therefore, do not require a solid overlap.
Depending on the operational criteria for flat roofs, they are satisfied with:
- Reinforced concrete floors, if the organization of useful space is planned above a large-span brick or concrete box.
- Steel profiled decking over metal beams, if an unused roof is being constructed, spanning spans of any size between walls of brick or other artificial stone.
- A wood-based board created from a board 40-50mm thick, up to 180mm wide. It is used to cover medium and large spans of wooden structures in case of planned operation.
- Chipboards 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 leading in the construction of residential low-rise buildings, because. ahead of concrete and steel rivals in environmental criteria. Note that wood loses in fire resistance. True, fire hazard in low-rise housing construction is not recognized as a decisive factor. In addition, to combat it, there are effective means - flame retardants.
Roll coverings in flat systems with a wooden base then serve only as a waterproofing, on top of which a plank or parquet flooring is arranged. If a flat roof is being built over a brick or concrete box, it is wiser to lay a reinforced concrete floor for an operated object or a profiled sheet for an inoperable one.
It is not always the overlap of a flat roof that serves as the basis for its construction. 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. The structure of the roofing cake of attic roofs is similar, but the layers can be located at different levels.
With or without an attic?
The unconditional enrollment of flat roofs in the category of non-attic structures is fundamentally wrong, 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 roof systems are divided into:
- Atticless, the elements of which are structurally combined with the ceiling. They are completely deprived of an attic superstructure, due to which the budget allocated for their construction is significantly reduced.
- Attic, with an attic superstructure over the ceiling. The minimum superstructure height is 80cm. The construction of attic structures of flat roofs is more expensive, but due to the separation of the ceiling from the roof, the service life of the system is at least three times longer.
In addition to the budget cost, one of the advantages of non-attic systems is the ability to exclude mechanical cleaning. The snow will melt due to the heat coming 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 a railing, which further reduces costs. The minus of the absence of an attic will affect when identifying the causes of leaks, because the state of thermal insulation and other layers of the pie 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, as a result, prolongs the life cycle of structural elements. Elements of the attic system are always available for observation: the ease of inspection is difficult to overestimate.
The undeniable advantage is the possibility of installing insulation after construction, which eliminates its wetting. The disadvantage of flat roofs with attics is the high cost and the need to regularly clean the snow.
Despite the mythical cheapness of non-attic systems, this is a very complex structure that requires experience from the builder, careful selection of materials and adherence to the technology of their hermetic connection. It is better for an independent master to give preference to roofs with an attic, if their construction is not excluded by a design decision.
Subtleties of water drainage
Flat roofs are required to be equipped with gutter systems, which are required to freely drain water all year round at an operational pace. Systems are of external and internal type.
The optimal type of drainage system is determined by the climatic conditions of the construction area:
- External drains are constructed when constructing flat roofs in the southern regions, where icing of drains in the outer pipes is excluded. According to the outdoor type, water is diverted to pipes located outside along the perimeter of the building or to a gutter attached along the lowest overhang. In the middle lane, only flat roofs of non-residential buildings are equipped with external systems.
- Internal drainage systems for atmospheric water when constructing flat roofs are built in the middle lane and to the north. In accordance with the internal scheme, water is transported along slopes or inclined pipes to water points in the center of the roofs. Drainpipes transporting water to the sewer are laid inside the building, but isolated from the premises.
Despite the impressive cost, the construction of an internal drain is mandatory for temperate and northern latitudes, and in the south its arrangement is irrational.
Drainage slope device
If a flat roof slope was not provided 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 inlets 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 better to use to form the slopes should adhere to the following recommendations:
- Slopes on reinforced concrete slabs are done mainly with the help of a screed, or they are combined with a screed with preliminary backfilling of expanded clay or laying slab thermal insulation. On an unused roof, it is enough to lay wedge-shaped mineral wool slabs, produced specifically for the formation of slopes.
- Slopes along the ceilings from corrugated board are formed using metal structures or wedge-shaped insulation.
- Slopes on wooden bases are set constructively, but in the absence of them in the project, it is possible to use wedge-shaped mineral wool.
Due to the serious weight, screeds are poured only for operated 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. On backfill thermal insulation, the screed is poured with a layer of 25-40 mm and a metal mesh is used for reinforcement.
The nuances of the organization of ventilation
Normal ventilation products can be made by the only method - by installing battens on floor beams, similar methods are dictated to us by the construction schemes of pitched structures. It is clear that this method is valid only for wooden options, and for roofs on a concrete base or profiled sheet, it is unacceptable.
The ventilation system of roofing pies for concrete and corrugated board depends on the type and characteristics of the finish coating. PVC roofing is able to spontaneously pass excess moisture from the insulation to the outside, so there is no need to arrange ventilation ducts between it and the insulation.
When using bituminous and bitumen-polymer materials, it is mandatory to install wind vanes over the entire area of a flat roof. The step of the location of these devices depends on the thickness of the insulation. Vanes-aerators provide the removal of moisture from the under-roof space to the outside.
Flat roof construction algorithm
Consider a common case of building an unexploited flat roof over an extension on a suburban area. It will be equipped with an external drain. Thermal 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 construction of a cold flat roof on wooden beams:
- We mark the installation step of the floor beams, for which we will use a board with a thickness of 40-50mm. Installation step from 50 to 70 cm: choose it based on the actual length of the walls. Between the beams should be equal intervals.
- We install the board on the edge, fasten it with nails or corners. The necessary slope to the lowest overhang is created spontaneously due to the difference in the height of the box walls.
- We lay a solid flooring of OSB boards, moisture-resistant plywood or other similar material on the beams. Between the plates there should be a gap of 3-5 mm to compensate for thermal expansion. They are fastened with galvanized screws or ruffed 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 ledge is formed.
- We nail a wooden lath with a triangular section or an ordinary plinth to the sides. These are fillets necessary to drain water from the edges of the roof.
- We treat all wooden elements with antiseptics, fire retardants. After they dry, apply a primer.
- Along the perimeter, over the fillets, we lay an additional waterproofing carpet in a strip. In the case of junctions and pipes passing through the roof, additional waterproofing is installed on the vertical planes adjacent to it in a similar way, i.e. over the fillets.
- We fuse the finishing roofing material chosen for the arrangement, heating its back side with a gas burner.
In the case of applying thermal insulation on the base, a vapor barrier layer is first laid out, the edges of which are wound onto vertical sides. In a kind of pallet formed by a vapor barrier, insulation boards are laid, the thickness of which is calculated in accordance with the requirements of SNiP 23-02-2003. Thermal insulation is attached to the base with self-tapping screws with telescopic devices.
Then waterproofing is laid with entry to the sides and junctions. If one of the latest brands of rolled waterproofing material is chosen for the arrangement, then it will also be entrusted with the duty of finishing.
An impressive range of new polymer-bitumen and polymer coatings are laid in one layer, which saves the installer's efforts and construction costs. Among them are materials that are highly preferred for home craftsmen and do not require the use of a gas burner. They are glued to the mastics or with the help of the back adhesive side, fixed mechanically, laid freely and loaded with ballast.
Video for do-it-yourself builders
To consolidate information about the difficult task of building flat roofs, a video selection will help:
We hope that the information presented by us will help future roofers who decide to practice with their own hands the device of a not so simple design.
There are many conditions for the competent construction of a flat roof, but they must be observed for perfect operation and long service life. Information about the intricacies and specifics of building 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.
Part of the material for writing the article was taken from here:
And for me, a flat roof is the best option, it is preferable to use a roof slab made of expanded clay concrete grade 100, and also do not forget about heat and waterproofing. Still, a flat roof is more aesthetically pleasing to me. And the fact that in winter it will be necessary to constantly remove snow, I think that this must be done from any other roof too. But if we take into account that the material is concrete and plus protection, then when this necessary measure is taken, there is no risk of damage to the structure.
Flat, but still with an insignificant slope of a couple of degrees, or rather. A flat roof to some extent makes it possible to minimize costs. Flat roofs are utilitarian. Thermal insulation and water protection are also excellent. The use of roll materials creates the possibility of saving, ease and speed of installation, a good degree of protection from weather conditions.
Flat roof installation: construction, device, installation, layers, elements
The installation of a flat roof requires strict adherence to the rules for installing elements and a clear arrangement of layers laid during the installation of trussless structures
There are several types of roofing depending on the shape: single-pitched, gable, complex and flat. The last option is the fastest, but at the same time technologically difficult. Familiarize yourself with the technology of self-construction of a flat roof with your own hands.
The device of a flat roof and the principle of its construction
Flat roof - has a fairly simple configuration, and with the right approach, the process of its construction takes a maximum of two days. First of all, decide on the construction technology, draw up a project, purchase and prepare materials for work.
On load-bearing walls, wooden or steel beams are installed that transfer the load from the roof to the walls and foundation.
In addition, beams perform several other important functions, such as:
- retention of the total weight of the attic and ceilings;
- the weight of people who repair and maintain roof structures;
- wind loads, the weight of precipitation that accumulates on the roof.
For the correct selection of the diameter and size of the beam, consider all the loads that affect them. In addition, for the construction of a high quality flat roof, choose the right finish that is durable and performs well.
One of the most important stages is heat and sound insulation. The flat roof of capital buildings consists of floor slabs, on top of which a heat and waterproofing cake is laid:
1. Initially, a vapor barrier is laid on the surface, preventing the penetration of moisture to the insulation. For the manufacture of vapor barrier, reinforced bitumen film based on fiberglass is most often used. The edge of the film is wound beyond the vertical line of the overlap, and all seams are carefully soldered.
2. Installation of insulation is the next step. It is possible to use expanded clay for surface insulation, initially a concrete screed is installed on it, and with a lightweight version of the roof, solid versions of polymer insulation are used.
3. The most important and final layer is waterproofing. The life of the roof as a whole depends on the quality of its execution. Most often, waterproofing of a flat roof is carried out using polymer-bitumen materials.
There are two options for a flat roof, in relation to the type of room for which it is being built:
- flat roof for a heated room;
- flat roof for unheated premises.
The construction of a flat roof over an outbuilding, a shed, a gazebo does not require special skills. To create a stack, a slight slope to one side is enough.
The process of creating a flat roof for a heated room is divided into stages:
1. A boardwalk is installed on the laid beams, which is covered with roofing felt or roofing felt with a large overlap on top.
2. A heater is laid on the roofing material, which is based on expanded clay or slag. When filling the heater, adhere to a certain slope, in relation to the discharge of melt or rainwater from the roof.
3. A screed based on cement mortar is installed on the insulation, at least two centimeters thick. After it has set, the material is treated with a bitumen-based primer. A rolled carpet is additionally glued onto the screed.
It is recommended to create a flat roof with a minimum span, thus reducing the difficulties in its hydro- and thermal insulation. Roofs with a width exceeding 600 cm are recommended to be erected only with specialists. Incorrect calculation of loads on beams leads to terrible consequences: incorrect load distribution and reduced use of roofing materials.
Installation technology of a flat roof made of monolithic concrete
Double-tee steel beams act as load-bearing structures for a concrete flat roof. If the span of the roof does not exceed 500 cm, then beams with a thickness of 15 cm are used to equip the roof.
- crushed stone, fraction 1-2 cm;
- cement brand 400.
The ingredients are combined in the amount of eight buckets of crushed stone and three buckets of cement, four buckets of sand and two buckets of water.
This is followed by the process of mounting the boards on the lower shelves of the beams, roofing felt and reinforcing mesh are mounted on the boards, with a minimum cell size of 10 mm. To connect the intersections of the grid, use knitting wire or a welding machine. The gap between the grid and the roofing material is about 4-5 cm, for this, crushed stone is placed under the grid. The thickness of the concrete layer in this case is at least fifteen centimeters.
At the same time, the strips are laid evenly, it is not allowed to leave an unfinished strip until the next day. This negatively affects the quality of the roof structure. The best option is to fill the roof for one day. After pouring, the surface is compacted with a concrete vibrator or a hand tool. When compacting the concrete, be careful not to deform the mesh.
Next, a polyethylene film is installed on the roof, which prevents excessively rapid evaporation of moisture and cracking of the top layer. After the roof has completely dried, a slope is constructed with the help of a heater to drain water.
Do-it-yourself thermal insulation of a flat roof
A flat roof differs from standard single-pitched and double-pitched types by the need for both internal and external insulation. First, the roof is insulated from the outside, and if necessary, inside.
Previously, rigid heat-insulating boards were used to insulate flat roofs, but due to their heavy weight, they are practically not used at present. This insulation was replaced by heat-insulating materials based on basalt and mineral wool. The thermal conductivity of this material is much higher, and the weight does not make the structure heavier.
In addition, the insulation perfectly resists mechanical damage and is highly fire resistant. The internal insulation of a flat roof is carried out using refractory structures, 2-3 cm thick. Wooden planks are used to mount the plates on the ceiling, on which the plates are fixed with special glue or mastic. Please note that before insulating the ceiling, all lighting fixtures on the ceiling are dismantled.
In addition, as a heater for a flat roof, materials are used in the form of:
- mineral basalt wool - does not need an additional protective screed;
- extruded polystyrene foam - an excellent option for a roof that is in constant use, does not burn, has good soundproofing characteristics;
- polyurethane foam - does not form butt joints, does not burn and is used as a soft roof insulation;
- ecowool - contains cellulose, has an additional flame retardant coating, therefore it has a high level of safety;
- foam concrete - it has a monolithic structure and a long service life, it is similar in structure to foam, ideal for insulating a flat roof without creating significant loads on the foundation.
Flat roof device and technology for creating a roofing pie
In order to get an ideal roofing with good sound, heat and waterproofing characteristics, you must first create a drawing of a roofing pie, which consists of:
- bearing base - concrete or steel beams;
- vapor barrier layer;
- thermal insulation layer;
- waterproofing.
It is possible to change the sequence of layers and add additional materials, it depends on the individual characteristics of the roof and the building itself. Additionally, after the insulation, a textile layer is laid, then covered with rubble and finishing is performed. Such a roof is called inversion and is used extremely rarely, due to the large weight. It is suitable for buildings with high fire safety requirements.
The device of a flat roof implies compliance with all loads that arise during operation. In relation to this indicator, the thickness of each layer in the roofing pie is calculated.
There are several types of flat roofs in relation to the structural characteristics:
- uninsulated roof;
- insulated roof which has open and closed systems 4
- monolithic roofs;
- inverted roofs.
In relation to the operational load, a flat roof can be:
- exploited;
- not exploited.
Depending on the drain:
- flat roof with internal drainage;
- flat roof with external drainage.
Do-it-yourself inversion flat roof
The inverted flat roof is characterized by good performance and high fire safety. The installation technology for this roof option is as follows:
- laying waterproofing;
- installation of thermal insulation material;
- geotextile component;
- drainage system;
- protective bulk coating.
Among the advantages of a flat roof of this type, we note:
- the complexity of the destruction of waterproofing;
- no condensation on the insulation, as it is located on top of the roofing cake;
- ease of repair and replacement of thermal insulation material.
Excessive moisture that forms in the thermal insulation layer is the reason for the deterioration of the protective characteristics of the roof as a whole. Soon it becomes covered with cracks and bubbles, especially in the summer, when the insulation releases moisture. The complete lack of ventilation leads to peeling of the roof from the base.
In this case, we recommend equipping a breathable roof. For the manufacture of roofing, roll materials are used, with excellent tightness and a long service life. Thermal insulation material is installed between the bituminous mastic, and roofing aerators are used for additional ventilation. Among the advantages of this coverage, we note:
- no need to dismantle the flooring, additional strengthening of hydroprotection;
- laying the second layer with a slope leads to improved moisture removal;
- the possibility of using this method both during the initial installation of the roof, and during repairs.
Instructions for finishing a flat roof with your own hands
Flat roof finishing materials must meet certain requirements, such as:
- high level of strength;
- a light weight;
- heat-insulating and sound-proof characteristics;
- resistance to ultraviolet radiation;
- duration of operation;
- ease of installation and maintenance.
Quite often, roofing material with glassine is laid on a flat roof, however, these materials do not have a long service life, they do not tolerate frost well and are destroyed under the influence of temperature fluctuations. Every 8-10 years of operation, the roof is re-coated with roofing material.
New roll-bitumen coatings are gradually replacing roofing material with glassine. This is due to their following advantages:
- excellent performance characteristics;
- ease of installation;
- complete waterproofing of the roof;
- resistance to chemicals, temperature changes;
- duration of use.
There are several varieties of bituminous materials for a flat roof:
1. Fiberglass, fiberglass - is characterized by high strength, resistance to mechanical damage and absolute moisture resistance.
2. Bituminous materials based on polyester or polypropylene. They are used as the bottom layer of protective coatings, have a high density, good waterproofing performance and are used on reinforced concrete floors.
Polymer membrane materials are based on reinforced plastic mesh, rubber and polymer resins. The cost of such materials is much higher than bitumen, however, compared to the latter, they have certain advantages:
- light weight, so they do not load the foundation and foundation of the building;
- elasticity and tendency to stretch;
- duration of operation, which exceeds 50 years;
- do not need to use open flame for installation, in comparison with bituminous materials;
- hot air is used to connect the joints.
Mastic-based materials are ideal for flat roofs. Roll materials, although they have certain advantages, they all create seams that, under increased load, allow moisture to pass through. Seamless mastic roofing does not create butt joints and is characterized by perfect smoothness. Such a roof is called "bulk". This roofing is easy to apply, forming a single sheet, a brush or brush is enough to level the material. Previously, the roof is treated with soil or primer.
Do-it-yourself flat roof video:
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 remains elastic 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 fluctuations, 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, thickness of the layer and uniform 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 thought out 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.
