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 roofing has a fairly simple configuration, and with the right approach, its construction process takes a maximum of two days. First of all, decide on the construction technology, draw up a project, purchase and prepare materials for the work.
On load-bearing walls, install wooden or steel beams that transfer the load from the roof to the walls and foundation.
In addition, beams perform several other important functions, such as:
- retention total weight attic space and ceilings;
- the weight of people who repair and maintain roof structures;
- wind loads, the weight of precipitation that accumulates on the roof.
To correctly select the diameter and size of the beam, take into account all the loads that affect them. In addition, to construct a high-quality flat roof, choose the right finishing coating that is durable and performs well. performance characteristics.
One of the most important stages is heat and sound insulation. The flat roof of permanent buildings consists of floor slabs, on top of which a thermal and waterproofing cake is laid:
1. Initially, a vapor barrier is laid on the surface, preventing moisture from penetrating into the insulation. For the manufacture of vapor barriers, reinforced bitumen film based on fiberglass is most often used. The edge of the film is placed behind the vertical line of the ceiling, and all seams are carefully soldered.
2. Installation of insulation is the next step. It is possible to use expanded clay to insulate the surface; initially, a concrete screed is installed on it, and for a lightweight version of the roof, solid versions of polymer insulation are used.
3. The most important and final layer is the waterproofing layer. The service life of the roof as a whole depends on the quality of its execution. Most often, flat roof waterproofing is performed using polymer-bitumen materials.
There are two options for flat roofing, depending on the type of room for which it is being built:
- flat roof for a heated room;
- flat roof for an unheated room.
Erection of a flat roof over an outbuilding, barn, or gazebo does not require any special skills. To create a stack, a slight slope in one direction is enough.
The process of creating a flat roof for a heated room is divided into stages:
1. A plank flooring is installed on the laid beams, which is covered on top with roofing felt or roofing felt with a large overlap.
2. Insulation, which is based on expanded clay or slag, is laid on the roofing material. When filling in the insulation, adhere to a certain slope, in relation to the discharge of melt or rainwater from the roof.
3. A cement mortar-based screed, at least two centimeters thick, is installed on the insulation. After it has set, the material is treated with a bitumen-based primer. A roll carpet is additionally glued onto the screed.
It is recommended to create a flat roof with a minimum span, thus reducing the difficulties of its hydro- and thermal insulation. Roofs whose width exceeds 600 cm are recommended to be erected only by specialists. Incorrect calculation of loads on beams leads to dire consequences: incorrect load distribution and reduced service life roofing materials.
Technology for installing a flat roof made of monolithic concrete
The load-bearing structures for the concrete flat roof are steel beams of the I-beam type. If the roof span does not exceed 500 cm, then beams 15 cm thick are used to construct the roof.
- crushed stone, fraction 1-2 cm;
- cement grade 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.
Next follows the process of installing the boards on the lower flanges of the beams; roofing felt and reinforcing mesh are mounted on the boards, with minimum size cells of 10 mm. To connect the intersections of the mesh, use knitting wire or welding machine. The gap between the mesh and roofing felt is about 4-5 cm; for this, crushed stone is placed under the mesh. 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 has a negative impact on quality roofing structure. The best option is to fill the roof within one day. After pouring, the surface is compacted with a concrete vibrator or hand tools. When compacting concrete, be careful not to deform the mesh.
Next, a polyethylene film is installed on the roof, preventing excessively rapid evaporation of moisture and cracking of the top layer. After the roof has completely dried, a slope is constructed using insulation to allow water to drain.
Thermal insulation of a flat roof with your own hands
Flat roofing differs from standard single-pitch and gable roofing types by the need for both internal and external insulation. First, the roof is insulated from the outside, and, if necessary, from the inside.
Previously, rigid thermal insulation boards were used to insulate flat roofs, but due to heavy weight, at present, they are practically not used. This insulation has been replaced by thermal insulation materials based on basalt and mineral wool. The thermal conductivity of this material is much higher, and the weight does not burden the structure.
In addition, the insulation perfectly resists mechanical damage and has a high fire safety. Internal insulation of a flat roof is carried out using fire-resistant structures, 2-3 cm thick. To install the slabs on the ceiling, wooden planks are used, on which the slabs are fixed with special glue or mastic. Please note that before insulating the ceiling, all lighting fixtures on the ceiling.
In addition, materials in the form of:
- mineral basalt wool- does not require additional protective screed;
- extruded polystyrene foam - an excellent option for a roof that is in constant use, does not burn, and has good soundproofing characteristics;
- polyurethane foam - does not form butt joints, does not burn and is used as insulation for soft roofs;
- ecowool - contains cellulose, has an additional flame retardant coating, therefore it differs high level security;
- foam concrete - has a monolithic structure and a long service life, its structure is similar to foam, perfect option for insulating flat roofs without creating significant loads on the foundation.
Construction of a flat roof and technology for creating a roofing pie
In order to obtain an ideal roofing covering with good sound, heat and waterproofing characteristics, you must first create a drawing roofing pie, which consists of:
- load-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 individual characteristics roof and the building itself. Additionally, after the insulation, a textile layer is laid, then covered with crushed stone and the finishing is performed. This type of roofing is called inversion and is used extremely rarely due to its heavy weight. It is suitable for buildings with high fire safety requirements.
The installation of a flat roof implies compliance with all loads arising 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 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.
DIY inversion flat roofing
Inversion flat roofing has good performance characteristics and high fire safety. The installation technology for this roofing 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:
- difficulty in destroying waterproofing;
- absence of condensation on the insulation, since it is located on top of the roofing pie;
- ease of repair and replacement of thermal insulation material.
Excessive moisture that forms in the thermal insulation layer causes deterioration in 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. A complete lack of ventilation leads to peeling of the roof from the base.
In this case, we recommend installing a breathable roof. For the manufacture of roofing, roll materials are used, with excellent tightness and a long service life. A heat-insulating material is installed between the bitumen mastic, and for additional ventilation use roof aerators. Among the advantages of this coating we note:
- no need to dismantle the flooring, additional reinforcement of waterproofing;
- 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
Materials for finishing a flat roof must meet certain requirements, such as:
- high level of strength;
- a light weight;
- thermal insulation and sound insulation characteristics;
- resistance to ultraviolet radiation;
- duration of operation;
- ease of installation and maintenance.
Quite often, roofing felt 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 by vibrations temperature regime. Every 8-10 years of operation, the roof is re-covered with roofing felt.
New roll bitumen coatings are gradually replacing roofing felt and glassine. This is explained by their following advantages:
- excellent performance characteristics;
- ease of installation;
- complete roof waterproofing;
- resistance to chemicals and temperature changes;
- duration of use.
There are several types of bituminous materials for flat roofing:
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 properties 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 base of the building;
- elasticity and tendency to stretch;
- service life exceeding 50 years;
- do not require the use of open fire for installation, compared to bituminous materials;
- Hot air is used to connect the joints.
Mastic-based materials are ideal for flat roofing. Rolled materials, although they have certain advantages, all of them create seams that, under increased load, allow moisture to pass through. Seamless roof covering with mastic does not create butt joints and is perfectly smooth. This kind of roofing is called “self-leveling”. This roofing is easy to apply, forming a solid sheet; a brush or broom is enough to level the material. First, the roof is treated with primer or primer.
Do-it-yourself flat roofing video:
The apparent simplicity of a flat roof often misleads novice home builders. The elementary configuration gives rise to thoughts about the efficiency and low cost of construction. Minimum number structural elements is capable of dulling the vigilance of independent performers who are ignorant of the intricacies of the roofing business.
In reality, installing a flat roof requires scrupulous adherence to the rules unique to it, guaranteeing the flawless operation of the structure and long-term operation.
Flat roofs are a separate category of roofing structures that do not require the construction of a rafter frame. Purely visually, it is a ceiling that rests directly on the walls of the building. Due to the absence of stingrays flat roof does not upset the windage that occurs under the influence of gusty winds. However, its configuration does not contribute to the rapid removal of snow deposits from the surface.
The load from the snow is not transferred to the rafters, as in standard pitched systems, but presses directly on the walls of the building. Therefore, it is strongly recommended to equip houses with flat roofs in regions with insignificant amounts of winter precipitation and high wind loads.
In regions and districts of the fatherland located in middle lane and further north, flat roofs are used mainly in industrial construction.
Private owners install them over one-story extensions, garages, and household buildings. For an independent craftsman, a flat roof over a shed or shed is an excellent option to practice as a roofer.
Briefly about the design of a flat roof
It is customary to call roofs flat, the only 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 with a slope of up to 5º flat, a percentage value of up to 8.7%.
Even roof structures have a slight slope, creating a clearly horizontal impression. It is formed to drain wastewater to drainage points or to an overhang.
Regardless of the steepness, the layers of a flat roof are arranged in a strictly defined order:
- Vapor barrier covering the base. It is necessary to protect the insulation from the penetration of household fumes.
- Insulation laid in one or two tiers. Required to prevent leakage of heat waves through the upper ceiling, used exclusively in insulated systems.
- A screed created when the thermal insulation is insufficiently rigid or when there are no slopes for drainage.
- Waterproofing that protects the insulation and ceiling from the destructive effects of atmospheric water. It is laid with a continuous waterproofing carpet.
- A finishing coating that gives the structure an aesthetic appearance.
The brands of waterproofing materials currently supplied to the market successfully perform the functions of finishing roofing. These include numerous roll 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 the risk of leaks.
It is undesirable to use large sheet metal due to the harmful effects on the material of water stagnating on a flat surface during periods of heavy rain and snowmelt.
When using old, well-known roofing felt types of roll coverings, the finishing roof is arranged in 4 or more layers, the lower of which plays the role of waterproofing. A mastic or emulsion self-leveling roof is constructed in a similar way: the emulsion or mastic is applied in five or more layers, alternating pasty or creamy material with layers of fiberglass or polyester.
To lay and fix the above elements of the roofing pie of a flat roof, a rafter structure is not required. They are laid directly on the base, which can be a ceiling, a screed created on top of it, or the upper plane of the attic structure. To fasten PVC-coated systems, use adhesive, mechanical or. Self-leveling roofs are applied according to their name, the descendants of roofing material are fused or glued.
Unlike their stingy counterparts in flat systems there are no battens creating ventilation channels for washing the insulation with air currents. Therefore, the selection of design solutions, materials and their sealed installation should be approached with due respect and focused attention.
A ventilated flat roof is only possible when lumber is used in the construction of the ceiling and attic. The latter option is most often used in private construction.
Types of floors used
The construction of flat roofs is carried out on floors made of reinforced concrete, wood and profiled sheets. The choice of material for the ceiling depends on the purpose of the roof structure, the size of the span to be covered, possible operation and ease of maintenance.
One of the significant advantages of a flat roof is the possibility of organizing a used area on it: a place for relaxation, a solarium, a green area, a terrace, etc. Of course, the overlap for such objects should be quite powerful. In addition, in the flat family there are roofs that do not involve incidental use, and therefore do not require a thorough covering.
Depending on the operational criteria, flat roofs are equipped with:
- Reinforced concrete floors, if it is planned to organize useful space above a long-span brick or concrete box.
- Steel profiled flooring on metal beams, if an unused roof is being constructed that covers spans of any size between walls made of brick or other artificial stone.
- Wood panel made from boards 40-50mm thick, up to 180mm wide. It is used to cover medium and large spans of wooden buildings in the event of planned operation.
- Particle boards and fibreboards on wooden beams, used to cover small spans of wooden and stone buildings. They are used if an unused roof is being constructed.
Lumber is a leader in the construction of low-rise residential buildings, because... are ahead of concrete and steel competitors in terms of environmental criteria.
Note that wood is inferior in fire resistance. True, fire hazard in low-rise housing construction is not recognized as a decisive factor. In addition, to combat it there are effective means– flame retardants.
Rolled coverings in flat systems with a wooden base then serve only as waterproofing, on top of which plank or parquet flooring is installed.
If a flat roof is being erected over a brick or concrete box, it is wiser to lay a reinforced concrete floor for the object in use or corrugated sheet for the one not in use.
The overlap of a flat roof does not always serve as the basis for its installation. In some cases, an attic structure is erected above the ceiling, which can be either a canopy over the base with a roofing pie, or the base itself.
Roofing pie structure attic roofs are similar, but the layers can be located at different levels.
With or without an attic?
The unconditional inclusion of flat roofs in the category of non-attic structures is fundamentally incorrect, although it has strong technical justifications. They may or may not have attics, although they are not formed by installing rafter legs.
Depending on the presence of an attic, flat roofing systems are divided into:
- Without roofs, the elements of which are structurally combined with the ceiling. They are completely devoid of an attic superstructure, which significantly reduces the budget allocated for their construction.
- Attics with an attic superstructure above the ceiling. The minimum height of the superstructure is 80cm. The construction of attic structures for flat roofs is more expensive, but by separating the floor from the roof, the service life of the system increases at least three times.
In addition to the budget cost, one of the advantages of atticless systems is the ability to eliminate mechanical cleaning. The snow will melt due to the heat emanating from the room. Due to spontaneous precipitation, it is not advisable to equip flat roofs without an attic with parapets.
It is enough to install railings, which further reduces costs. The disadvantage of the absence of an attic will affect when identifying the causes of leaks, because the condition of the thermal insulation and other layers of the cake cannot be controlled.
The attic is an air chamber between the ceiling and the roof. This is a kind of buffer that compensates for the difference in temperatures outside and inside the premises.
The presence of an attic reduces the likelihood of condensation forming, and as a result prolongs life cycle structural elements. Elements of the attic system are always available for observation: the simplicity of inspections is difficult to overestimate.
An undeniable advantage is the possibility of installing insulation after construction, which prevents it from getting wet. The disadvantage of flat roofs with attics is their high cost and the need to regularly clear snow.
Despite the mythical cheapness of atticless systems, this is a very complex structure that requires experience from the builder, careful selection of materials and adherence to technologies for their hermetic connection. It is better for an independent craftsman to give preference to roofs with an attic, if their construction is not excluded by the design decision.
Subtleties of water drainage
Flat roofs must be equipped with drainage systems that all year round are obliged to freely drain water at an operational pace. Systems come in external and internal types.
The optimal type of drainage system is determined by the climatic conditions of the construction area:
- External gutters constructed when constructing flat roofs in southern regions, where icing of drains in external pipes is excluded. According to the external type, water is discharged to pipes located outside along the perimeter of the building or to a gutter attached along the lowest overhang. In the middle zone, only flat roofs of non-residential buildings are equipped with external systems.
- Internal drainage systems atmospheric water when installing flat roofs are built in the middle zone and to the north. In accordance with the internal design, water is transported through slopes or inclined pipes to water intake points in the center of the roofs. Drainpipes transporting water to the sewer system are laid inside the building, but isolated from the premises.
Despite the impressive cost, the construction of an internal drainage is mandatory for temperate and northern latitudes, and in the south its construction is irrational.
Installation of slopes for drainage
If the slope of the flat roof was not provided for during the construction of the old roof and the construction of the new one, it must be created. The roof must be inclined towards the water intake funnels by at least 1-2%, approximately 1º.
Those who want to know how to correctly make a slope on a flat roof and what material is best to use to form slopes should adhere to the following recommendations:
- Slopes on reinforced concrete slabs are made mainly using a screed, or a screed is combined with preliminary filling of expanded clay or laying slab insulation. On an unused roof, it is enough to lay wedge-shaped mineral wool slabs, produced specifically for forming slopes.
- Slopes along corrugated floorings are formed using metal structures or wedge-shaped insulation.
- Slopes on wooden bases are specified structurally, but if they are not included in the project, it is possible to use wedge-shaped mineral wool.
Due to their serious weight, screeds are poured only for exploited roofs erected above concrete floor. On a concrete slope, the recommended thickness of the screed is 10-15mm, on rigid insulation panels 15-25mm. For backfill thermal insulation, the screed is poured with a layer of 25-40 mm and a metal mesh is used for reinforcement.
Nuances of organizing ventilation
Normal ventilation can be done using the only method - by installing battens on the floor beams, similar methods are dictated to us. It is clear that this method is valid only for wooden options, and for roofs according to concrete base or it is unacceptable to the professional sheet.
The ventilation system for roofing pies on concrete and corrugated sheets depends on the type and characteristics of the finishing coating. PVC roofing is capable of spontaneously transmitting excess moisture from the insulation to the outside, so there is no need to install ventilation ducts between it and the insulation.
When using bituminous and bituminous polymer materials It is mandatory to install wind vanes over the entire area of the flat roof. The spacing of these devices depends on the thickness of the insulation. Vane aerators ensure the removal of moisture from the under-roof space to the outside.
Algorithm for constructing a flat roof
Let's consider the common case of constructing an unused flat roof over an extension on a suburban site. It will be equipped with an external drain. Insulation of the structure is not expected, because climatic conditions and the purpose of the room below do not require thermal insulation.
The sequence of constructing a cold flat roof on wooden beams:
- We mark the installation step of the floor beams, for which we will use a board 40-50mm thick. Installation step from 50 to 70cm: choose it based on the actual length of the walls. There should be equal spaces between the beams.
- We place the board on its edge, fasten it with nails or corners. The required slope to the lowest overhang is created spontaneously due to the difference in the height of the box walls.
- On the beams we lay a continuous flooring made of OSB boards, moisture-resistant plywood or other similar material. There should be a gap of 3-5mm between the plates to compensate for thermal expansion. They are fastened with galvanized self-tapping screws or rough nails.
- We install a wind board along the perimeter of the roof, the edge of which rises 5-7 cm above the plane of the future roof so that a small side is formed.
- We nail it to the sides wooden slats with a triangular section or a regular plinth. These are fillets necessary to drain water from the edges of the roof.
- We treat all wooden elements with antiseptics and fire retardants. After they dry, apply primer.
- We lay an additional waterproofing carpet in a strip along the perimeter on top of the fillets. In the case of junctions and pipes passing through the roof, additional waterproofing is applied to the adjacent vertical planes in the same way, i.e. on top of the fillets.
- We fuse the finishing roofing material selected for installation, heating its back side with a gas burner.
In the case of thermal insulation, a vapor barrier layer is first laid out on the base, the edges of which are placed on the vertical sides. Insulation boards are placed in a kind of pallet formed by the vapor barrier, the thickness of which is calculated in accordance with the requirements of SNiP 02/23/2003. Thermal insulation is attached to the base with self-tapping screws and telescopic devices.
Then waterproofing is laid over the sides and junctions. If one of the latest brands of rolled waterproofing material is chosen for the installation, then it will also be entrusted with the responsibility of the finishing coating.
An impressive range of new polymer-bitumen and polymer coatings are laid in one layer, which helps to save the paver's effort and construction costs. Among them there are materials that are extremely preferable for home craftsmen and do not require the use of gas burner. They are glued onto mastics or using the back adhesive side and fixed mechanically, laid loosely and loaded with ballast.
Video for DIYers
A video collection will help you consolidate information about the difficult task of constructing flat roofs:
We hope that the information we presented will help future roofers who decide to practice with their own hands in constructing a not-so-simple design.
There are many conditions for the proper construction of a flat roof, but they must be observed in order to perfect job and long service. Information about the intricacies and specifics of constructing a flat roof will help not only determined craftsmen, but also owners of country estates who resort to the services of third-party construction organizations.
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Last revision: 03/01/2016
Various types of flat roofs are quite common constructive solutions, often used in both industrial and private buildings. These structures are distinguished by a number of features that are associated with the type of base used, as well as with the composition of their individual components, forming the so-called roofing pie.
To cover these problem areas, the finished coating kit must include special structural units installed in the abutment areas.
Note! Structural units ensure complete tightness of the resulting joints, and also make it possible to insulate the roof section directly adjacent to this place.
The most common type of flat structures is the classic soft roof, the composition of which in cross-section looks like this:
- load-bearing slab, which is the base of the roof;
- protective vapor barrier layer;
- thermal insulation coating based on mineral wool or expanded polystyrene plates;
- waterproofing carpet covering from any bitumen-containing rolled material.
The advantages of structures of this class include their relatively low cost, as well as the relative ease of manufacturing the protective layer. These indicators can be achieved through the use of modern sprayed materials in its formation, such as PVC-based membranes. It should also be noted that these materials are most often used when constructing the waterproofing part of a complex coating and are characterized by excellent water-repellent properties.
When installing membrane material, first pieces of fabric of a certain length are prepared from a standard roll, which are then laid on the surface of the roof base close to one another.
Note! In order to obtain a single continuous coating from individual pieces of fabric, you will need special welding equipment, the use of which does not generate an open flame.
To prepare the top waterproofing layer of a flat roof, special mastics can be used, which are applied in liquid form over the plates of heat-insulating material. For these purposes, as a rule, compositions made on the basis of hydrophobic polyurethane resins are used. After they are evenly applied to the insulated base, the material polymerizes on its own after some time, forming a continuous coating that resembles the same membrane in appearance.
Another technique for forming a top protective layer involves the use of so-called built-up waterproofing for these purposes, which is the most affordable option for the average performer (in terms of price and quality ratio, among other things). The bitumen-polymer material used in this case, produced in the form of continuous sheets, forms a super-strong surface layer that is not subject to rotting. This material is also very often used in the construction of so-called exploited (inhabited) roofs.
Habitable roof structure
Both by the name and by the design of such a roof, you can immediately guess that it can be used to equip additional living areas on the roof, namely:
- small sports grounds and cafes;
- vehicle parking;
- separate high-altitude landscaping zones, etc.
Note! Let’s immediately say that the arrangement of such a structure will require significant material costs from you, but it allows you to more efficiently use the free space on the roof.
The arrangement of such structures is also considered justified in cases where any special equipment is supposed to be placed on the roof. At the same time, in accordance with the requirements of SNiP, the load on a flat roofing base must be evenly distributed over the surface of the covering, which eliminates the possibility of pushing through the roofing cake in its individual sections.
The design of the so-called inversion roof is significantly different from all known species roofing coverings and therefore requires separate consideration. The procedure for forming a roofing pie in inversion design most often looks like this:
- First, a waterproofing material is laid on a reinforced concrete floor fixed with a bitumen primer and with a slight slope, on which rigid insulation boards are then laid.
- A drainage zone with a special reinforced coating is formed on top of the insulating plates.
- This entire structure is covered with geotextile fabric, which serves as protection against mechanical damage.
- To form the top layer of such a coating, any material included in the project can be used (earth backfill or paving slabs, For example).
In conclusion, we note that while the arrangement of a classic roofing structure (with a roofing tile, for example) can be done independently, then when constructing a flat roof you most likely will not be able to do without the help of specialists who have a full set of all the equipment necessary for the work.
Video
This video shows another technology for making a flat roof:
You can learn about the advantages and features of a flat roof in use from the following video.
Flat roof - common architectural solution in civil, industrial and private construction. The construction of a flat roof has its own characteristics, but the main principle is that the waterproofing layer should be a continuous carpet with certain technical characteristics. The design of roofing structures must be carried out in accordance with current SNiP.
Roofing pie structure
If you look at the structure in cross-section, this type roofing is a multilayer structure, which includes:
- flat base;
- vapor barrier layer;
- insulation;
- waterproofing.
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 cake and methods of its installation are selected.
The vapor barrier layer is made of roll or bitumen materials. It prevents the penetration of moisture from the premises into the thermal insulation layer of the roof structure.
A wide range of materials are used as insulation for flat roofs, including:
- mineral wool;
- expanded clay gravel;
- polystyrene foam boards;
- cement-sand screed.
The waterproofing layer is traditionally made from roll materials on a bitumen basis. Special mastics or a PVC membrane can also be used.
A 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 characteristics of the roof. The following types of roofing differ:
- traditional;
- ventilated;
- exploited;
- inversion
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 covering. It is not only prolonged stagnation of water in certain areas that is dangerous for waterproofing. Severe deformation and destruction of the outer covering of the roof is a consequence of repeated repetition of the process of freezing and thawing of accumulated moisture. Can be used to slope the roof various materials. The choice depends on their technical characteristics and installation features.
Lightweight concrete with loose polymer filler (in particular, extruded polystyrene) is one of the popular materials. It is quite easy to install, and the resulting structure is highly durable. But the use of this material for leveling should be considered at the building design stage, since the significant weight of the concrete used increases the load on the floor, walls and foundation of the building.
Lightweight concrete filled with perlite or expanded clay has similar characteristics. This material is cheaper, but its weight is even greater, and the resulting roofing cake is less durable.
The installation of a flat roof can be carried out using monolithic insulation, allowing for slope. In this case, sheet material (mineral wool, expanded clay sheets, etc.) is mounted on the prepared surface. Fastening can be done with strong, tenacious glue, which prevents the sheets from moving over time. Dowels with a plastic spacer can also be used - it is advisable to exclude metal contact with the base of the roof so that the roofing cake does not have cold bridges.
The most labor-intensive is the installation of a roof using bulk materials for leveling. It is difficult to pour concrete into a layer of bulk insulation (expanded clay or perlite), observing the required angle of inclination of the roof plane, since the granules can move.
An effective, but expensive option for degrading is laying foam concrete followed by applying a layer of fiber-reinforced concrete. A cake with such a heat-insulating layer is designed for long-term use. This technology requires the involvement of experienced specialists.
In accordance with SNiP, the roof slope is made towards the water inlet funnels (if there is an internal drainage system), or towards the water inlet gutters of the external drainage system, which must be mounted under the roofing carpet or on external wall building.
Roofing units
In order for the roofing pie 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 ventilation systems etc. There are various nodes of a flat roof, first of all, this is the node:
- adjacencies;
- overhang;
- passage through the roof.
The units are installed on a reinforced concrete base in places where the roofing pie meets the vertical structure with a cut. Manufacturers of roofing materials often develop their own systems, which may have certain design features.
The unit must ensure the tightness of the joint and its thermal protection, therefore the installation of the units should be treated with the utmost care.
Installation of an unused flat roof
The most common design is the traditional soft roof. In cross-section, it consists of a load-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 simple installation.
More practical non-exploited roofs are made using modern materials. Waterproofing made from PVC membrane is very popular. Its installation can be carried out in any season, since the membrane is resistant to low and high temperatures. In addition, if the thermal insulation layer has managed to accumulate moisture during the installation process, the membrane allows it to evaporate. At the same time, the material has high water-repellent properties. In the process of installing the panels 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 on top of a rigid, even thermal insulation layer. The mastic is made on the basis of elastic, 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 installation 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 affordable option in terms of price and quality ratio - the durability of such a roof is from 25 years. A bitumen-polymer material based on a fabric that is not subject to rotting creates a super-strong waterproofing layer. Using this material you can perform.
Construction of a serviceable roof
This flat roof design is much more expensive to install, but makes it possible to profitably use additional space. Today, this type of roofing is widely in demand for equipping sports grounds, green areas, cafes, parking lots, etc. Installation of a reinforced roof is also necessary if installation is planned on the roof heavy objects, including equipment. In accordance with SNiP, the roofing structure must withstand uneven high loads, that is, not deform in limited areas. The section of a flat roof in use differs from the usual one in the presence of a rigid base or a special screed on top of the waterproofing layer. This coating prevents the waterproofing carpet from being pushed through with its subsequent destruction.
Features of inversion coating
The structure of an inversion roof is fundamentally different from other types of roofs. When arranging it, first of all, a waterproofing layer is mounted on the base. In cross-section, the roofing pie looks like this: base slab, waterproofing, insulation, drainage layer, geotextile. This design allows you to protect the waterproofing material from the destructive effects of ultraviolet radiation, temperature changes, and mechanical damage. Geotextiles, in turn, provide protection for the insulation. Paving slabs are used as the outer layer. Such a roof can withstand high loads, including being used as a parking lot.
All urban multi-storey and industrial buildings are houses with flat roofs. Moreover, today many who love modern style in architecture, they prefer to have a flat roof in their private homes. It really looks stylish, but, among other things, houses with such a roof are more functional - they can be equipped with winter Garden or use the roof as a recreation area in the warm season. Therefore, we immediately proceed to describe the installation stages and consider its structure in detail.
Flat roofing is great for those who use it as an open floor.
Subtleties of installation and design of the roofing “pie”
Installation of a flat roof requires the presence of a roofing “pie”. It has high heat-shielding properties that prevent the attic from overheating in the summer and allow it to retain heat in the winter.
In addition, the roofing “pie” can prevent the formation of condensation, the insulation will be protected from moisture, and ice and icicles will not appear on the roof. It is important to observe its correct design.
- The design of the roofing “pie” involves the presence of several layers:
- load-bearing base;
- vapor insulation layer;
- multilayer insulation;
water protection.
You should start by preparing the base. It needs to be leveled, cleaned, and cracks in the concrete filled with polyurethane sealant, based on a consumption of 180 g per 1 linear meter with a joint width of 5 cm and a depth of 0.3 cm. The next stage is priming using an epoxy primer. On porous surfaces you will need 0.2 kg per 1 sq.m., on non-porous surfaces - 0.12 kg. The primer is mixed with a low-speed mixer until a homogeneous mass is obtained, after which it is diluted by ½ with water. Apply to the surface with a paint roller or brush. After all of the above, the surface of the base can be reinforced. For this purpose, special mastic is applied (14 kg per 1 cubic meter). Before polymerization, a construction bandage is placed on it, and after polymerization, another layer of mastic is placed.
Any roof needs a vapor barrier. For this purpose, polypropylene and polyethylene films are used, which are secured with nails or binders or glued. In this case, you need to maintain a 10 cm gap for ventilation so that steam does not accumulate under the film. Thermal insulation material must adhere tightly to the roof surface, pipes and ventilation units.
Roof insulation and thermal insulation materials
Insulation is responsible for maintaining warmth and comfort in the house. Properly selected thermal insulation materials will not only bring comfort to its walls, but will also allow significant savings on heating. Therefore, you should always pay attention to such qualities of roof insulation as low thermal conductivity, fire safety, vapor permeability, which is necessary for good ventilation of the room; resistance to moisture and various mechanical damage.
- It is very important that the material from which the insulation is made is resistant to point loads. In 80% of cases of roof damage, they are the cause of many problems. The main ones:
- causing serious damage during a thaw due to snow freezing;
- the appearance of “cold bridges” that increase heat loss.
To protect the roof from such troubles, you need to ensure that everything is done in accordance with all rules and regulations of construction, and you also need to control the quality of the materials used. One of the most common materials, without which thermal insulation is indispensable, is stone wool. It is very easy to install and can withstand temperatures of 1000 °C. In addition, polyurethane foam, foam concrete, foam glass and extruded polystyrene foam are often used as roofing thermal insulation materials. Let's take a closer look at each type of material.
Polyurethane foam (PPU) is highly technological and has additional waterproofing properties. However, it cannot be left as a finishing coating, since exposure of polyurethane foam to ultraviolet radiation will make it fragile and reduce its service life; insulation is its main purpose. But this material has good maintainability and can be easily repaired locally. For 1 cubic meter you will need 60-80 kg of polyurethane foam. This amount is due to the fact that polyurethane foam is prone to burning, but its use in this particular ratio reduces its combustible qualities. When exposed to direct fire, the polyurethane foam melts, and when the source of fire is eliminated, it instantly extinguishes.
Foam concrete has a higher thermal conductivity coefficient compared to polyurethane foam, so reliable insulation will be achieved if its thickness and material costs are higher, on average, 250 kg per 1 cubic meter. However, this increases the load on the roof above.
Extruded polystyrene foam is a thermal insulation board material. Insulation with its use has become very widespread and is very popular due to its ease of installation. The slabs are laid tightly over the entire surface and glued together, after which the roof is considered fully insulated.
Thermal insulation using stone wool implies an identical installation method to the previous one. The difference lies in the material itself. Stone wool slabs usually have two densities. Side with increased density often marked with a black stripe. It is this side that the slab should face up.
Foam glass is laid on a flat, dry surface, filled with molten bitumen. Foam glass blocks are placed at a certain distance from adjacent blocks and moved diagonally towards them. To fix the position of the slab and remove excess bitumen from under it, you need to press the middle with your foot. Foam glass is highly durable, resistant to high temperatures and many acids, and has low thermal conductivity, which ensures maximum insulation. However, its high cost often makes it less attractive for use as a thermal insulation material.
It can be done in many ways, but the most popular of them is bitumen. Let's stop there. Bitumen mastic is stirred with a drill with an attachment for 5 minutes. The first layer is made more liquid than subsequent ones. It is applied with a density of 90-120 g per 1 sq. cm. The next layer of bitumen is applied after the previous one has dried, after about 10-12 hours. The more layers there are, the higher the protection.
Features of a flat roof device
The construction of flat roofs divides them into exploitable, non-exploitable, inversion and traditional. The design of an inversion roof differs in that the thermal insulation layer is located above the waterproofing, and not under it. This allows you to protect it from ultraviolet radiation, mechanical damage, and temperature changes. does not imply additional use of the roof; its installation is most affordable. involves the active use of the roof surface (the presence of a sports or helipad, a cafe). In this regard, its installation is more expensive than the installation of unused roofs, but also more durable.
Despite the fact that the roof is called flat, it still has a slight slope (1-4%). This design allows precipitation to disappear on its own. The device of any roofing structure must withstand a load of 200 kg per 1 sq.m., its own weight and the weight of the roof covering. Therefore, they lay it on strong reinforced concrete slabs 4-5 cm wide and 40 x 40 cm in size to increase reliability.