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A do-it-yourself flat roof is most often located on private low-rise buildings, as well as on garage buildings. This type of roofing device is ahead of its competitors. In our article we will tell you why.
Before we talk about how to make a flat roof, we note that the term “roof” and the term “roof” are not the same thing. The term “roof” refers to those elements that are located above the living space of the house. And the roof is a component of the roof, its top layer. It is this that protects the entire building from the effects of atmospheric influences. In these conditions, it is very important to create a reliable roof country house.
Having become familiar with the difference between the terms, we can state that a flat roof is perfect option for home with small area. If the roofing area is large, it is recommended to work as a whole team.
When working on a small house with a small roof area, you can easily do without assistants.
At the beginning of work, secure wooden beams or steel beams to the supporting frames. With their help, you can reduce most of the roof's mass, directing it towards the main walls and foundation.
So, we found out that the main load on the beams is the weight of the roof. But besides this, there are other loads, such as:
Read the advice of experts on forums, look at photos on the Internet - then you will be able to make the right choice of load-bearing beams and avoid critical mistakes. Surely you will be interested in the article flat roof - pros and cons.
If you want to get a reliable and safe flat roof, then choose only a suitable roofing covering (more details: " "). The choice is also important related materials, which can withstand large physical activity, as well as the impact of natural disasters.
Don't forget to check all the technical specifications of the materials. To prevent negative consequences, carry out thorough hydro- and vapor barrier.
There are buildings that do not have heating. These include sheds and gazebos. It is supposed to create a slope on them to drain water from the roof. To do this, you just need to equip the roof at the smallest angle.
When constructing a sloping flat roof, its support beams should be positioned at a slight angle. Boards will be attached to the beams. This will be a kind of basis for rolled roofing felt (more details: "").
To install a rolled roofing felt carpet, you will need a frame made of boards. For this, it is best to use thin wooden planks or steel strips. Secure them along the slope. In this case, the step should be 70 cm. But you should not block the path of water flowing from the roof. The slope percentage of such a roof is no more than 3%. In other words, this is 3 cm per linear meter of length.
Let's consider the nuances when equipping a flat roof for heated houses:
As you study the construction of a flat roof, you will see for yourself that roofs with a large pitch between the support beams require the participation of several people. It is advisable to invite professional craftsmen who will complete all the necessary work as quickly as possible.
When attaching support beams, the distance between them should be maintained. It should be no more than 1 m.
The first step is to calculate the roof span. If it is 5 m, then 15 cm beams are used. Speaking in professional construction language, this is the “fifteenth I-beam”.
To create a monolithic roof, it is recommended to use concrete grade 250. When creating concrete mortar At the construction site, it is advisable to use a concrete mixer. Otherwise, you are unlikely to achieve the correct consistency of the solution. To obtain concrete for a flat roof, you need to mix crushed stone with 20 mm particles and cement, grade PTs-400.
When calculating the components, adhere to the following rules: for eight buckets of crushed stone - three buckets of cement, 4 buckets of sand, and two buckets of water. If there is not enough water, you can add more, this is not critical.
Insulating a flat roof with foam concrete, watch the video:
Next, the boards are fastened to the lower beam shelves. Roofing felt is laid on the dry surface of the boards. Then it is laid on top reinforced mesh periodic profile. The diameter of this element should not be less than 1 cm. The size of the cells is 20x20 cm.
In order not to carry out repairs to the flat roof, the places where the mesh rods are overlayed are secured using binding wire. An option using glue is possible. Ultimately, the mesh should not slide off when pouring the screed.
For complete coverage with concrete mortar, small pieces of crushed stone are usually laid out at the bottom of the mesh. Thanks to this, a gap of 4 cm is left. It is necessary to differentiate the mesh and the roofing felt layer. Pouring is done into the openings between the beams. Let us remind you that their thickness must be at least 15 cm.
After all the steps, the concrete is covered with a polyethylene film. This is especially true if work is carried out during high temperature. By covering the surface, you will prevent moisture from evaporating from the concrete solution. This in turn will protect the top layer from cracking.
The concrete should remain under the film for at least three days. After the concrete mass has completely dried, add a layer of insulation. Don't forget about slopes. The next step is to create a screed and install the rolled carpet.
Today, a common phenomenon is the replacement of a flat roof with a pitched one. However, a flat roof is favored by the fact that it can be insulated both from the outside and from the inside. And after it is completed.
Previously, solid insulation boards were used for insulation. However, with this option the roofing weight increased significantly. Having studied past experience, modern construction moved away from this method of insulation. Today, flat roofs are most often insulated using basalt. mineral wool. This is a fairly lightweight material. In addition, it boasts good thermal conductivity and moisture resistance.
Note that basalt mineral wool is not subject to combustion processes. In addition, it completely tolerates even the most negative impacts nature.
The design of flat roofs looks very simple. The base for a flat roof is wooden or metal beams. They are placed on the walls of the building and will bear the main load of the roof.
If we talk about the load, it is important to understand that in winter a large amount of snow can accumulate on a flat roof, and this in turn adds a lot of additional weight.
Unfortunately, many builders with little experience do not think about this, and calculate the weight of the beams only on the weight of the roof itself and a couple of people.
The best thing to do is look around your area for flat roofs and do your research. So you will know how to make a flat roof
, what material is best to use and what load to provide.
The main task of any roof is to drain rainwater or snow from the slope of the roof itself. If a pitched roof has been installed, then everything will be as usual, precipitation falls into the gutters, and then flows out into the street through drainpipes.
Flat roofs have been used in construction for a long time. They are considered popular for agricultural buildings, production facilities and residential buildings.
involves the removal of drainpipes from the building, inside the building itself. Using a flat system is when there is an inlet slot in the flat roof and downspout system.
The roof plan is divided into several options, which depend on the choice of a specific roof:
Standard flat roof - it is laid on a thermal insulation layer. The weakness of this option is waterproofing, because it is influenced by precipitation and temperature changes. It is also affected by the load when walking.
For large cities, these roofs are considered the best. In megacities, as a rule, there are few undeveloped plots of land. Using such a roof will allow you to build a cafe on top or, for example, a green area, and so on.
A similar exploitable roof for underground parking is made as follows:
1. A waterproofing layer is applied to the screed.
2. After this layer, a filter and heat-insulating layer is applied. The most commonly used is gravel. Paving slabs are laid on it, and the result is a regular courtyard area.
is becoming increasingly popular for green roofs. These are, so to speak, gardens and roofs - terraces on which large shrubs, trees, and lawn grass are grown. You can use another way by creating a soil layer.
But the most complex roof counts mixed version when green areas need to be alternated with pedestrian paths. During roof design, several systems are used. Popular ones are mechanical system, inversion system, ballast system and adhesive system.
The ballast system is usually performed on roofs with a slope of no more than 15%. This system can be used if there is a strong foundation underneath it, since the ballast will create a large load.
The inversion system is similar to a ballast system. The only difference between these systems is the waterproofing layer. In an inversion system, it is laid under the insulation. Here it is necessary to use insulation that will not absorb water. This system will be ideal if you plan to create green spaces or a place to relax.
Mechanical system - mounted on complex roofing installations or on a slope of more than 15%. These systems are very lightweight. Their weight is approximately 2 kilograms per 1 square meter.
If the slope is large, use an adhesive system. It is also used if the roof has non-standard shape with many angles. It is done by gluing.
mainly performed in areas where precipitation is low. This is especially true during winter, since snow remains for a long time on a flat roof in large quantities. Therefore, when there is heavy snowfall, it is recommended to construct flat roofs taking into account heavy snow loads, using beams with a large cross-section and better fastening of the elements.
The slope of such a roof can be from three to fifteen degrees, but it is better to use a slope of around five degrees. To make the slope the way it is needed, expanded clay, slag or other similar materials are used in the insulation that regulates it.
The flat roof system of heated houses looks like:
The slope of this roof is provided by the entire structure. Therefore, it is necessary to carefully monitor the installation and maintain the slope every 1.5 meters. You can also make rafter frames that are not too steep, with a slope of about 10 degrees, installing them along the entire length of the roof, and attach the sheathing to them.
Flat roof system for heated houses:
Flat roof construction system:
1. Instead of wooden beams, you need to lay metal I-beams, the height of which is 12-15 cm. A continuous plank flooring is laid on the lower part of the beams, and a layer of roofing material is laid on it.
2. The next step is to install a double, that is, two rows of reinforcement frame (with a cross-section of approximately 10 mm) lengthwise and crosswise (cell size 20×20 cm). The reinforcement frame should not come into close contact with the roofing felt.
3. Then all this is poured with concrete to a height of 15 cm, maybe a couple of centimeters less. If the weather is not cool, but hot, then it is better to cover the poured concrete with a polyethylene film so that it does not dry quickly, but smoothly and evenly. The film must be removed after three days.
4. If you do not have this film, then you need to carefully monitor the drying of the concrete and, if necessary, water it with water. When the concrete is completely dry, you will need to create a slope using insulation. Next, the screed is performed and the rolled carpet is laid. That's it, the monolithic flat roof is done!
Wooden rafters are the internal frame of the roof, which, as a rule, belongs to the oldest and most popular structures. They are produced as wooden houses, and in brick houses with flat roofs.
What is the best type of rafter wood?
For construction wooden flat roof
, you will need a coniferous tree - spruce or pine. They have general properties, namely: elasticity, strength, durability, resistance to external environment. And such wood is considered very soft, which is easy to process. These types of wood are low in cost.
Fir wood can also be used, but it is less resistant to moisture with a low level of strength. The most best choice Larch wood is considered. But this type limited in terms of felling, and therefore the cost of this wood is high.
To obtain a monolithic wooden element, you need to saw the logs several times, after which their front and side parts will be flat and take the shape of a rectangle.
Wood moisture content should be at least 20 percent. Freshly cut wood with a moisture level of more than 30 percent will be 60-75 percent less in strength than dry wood, which, of course, reduces the strength of the elements made from such wood.
For the construction of frames wooden flat roof , it is better to use first grade wood, since the use of second and third grades is recommended after careful treatment with antiseptics.
According to their structure, rafters are divided into inclined and hanging.
Sloping rafters are erected in houses with a middle load-bearing wall or columnar intermediate supports. These rafters are erected if the distance between the supports, that is, the span itself, does not exceed 6.5 meters. The width, which is covered by inclined rafters, can be increased to 10-12 meters if there is one additional support, and with two additional ones - up to 15 meters. The location of the rafters directly depends on the size of the building.
Slanted rafters are easy to assemble.
Hanging rafters have the appearance of two rafter legs, which are in the same plane and connected at the bottom by a tie. These rafters rest only on two supports, which are on the edge. The support for the lower ends are special bars called mauerlats.
A tie made of wood or metal connecting the rafter legs reduces the load. It can be installed at the base of the rafters or higher.
To construct such a structure, pre-made rafters (separately) are installed on the attic floor, and then, using additional elements, perform their assembly.
If installed over several spans of one roofing structure inclined and hanging rafters, then they can be erected in alternating order. Where there are no intermediate supports, hanging rafters are used, and where there are, inclined rafters are used.
can be produced externally and internal ways. It is worth noting that internal insulation is simpler, when the heat-insulating material is glued to the surface of the ceiling. The installation of thermal insulation from the outside is somewhat more difficult, so this type of work must be performed by a professional roofer.
In order for the room to be thoroughly insulated, a material 10 cm thick is sufficient. For this type of work, it is more convenient to use mineral wool slabs, which can simply be laid joint-to-joint with each other, since they have a rectangular or wedge-shaped shape. When laying thermal insulation, special attention should be paid to the installation of a vapor barrier layer.
The presence of a vapor barrier can be guaranteed by the existing gap between thermal insulation layer and roofing or laid polyethylene film. The presence of a vapor barrier layer is especially important since the temperature difference internal space building and outside, can lead to the appearance of dampness, which is fraught with serious consequences not only for the roof, but also for the entire building.
Before starting work on insulating a flat roof, it is necessary to find out what condition its supporting structures are in and, if necessary, bring them into proper condition. At the same time, you should check the integrity of the electrical wiring laid in the attic.
Having completed the repair work, we begin the installation of the thermal insulation itself.
External insulation of a flat roof:
It is possible to insulate the outside of a building’s flat roof using rigid insulating boards. Panels in the form of a solid base are placed on the beams of the supporting structure. Heat-insulating boards are laid on the panels, which are pressed down with some kind of weight.
The seeming ease of performing this type of work at first glance is complicated by the fact that you have to work at height. In addition, special care is required when moving on a roof surface covered with roofing materials, since the slightest damage to them can lead to further leaks. Therefore, it is better to entrust this work to professionals.
Internal insulation of a flat roof (or insulation from the ceiling):
In most cases this is the best solution. The process of such insulation in itself is not difficult. It is only necessary to solve the problem with future lighting of the room in advance. It is better to choose fire-resistant polystyrene foam tiles as insulation; as a rule, they are glued to the ceiling, with wooden planks secured between them for greater stability.
During the construction of urban high-rise buildings and industrial facilities, the basis of a flat roof is usually a reinforced concrete slab. But for private houses, especially frame and wooden ones, such a choice is most often unacceptable. In this case, a flat roof is built on wooden beams. Its main advantage is its light weight, which reduces the load on the walls and foundation. The installation of such a roof is simpler and cheaper than using heavy reinforced concrete slabs. But the functionality is the same. Therefore, this option of a flat roof is often chosen by those who want to build it with their own hands.
The main share of such roofs falls on private houses and cottages, whose owners value futuristic style, convenience and practicality. Also - for covering verandas, terraces, balconies, garages. As a rule, all these buildings are wooden or frame, requiring lightweight design roofs. But this is not a mandatory rule. The wall material can be anything - brick, aerated concrete, foam concrete, etc. In this case, wooden beams often crash into the mauerlat - wooden beam, running along the perimeter of the walls and connected to them using anchor bolts or studs.
Flat roofing is especially attractive to developers because its horizontal surface can be used as a usable area. Moreover, this is possible even for a roof with wooden beams at its base.
Of course, you shouldn’t use the freed up meters for a parking lot, swimming pool or tennis court. Still, such projects require a more monumental foundation. And here is the open terrace, observation deck, wooden beams can easily support a home greenhouse. The main thing is to make the calculation correctly and not skimp on the thickness of the lumber.
The following types of flat roofs can be built on wooden floors:
That is, all possible types - without restrictions.
Unused roof– ordinary, completed with a waterproofing finishing coating. It is intended solely to protect the premises from conditions environment and does not set itself other goals. It is forbidden to use it as a place of rest, move in large groups, or install terrace furniture and flowerpots. The covering of such a roof is designed for the fact that 1-2 people will periodically climb onto it, solely for maintenance of the structure.
Operable roof- already more interesting and more complex. In addition to its direct protective functions, such a roof plays the role of additional usable space for the homeowner. The design pie ends not with waterproofing (prone to damage), but protective coating– paving stones, decking, wooden flooring, paving slabs, turf layer, crushed stone or gravel.
Inversion roof– inverted roofing, a qualitatively different option. It can be either exploited or unexploited. Its peculiarity is the inverted order of placing layers in the pie. If in ordinary roof The waterproofing is laid on top of the insulation, whereas in an inversion roof the opposite is true. The waterproofing lies under the insulation, and the vapor barrier is completely excluded from the structure of the cake. Due to this, the waterproofing is protected from the street environment and its service life is increased.
However, under the influence of unfavorable street conditions, the insulation becomes insulated, so the choice of this type of insulation in inversion roofs is limited. Only EPS (extruded polystyrene foam) and nothing more! This material has virtually zero water absorption, high density and strength. On top of the EPS in inversion roofs is loaded with washed gravel, paving stones, paving slabs or a turf layer.
An interesting option for exploited roofs (including inversion ones) is green roof . It can also be supported on wooden beams. The pie of such a roof ends with a soil layer on which plants are planted. There are other elements that are not used for other types of roofs: a drainage layer (gravel, expanded clay, crushed pumice or geomats), a filtration layer (geotextile).
The frame of the described roofs is made of wooden beams laid like an interfloor ceiling. Full size can be used wood lumber or composed of several elements (glued). Often beams are made from boards with a section of 100x150 mm.
The beams are laid with support on the walls, similarly interfloor ceilings. If the building is wooden or frame, then the beams rest on the upper crown of logs or top harness. If it is brick or block, then on a pre-fixed Mauerlat. A timber with a cross section of 150x150 mm or 150x100 mm is usually used as a Mauerlat. It is mounted on the upper chord of the walls using anchors or studs. To protect the wooden Mauerlat from the wall material, 1-2 layers of waterproofing (roofing felt) are laid between them.
Cuts are made on the beams for the Mauerlat, they are laid and secured with metal corners or nails. The pitch between the beams is maintained at 50-120 mm (depending on the calculated load).
When installing beams, it is important to ensure a roof slope of 1-6°. Despite the fact that the roof is called flat, it is not absolutely horizontal. A slight slope is necessary to ensure that water moves towards the drain and thus prevents it from stagnating.
You can create the required slope in the following ways:
Most often, the first option is used, that is, the beams are immediately laid with a slope. The easiest way to do this is to attach a strong beam or board along the top of the load-bearing wall, which will raise the frame(s) on one side. Instead of a transverse purlin, you can also install short radial beams extending from the central double diagonal beam.
A flat roof pie on a wooden frame can have a different structure. There are many design options, many of them are posted on the Internet. And they will all work!
Option 1. Roof with insulation over beams
Flat roof insulation layers can be laid on top of the beams. For example, a proven working option (classic roofing with insulation):
When using EPPS insulation and PVC membranes simultaneously in the structure, a separating layer (geotextile, fiberglass) must be laid between them. The fact is that these two materials are incompatible and when they come into direct contact, the PVC is destroyed.
The polymer membrane is fixed to the insulation mechanical method or loaded with ballast. Crushed stone or gravel (for all types of roofs), paving stones (for maintained roofs), and soil (for green maintained roofs) are used as ballast. However, when choosing ballast, you should soberly assess the reliability of the wooden frame and its maximum load.
If as finishing coating It is assumed that a built-up waterproofing or EPDM membrane with adhesive fixation will be used; a change is made to the scheme discussed above. It consists in laying sheets of plywood, OSB or DSP between the insulation and waterproofing.
This results in the following diagram:
Installation of a built-up roof traditionally requires the use of a gas burner, therefore, according to existing fire standards, it is not allowed on wooden structures. Therefore, they act as follows. The first layer of waterproofing is nailed or glued to a wooden base, and the second layer is fused, as it should be. It is also convenient to use euroroofing felt with a special adhesive base, for which it is recommended cold installation without heating with a burner.
Installation membrane roofing on a wooden base is shown in the video:
Option #2. Roof with interbeam insulation
Another principle of assembling a flat roof pie is associated with laying insulation in the space between the beams. This option is more convenient than the first if EPDM membranes with adhesive fixation or fused roofing are used as waterproofing.
The following roofing pie scheme is often used:
In principle, a similar system is used in the formation of classic pitched roofs.
Option #3. Roof with internal insulation
In this case, sheets of plywood, OSB or DSP are sewn onto the supporting structure (beams), and waterproofing is laid over them. The remaining insulating layers of the roofing pie are sewn on the side of the room.
A rough ceiling (made of boards or sheet materials), planks are screwed to it, perpendicular to the load-bearing beams, in increments of 40 cm. Polystyrene foam boards are placed between the planks, gluing them to mastic or glue. A vapor barrier film is sewn to the insulating layer. Cover the insulation cake with a finished ceiling.
Design diagram (top to bottom):
An example diagram would look like this:
Option #4. Inversion roofing on beams
Or you can go against all “traditional” solutions and build an inversion roof on beams. Due to the fact that the waterproofing will be covered with insulation, that is, protected from loads, exposure to oxygen, UV rays and precipitation, its service life is significantly increased.
When constructing an inversion roof, you can use the following diagram (from bottom to top):
The principle of inversion roofing is often used to install green roofs. For example, you can do this:
The wooden base of a flat roof, along with its advantages, also has features with a minus sign. This is an increased fire hazard and low load-bearing capacity (compared to reinforced concrete slabs).
To waterproof such a roof, it is advisable to use materials that do not require hot installation. Ideally, polymer membranes. When choosing built-up bitumen-polymer coatings (from the Euroroofing felt series), the first layer of material is installed mechanically, and the second - by fusing. To minimize the possibility of fire in structures during installation, as continuous cladding(on which the waterproofing is laid), it is recommended to use non-combustible DSP boards.
When constructing serviceable and ballasted roofs, you should also remember that excessive load on a wooden base can be fatal. Therefore, if the load-bearing capacity of the beams used is small, lightweight materials should be selected for the finishing coating - decking, deck board, rubber paving slabs(rubber mats), etc.
Flat roof on wooden beams: device, diagrams, expert advice
How often does a situation arise when a developer is tempted to use the flat roof of a garage or technical room attached to a house as open terrace. A terrace on a flat roof above a heated room in use is one of the most difficult elements, both for design and construction. In this article we will talk about how to properly install an open ventilated terrace on a used flat roof on wooden floor beams above a heated room.
Basic requirements for the design of a flat exploitable roof - terraces.
1. Flat ventilated roof - the terrace above the attached heated room should be located outside the perimeter of the main building. According to Norwegian building codes, only partial embedding of a flat roof - a terrace - inside the contour of the main building is allowed - to a depth of no more than 1 meter. This condition is necessary for the passage of a sufficient amount of air in all parts of the ventilation gap.
2. When installing a flat roof - terrace, a ventilation gap is created using double sheathing. On the open sides of a ventilated flat roof, terraces must be provided ventilation holes. The passage of a sufficient amount of air is necessary to remove excess moisture from the insulation.
3. The design of a flat roof in use - a terrace - should not allow moisture from precipitation to enter the ceiling. To do this, you need to use special wind and waterproof membranes, but they should not prevent steam from escaping from the insulation. For flooring under a waterproof floor covering of a flat roof - terrace, you need to use moisture-resistant materials, for example, OSB-3 class boards.
4. If there is a danger of melting large quantity snow on the surface of a flat roof - terrace, then in this case it is necessary to provide an internal drainage system built into the ceiling itself. In southern regions, with little precipitation in the form of snow, hanging gutters and wall-mounted gutters can be used. drainpipes, this also applies to those cases when the terrace is placed under a common roof with the house or the thickness of the thermal insulation layer is at least 250 mm.
5. The floor level of the used flat roof - terrace should be approximately 50 mm below the floor level of the corresponding floor inside the house.
Load-bearing structure of the exploited flat roof - terraces
The floor, which is the base of a flat roof - terrace, must consist of wooden beams with a cross-section that meets the requirements of strength and rigidity. The moisture content in the load-bearing beams during floor assembly should not exceed 15%. For reference, we present the moisture content of wood: room-dry (with a humidity of 8-12%), air-dry artificially dried (12-18%), atmospheric-dry (18-23%) and damp (humidity exceeds 23%). If the moisture content of wood when sold at the base is designated as “natural”, this means a moisture content of more than 23% (up to 80-90%).
When calculating the overlap of a flat roof, you need to start from the minimum possible height of the beams that make up the load-bearing frame of the terrace. The use of beams with the minimum possible height for flat roof floor beams is necessary in order to lower the floor level by approximately 50 mm in relation to the floor of the corresponding floor inside the house. To increase bearing capacity floors, you can reduce the pitch of the load-bearing beams (more efficiently) or increase the width of the beams (less efficiently). When choosing the cross-section of the load-bearing beams for the floor of a flat roof in use - a terrace, you must remember that the height of the beam must be equal to the calculated thickness of the thermal insulation layer.
The floor of the exploited flat roof is terraces.
The main structural elements of a flat roof-terrace located under a continuous deck are shown in the figure above. For flooring under a waterproof floor covering, you need to use moisture-resistant materials, for example, OSB-3 class boards. As a waterproof floor covering, you can use roofing felt, rolled sheets of galvanized steel and other similar materials.
To protect the waterproof coating from mechanical damage, impregnated shields are used (impregnated with an antiseptic under pressure in the factory) wooden planks. The width of the mounting bar must be at least 73 mm. There should be no sharp edges on the mounting block facing the waterproof coating. Before installing wooden panels, an additional gasket is placed under the mounting block to protect the waterproof coating. Wooden panels are laid so that they do not interfere with the outflow of rainwater. There is no need to attach wooden panels to the floor beams; they must be easily removable in order to allow cleaning. The design of the flooring of a flat roof - terrace can be seen in the figure below:
Fencing of an exploited flat roof - terraces
The fencing of a flat roof - terrace must be designed in such a way that the health of children and adults is not damaged due to falling over the fence or getting stuck in it.
If the exploited flat roof - terrace is located at a height of more than 0.5 m from the ground level, then the height of the fence must be at least 1 m. The height of the fence is measured from the top level of wooden panels.
The fastening of the fence posts must be strong enough to withstand the design horizontal load of 0.4 kN/m 2. The standard values of horizontal loads on the handrails of balcony railings in SP 20.13330.2011 “Loads and Impacts” (Russia) and DBN V.1.2-2-2006 “Navantazhennya i vplivi” (Ukraine) are set at 0.3 kN/m. n. The spacing of the fence posts should be no more than 1.2 m.
Between the fencing posts of the flat roof in use, vertical or horizontal filling is performed. To protect children from falling over the terrace fence, the distance between the vertical elements of the fence should be no more than 100 mm. To prevent children from climbing onto the fence, the distance between its horizontal elements should be no more than 20 mm.
To ensure horizontal rigidity and strength of the fencing of the exploited flat roof - terrace, a massive handrail is mounted on top of the racks. In places corner connections the handrail is assembled using metal corners or plywood overlays in such a way that it is not visible from the outside. The terrace fencing must be firmly fixed to external wall. The fence posts are attached to outside flat roofs - terraces so as not to damage the wind and waterproof membrane. If it is impossible to fasten the fencing of the existing flat roof - terrace to the wall, or its length is from 8 to 10 m, then before choosing the section of the racks and the type of fastening, it is necessary to carry out a detailed calculation taking into account the current moments and loads.
Many people imagine a flat roof as integral part urban high-rise building. However, in fact, a flat roof is more common on country houses.
Today there are many building materials and new technologies. They allow the construction of private houses with a flat roof. At the same time, the climate of our country does not affect future construction at all.
Flat roof construction: advantages
Until recently, one could come across overly expensive designs and parts for flat roofs. However, they were not reliable and had low functionality. Naturally, this was not an advantage for flat roofs, and private developers often refused to build a roof of this type.
But if you judge objectively, then from all the variety of options you can find the most suitable element for yourself. It must be the most adequate and reliable. This will help avoid mistakes in the future.
Based on construction statistics, today there is a revival of interest in buildings in the spirit of constructivism. Let us remind you that this is a minimum of parts and simplicity of design. In these conditions, customers are beginning to reconsider their own decisions - in favor of a flat roof. Note that in Europe the design flat covering houses is a kind of construction fashion. In their opinion, houses with roofs without slopes look impressive.
Until recently, many consumers had a negative attitude towards flat roofs. Some considered it tasteless, others were frightened by heavy precipitation in the form of snow, and still others believed that a flat roof was too expensive a solution.
However, experts have long identified many obvious advantages of buildings with this design:
It is also worth noting that the flat roof design involves obtaining additional area. At the same time, do not increase the outline of the structure.
Note that in developed countries, flat roofs are more often installed in megacities. This is due to the fact that environmental problems are increasingly coming to the fore. In these conditions, raising elements of gardens, parks, vegetable gardens and lawns, as they say, “from the ground to the clouds,” is popular. Well, don’t forget that if you want to get a flat roof, you need to install it correctly and select durable modern building materials.
The design of flat roofs and its elements
The load-bearing base is the main thing in a flat roof. The basis is reinforced concrete slabs or metal sheets from profiles. Thermal insulation material is laid on the base. The place of its attachment is a vapor barrier layer. It, in turn, must be protected by a waterproofing layer.
All elements of the roofing pie for a flat roof are of equal importance. So, if at least one of them is unsuitable, the entire structure will fall into disrepair. The basis of installation work for a flat roof is an integrated approach. It is due to the fact that it is necessary to determine the type of coating, and then implement the best design solution in practice.
It is important to take into account all operational and technological properties:
Questions about sealing seams and the choice of fastening methods and elements deserve special attention. It is also necessary to qualitatively equip the technological components of the coating: connections with parapets and pipes, drains, corners, superstructures. Finally, you need to make through holes. When installing a flat roof, it is advisable to install components made of impact-resistant and resistant materials. They will protect your roof from damage during operation. In addition, today it is important to have materials that are resistant to corrosion processes, as well as the effects of UF rays. If you exclude at least one part from the system, irreparable consequences may arise.
Depending on what kind of waterproofing you have, it can be either glued, secured, or simply laid. Pay attention to the quality of the fasteners and the method of their installation. You need to be especially careful with materials that are laid to the base of the roof with mechanical fastening.
If you ignore all the rules for laying roofing, you may encounter undesirable consequences:
Composition of the roofing “pie”:
Flat roofing on wooden beams and its insulation
The load-bearing slab is the base of a flat roof. It is made of monolith, reinforced concrete or metal profile. The top layer of the slab is covered with a vapor barrier material. It protects the insulation from water vapor. Thus, the material does not swell and retains all its original characteristics. The next stage is the installation of thermal insulation. It is also covered with a carpet of waterproofing to protect the material from weathering.
For flat roofs, thermal insulation systems with one and two layers are provided, installed on wooden floor beams. Today, the two-layer system has become widespread. The principle of its operation: the main function is assigned to the bottom layer, which has a thickness of 70 to 200 mm, taking into account wooden trusses ceilings and their size. The function of the top layer (from 30 to 50 mm) includes the redistribution of mechanical loads. Note that the second layer is much stronger and denser than the first. It is no coincidence that a wooden flat roof has such a distribution - this significantly reduces its weight and, consequently, the load on the floors.
Insulation requirements:
Setting up a drain
Particular importance should be given to the free escape of wet vapors from the roof covering. In these conditions, ventilation accessories play a big role. As you know, water vapor forms inside a building. Due to the convective process and diffusion, it rises upward. Having met cooled air, it begins to condense in the space under the roof. This process is especially relevant in winter. At the same time, it negatively affects roofing elements - wooden and metal. If condensation accumulates excessively, the ceiling becomes covered with wet spots and mold. But that is not all. Among other things, moisture accumulates in thermal insulation material and deteriorates its properties. This in turn increases the financial costs of heating the rooms of a country house. Eliminate similar situations there is only one way - you need to remove the moisture outside the house.
To perform this task, special roofing components are designed - a roof fan (aerator). These are a kind of plastic (metal) pipes with different diameters. They are covered with special caps that resemble umbrellas. The operation of the aerator is associated with pressure differences caused by air mass flows. Thanks to its unique design, the aerator removes moisture vapor from under the roofing. In this case, the structure itself is not damaged at all.
All types of flat roofs have aerators. The latter are located evenly over the entire surface at the highest points of the roof plane. Roof aerators can also be found at the junctions of thermal insulation slabs. As a rule, the installation of these elements occurs in parallel with the installation of the roof. If this is not done, ventilation costs can increase significantly.
Components for installing a flat roof are available in large quantities. They are influenced roofing materials for flat roof. For example, in the West, roofs are most often equipped with natural smoke removal devices. This allows people to leave the building in case of fire without risking their lives.
Thus, it is not recommended to install a roof that has less than a 2% slope. The best option is a flat roof slope of 2.5%. In this case, the design removes water within a short time. At the same time, roofing materials for flat roofs are in more comfortable operating conditions. It should also be noted that even if there is a small defect, this will not harm the slope.
Calculation of the location and number of such elements is carried out in accordance with the rules for designing structures. It is also necessary to take into account the construction requirements for the design of drains and sewers of houses. The number of sinkholes is influenced by operating conditions, architecture, and the amount of precipitation. In addition to the funnel, there is a special filter. Its task is to protect the drain from foreign particles. The water that gets into the drain does not freeze due to the presence of special thermal cables. Thus, the gutter can be used in any season.
External drainage eliminates water from a flat roof. This is due to the fact that most often it only works on flat roofs of large industrial complexes. External drain represented by overflow windows, which are installed in the parapet along with storm drains. Another necessary element is self-regulating thermal cables. It is more suitable for winter, since the storm drain and overflow window are often subject to icing.
When choosing a drainage system, pay special attention to the material of construction. For example, products made from PVC (polyvinyl chloride) are almost not subject to icing, unlike metal products.
The design of a flat roof on wooden beams, how to choose roofing materials
IN Lately Interest in projects of low-rise houses with a flat roof is growing. Architects and developers are attracted to these unusual buildings, on which you can equip an observation deck or even set up a real hanging garden. Of course, in practice everything turns out to be more complicated than in theory.
Designing a flat roof raises many questions regarding its cost, choice of materials for insulation and waterproofing, organization of water flow, maintenance and operation of the roof. Finding answers to them is not so easy. The fact is that domestic private companies working in the field of cottage and country house construction are well familiar with the most popular design - pitched, but, as a rule, they have no experience in constructing flat roofs, which are designed completely differently.
What immediately attracts attention is the fact that the area of a flat roof is smaller than a pitched roof, which means that less materials will be required, and the work will be cheaper. However, this statement is true only for regions with a warm climate and low snow load, moreover, if we are talking about unused roof. IN middle lane In Russia, to ensure the reliability and durability of a horizontal roof, it is necessary to apply rather expensive engineering solutions.
It turns out that 1 m 2 of a flat concrete or steel base, the load-bearing capacity of which will allow it to withstand the weight of snow cover, costs 2-2.5 times more than a wooden beam structure of a pitched roof. The difference in the volumetric consumption of insulation is leveled due to the fact that a flat roof requires more expensive high-density material. There is still hope to save on roofing, however, modern polymer membranes are the optimal waterproofing for horizontal roofs- they are no cheaper (and sometimes much more expensive) than flexible tiles.
There is no need to install snow guards, but you cannot do without a roof hatch and a drainage system. If you try to cut costs according to the estimate, you will subsequently have to pay the price of having to repair the roof every 10-15 years.
Finally, it should be taken into account that flat roofs are appropriate only on houses of modern architecture - with a large glazing area and complex finishing with the latest facade materials. That and the other one won't be cheap at all.
As a rule, in low-rise housing construction, the flat roofing is a prefabricated or monolithic reinforced concrete slab.
Reinforced concrete slabs (PB, hollow PC, PV, etc.) are capable of covering a span of up to 9 m in length and can withstand a pressure of 8, 9 or 12.5 kPa (this value is indicated by the last digit in the product labeling). They can serve as a “base” for any roofing pies, including those with a top layer of paving slabs or fertile soil. However, to install the structure, it will be necessary to ensure that a truck crane can enter the site (while steel beams and flooring can be easily lifted using winches). The depth of support of the ceiling on the wall depends on the material of the latter - for example, for brick this parameter should be equal to the thickness of the slab. Before proceeding with the installation of the roof, it is important to seal the joints of the elements with mortar and additionally seal them with elastic polymer tape. Monolithic w\6 ceiling is erected from heavy concrete using removable (for example, from OSB boards on jack stands) or permanent (from corrugated sheeting) formwork. It is reinforced with a two- or four-level welded frame made of rods with a diameter of 12 mm. Dimensions monolithic slab are not regulated (unlike prefabricated), which provides the architect with freedom when designing a building; other advantages are the absence of seams, the comparative simplicity of the installation of passage units (chimney, ventilation ducts) and high load-bearing capacity (subject to compliance with technological regulations).
In principle, when constructing a floor, you can use a combination of beams (wooden, steel) and load-bearing corrugated sheeting. However, experts do not recommend using wooden beams (with the exception of those made of LVL beams with a cross-section of 200 * 100 mm) in regions where the snow pressure exceeds 1.2 kPa (about 120 kgf/m2) - that is, in most of the territory of the Russian Federation. Roofing made of steel I-beams and corrugated sheets with a wave height of 60 mm and a wall thickness of 0.7 mm allows you to cover a span of up to 12 m and withstand a pressure of at least 6 kPa. But in general it is less durable than concrete, and is relatively rarely used in individual construction. It makes more sense to use corrugated sheeting as permanent formwork, which, by the way, does not replace the need to build a reinforcement frame.
In the low-rise sector, mostly flat roofs without attics are in demand, because the attic requires additional costs and disrupts the architectural proportions of the house. This means that the roof must protect against winter cold and summer heat. A common feature of flat roofs is that the heat-insulating layer is located on top of the supporting structure (in pitched roofs it is usually located between the rafters). If you insulate the room from below, the dew point may shift into the thickness of the ceiling, which will lead to a reduction in the service life of the latter.
There are special requirements for thermal insulation for flat roofs. The material must not only have a low thermal conductivity coefficient, but also have good resistance to mechanical loads - both distributed (pressure from the overlying layers of roofing cake, equipment, snow) and local ones that arise during installation. In addition, it is important that the material has hydrophobic properties and is non-flammable. At the moment, there are several ways to install thermal insulation: using mechanical fasteners, adhesive and free laying. In addition to traditional two-layer insulation, single-layer installation is becoming an increasingly popular solution.
As for roofing options, there are dozens of them. Suffice it to say that more than 40 “recipes” are given in SP 17.13330.2011 alone. At the same time, coating and insulation manufacturing companies are offering more and more new engineering solutions. However, they are always based on one of two circuit diagrams- traditional or inversion.
Traditional flat roof design in general terms it is as follows: laid on top of the load-bearing base vapor barrier film(polypropylene, polyethylene, 6-item-polymer), followed by insulation, for example, mineral wool slabs with a compressive strength at ten percent deformation of at least 30 kPa, in one or two layers with a total thickness of 200 mm. Above is a separating layer (for example, made of polyethylene film), along which a reinforced slope-forming screed is poured (a flat roof must be given a slope of 2-3% towards the center or edges to ensure water drainage). The dried screed serves as the basis for a roll or mastic waterproofing coating.
Other options are also possible.
For example, a slope-forming screed can be located at the very bottom of the pie; in this case, the roofing waterproofing is fixed with gravel ballast, paving slabs on supports or special dowels. Some materials, say the “RUF SLOPE” system (Rockwool) or “TechnoNIKOL Slope” allow you to do without a screed altogether: the slabs have variable thickness, and with their help it is not difficult to create smooth changes in level to ensure water drainage.
Flat roofs are divided into unexploited and exploited. The former visit only for inspection, prevention and repair; For this purpose, a roof hatch is installed, to which an attic ladder leads. The roof in use in cottages most often serves as a terrace, that is, a durable wear-resistant coating must be laid on it, and the load-bearing base is designed for increased loads. A type of exploitation is a roof with landscaping, laid with a turf layer on top of the main thermal-hydro-insulating pie; Usually there are paths and a recreation area on it. A convenient exit to the roof in use should be provided, for example from a vestibule superstructure.
Inversion roof it is designed differently: in it, insulation resistant to constant exposure to water (usually extruded polystyrene foam - EPPS) is located on top of the waterproofing. At the same time, the latter is reliably protected from mechanical damage and is located in the positive temperature zone (freezing-thawing cycles are destructive for almost any material). It is easy to turn an inversion roof into a usable one, for example, by covering the insulation with a drainage layer of sand and gravel and laying paving slabs. The disadvantages of the design include more complex drainage. However, we need to talk about gutters separately.
For roofs in use, as well as roofs installed in regions with harsh climatic conditions, the inversion circuit is ideal. Since the waterproofing layer is located under the thermal insulation layer, it is protected from mechanical influences, as well as from temperature changes and UV radiation, which significantly extends the service life roofing system. Waterproofing materials based on modified bitumen must be laid in at least two layers - this technology is more common, and in addition, it allows you to level out possible errors when fusing the material. For polymer membrane One layer is enough, and reliability is ensured by automatic welding equipment, which greatly increases the speed of work. In addition, when installing a polymer membrane, an open flame is not used, so the technology is considered safer.
Rolled materials based on modified bitumen are usually fused gas burner(a), while it is difficult to prevent minor flaws that could cause leakage (if the second layer is missing). The quality of welding of PVC coating strips (6) is much easier to control
The flat roof is equipped with a parapet (attic) 30-90 cm high, which helps ensure organized drainage of water; on a roof in use it also serves as a safety fence. At the same time, the design of gutters should be approached very responsibly, because if you make a mistake, a huge puddle can form above your head, which can lead to leaks and damage to supporting structures.
As a rule, the choice is made in favor of an internal drain. Such a system is less exposed to the atmosphere and is therefore more durable and reliable than an external one. Let's talk in more detail about its main elements. Water intake funnels are installed on low areas of the roof. As a rule, on roofs with an area of up to 150 m2, two funnels are installed - the main one, connected to the riser, and the emergency one, with water discharged through a hole in the parapet. With an increase in the number of funnels and risers, the reliability of the system increases, but its cost also increases.
Flat roofs are in demand in modular construction. Among the advantages of this method are the affordable cost and high speed of construction of housing, as well as the possibility of gradually increasing its area
For inversion and green roofs, special funnels with drainage rings have been developed to collect moisture from the intermediate layers. The after-receivers must be equipped with electric heating based on a self-regulating cable - then they will properly perform their function during alternating thaws and frosts.
In a new type of system, the so-called siphon-vacuum system, special funnels are used to prevent air from being sucked into the water flow. Thanks to them, the speed of fluid movement in the pipe (and hence the throughput of the latter) increases, which makes it possible to reduce the diameter of the system elements. However, for low-rise buildings, the savings turn out to be insignificant; moreover, such systems require more accurate calculations than gravity systems.
The drainpipe is made from sewer pipes - polypropylene, polyvinyl chloride, and it makes sense to use sound-absorbing products, for example RAUPIANO Plus (REHAU), or soundproof the riser, otherwise you will hear the murmur of water for hours. The riser is connected to the funnel using an elastic coupling. When laying pipes, the number of bends and the length of horizontal sections that reduce throughput systems. A drainage pipe laid in the basement or insulated underground connects the riser to the rainwater drainage system or ensures the discharge of water into a linear drainage tray.
In the second case, there is a risk of clogging the outlet with ice, so the riser should be equipped with a “winter” outlet to the domestic sewer (the latter should be equipped with a water seal). The outlet pipe is cleaned through a collapsible connection or an inspection module.
When choosing the standard size of elements of a traditional gravity system, they proceed from the intensity of rain in a given area, focusing on SP 32.13330.2012.
The external drainage system is more vulnerable than the internal one, and also affects the appearance of the facades, but does not require holes in the roof and ceilings and does not eat up usable area Houses. Water is discharged through parapet funnels or pipes embedded in the parapet, under which classic funnels (like on a pitched roof) and down pipes attached to the walls with brackets are installed. When calculating, it is assumed that for each square meter The roof area should be 1-1.5 cm of the cross-section of the drainpipes. Elements of the external system can be made of PVC, steel, copper, zinc-titanium.
Since ancient times, turf-covered roofs have been used in countries with moderately cold and humid climates, and the green carpet performed the main moisture-protective function in them.
As part of the modern green roof concept, a layer of fertile soil with plants is needed to give unusual features appearance of the building, decorate the terrace roof and extend the service life of the coating by covering it from ultraviolet rays. In addition, it absorbs rainwater, unloading the gutters, dampens the sound of rain, protects the rooms on the upper floor from overheating in the summer and reduces heat loss in the winter. It is believed that landscaping almost doubles the life of a roof. Its disadvantages include an increase in loads on the supporting structures of the building and an increase in construction costs.
In addition, a green carpet needs care, the intensity of which depends on the selected plant species. If you do not pay due attention to the plants, they will freeze and die from drought.
To green the roof, you should lay on top of the main waterproofing layer (in an inversion scheme - on top of the insulation) an additional cake made of materials that will ensure protection of the waterproofing layer from roots, filtration and drainage of rainwater. For these purposes, special films, dense geotextiles, gravel bedding or drainage and moisture storage membranes made of high-density polyethylene, for example PLANTER GEO or Delta-Floraxx, are used.
Then a mixture of minerals and fertilizers is poured - the so-called soil substrate. You can prepare it yourself by adding fine expanded clay (5-15%), sand (about 20 96) and fertilizers to a light soil mixture of neutral peat. As for plants, the easiest way is to limit yourself to meadow forbs and drought-resistant ground covers - sedum, herbaceous carnation, thyme.
They do not need to organize an irrigation system, and the thickness of the soil layer can be only 6-12 cm (this type of roof is called extensive). If you plan to walk on the roof among ornamental shrubs, you will have to provide irrigation and increase the soil thickness to 20-40 cm. Such a roof is called intensive, it creates a significant additional load on the floor, therefore it must be provided for at the design stage of the building.
Sheet and piece coverings are unsuitable for flat roofs: water will inevitably seep through the joints of the elements. Therefore they use rolled materials and mastics. Let us give a brief description of them.
ROLL REINFORCED POLYMER-BITUMEN ROOF.
The mechanical strength of these materials is several times higher than that of roofing cardboard (roofing felt, roofing felt). And modifying additives increase resistance to moisture, air and ultraviolet radiation. The material is glued to the base with mastic, fixed mechanically or (most often) fused. There are coatings for the lower layers of the roof (Tekhnoelast EPP, Uniflex EPP, Bireplast TPP, etc.) and for the upper ones (Tekhnoelast EKP, Uniflex EKP, Gidrostekloizol TKP, etc.). The latter are sprinkled with mineral chips, which reduce the risk of fire and additionally protect against mechanical damage and UV exposure. The cost of waterproofing of both types is low - from 65 and from 150 rubles, respectively. per 1 m 2 and the average service life of a roofing carpet is 15-30 years.
ROLL PVC MEMBRANES, for example, Sikaplan WP, Logicroof, Ecoplast are strong and durable (up to 30 years without repair) and do not support combustion. However, they require a professional approach to installation (the joints of the strips must be carefully welded with hot air) and are relatively expensive - from 320 rubles. for 1 m 2. It is important to consider that this material does not tolerate contact with bitumen.
ROOF COVERING OPTIONS
Traditional with external drain
1 - overlap; 2 - slope-forming screed; 3 - vapor barrier; D, 5 - mineral wool insulation; 6 - waterproofing; 7 - drain
with internal drain
1 - screed; 2 - PVC membrane; 3 - EPPS; 4 - funnel with drainage ring; 5 - drainage membrane; 6 - sand; 7 - paving slabs
Eliminates snow avalanches and reduces the risk of falling ice. + Provides convenient access to chimneys, ventilation risers, antennas; Compared to pitched ones, it is easier to maintain and repair. + Can serve as a recreation area or terrace.
Slightly less susceptible to wind loads than pitched. + Allows you to implement the principle of phased modular construction (to make an extension to a house with a pitched roof, you need to solve a difficult architectural and design problem).
– Requires significant costs
on a foundation with high load-bearing capacity.
– It is more susceptible to atmospheric factors than pitched, so durability is guaranteed only if expensive materials are used.
– Requires increased attention to the arrangement and condition of the drainage system (especially with internal drainage).
House with a flat roof with your own hands - design and design options, Do it yourself - How to make it yourself
How often does a situation arise when a developer is tempted to use the flat roof of a garage or technical room attached to a house as an open terrace. A terrace on a flat roof above a heated room in use is one of the most difficult elements, both for design and construction. In this article we will talk about how to properly install an open ventilated terrace on a used flat roof on wooden floor beams above a heated room.
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