Insulating a flat roof is the most important task, with which you can significantly reduce heat loss and, therefore, energy costs. In addition, the heat-insulating layer prevents the formation of condensation, which allows you to significantly increase the maintenance-free operation of the roof. But that's not all! Thanks to the insulated roof, a favorable microclimate is created in the rooms located directly below it.
- mineral wool on a basalt base (for example, Tekhnoruf 45 or Tekhnoruf 60 from the TechnoNikol company), which can be used without a protective screed.
- extruded polystyrene foam(foam) is ideal for used roofs. It perfectly absorbs sound, but is flammable and not recommended for insulation soft roofs.
- polyurethane foam is an excellent option for roof insulation. Ideally applied, non-flammable, does not form seams or gaps.
- ecowool is insulation made from cellulose and treated with fire retardants, which transform a highly flammable material into a non-flammable one. In stores and on construction markets look for brands Ecowool, Ecowool and Unisol.
- foam concrete is a new material that resembles concrete in its solidity and durability, and foam in structure and weight. The ideal way to insulate flat roof and not create a significant load on the supporting structures.
Flat roof installation
The so-called “pie” of a flat roof consists of the following layers:
- load-bearing base (concrete, metal profile)
- vapor barrier
- heat insulating layer
- waterproofing
Insulating a traditional roof with mineral wool is a popular method. In this case, the insulation is placed under a layer of waterproofing.
The sequence of layers may be different if it is planned to install an inversion roof. In this case, the “pie” will look like this:
- load-bearing base
- waterproofing membrane
- insulation
- layer of geotextile or other material with similar characteristics
- layer of crushed stone
- finishing coat
As you can see, the inversion roof is heavier than the traditional one and the insulation layer in it is located above the waterproofing layer. This roofing option is suitable for those buildings that have high fire safety requirements. And even despite the fact that the waterproofing layer on such roofs is usually made of flammable materials, those located underneath mineral wool slabs, act as a kind of barrier to fire. Thus, the roof structure is completely fireproof.
It is important that the installation of a flat roof - we mean insulation - is carried out taking into account the loads that may arise during operation. For example, for roofs in use, the thermal insulation layer must be thicker and stronger.
Installation of mineral wool slabs on a flat roof
The basis for the installation of basalt mineral wool slabs is either reinforced concrete structures, or metal profiled sheet. Regardless of what type of foundation the building has, a vapor barrier layer is first laid, which prevents water vapor from penetrating under the roof. If you skip this stage, then over time the mineral wool will accumulate moisture and cease to play the role of insulation, and the layer of waterproofing laid on top of it will “blister.”
For vapor barrier of a flat roof, either classic polyethylene or special weldable materials, such as bitumen and polymer bitumen, are usually used. The second option is more reliable and effective, since this vapor barrier has no seams and is very tear-resistant.
Important: the vapor barrier layer must be laid not only on horizontal surfaces, but also on vertical ones. You need to install the film or bitumen just above the level where the insulation will be located.
Laying mineral wool slabs
Insulation for flat roofs, in in this case basalt slabs are laid in one layer, but sometimes, if required by a pre-calculation of thickness, builders can enhance the thermal insulation with an additional layer of thinner, but no less durable, mineral wool slabs. Such a decision is made anyhow, but based on geographical location object, average temperature and humidity indicators in winter, as well as the purpose of the building.
Mineral wool boards are very light and laying them is not difficult. The main thing is to securely fasten the slabs
To attach the slabs to the base, either telescopic dowels or bitumen are used.
The first option is more logical to use when the base is a corrugated sheet, since it is best to fasten the slabs to the iron mechanically. In addition, fastening with dowels is much cheaper even if the slabs are installed on concrete. True, dowels for concrete are a little more expensive, and it takes longer to tinker with them.
With the mechanical method of fastening mineral wool slabs, the waterproofing layer is attached in exactly the same way, that is, on dowels. In this case, you don’t have to worry about the tightness of the roof, since the wide head of the dowel cannot pierce the waterproofing.
Important: if a mechanical method of fastening mineral wool slabs is chosen, then the vapor barrier layer must be made of fused materials, because only in this case the holes formed when driving dowels into the base will be able to tighten on their own.
Gluing onto bitumen is a rather labor-intensive and expensive process, and it is recommended when laying mineral wool on a concrete base. The technology in this case is as follows: a layer of bitumen is applied to the base, and a slab is laid on top of it. The procedure is repeated until the end of the roof. If there is a need to lay a second layer of insulation, then the first layer is coated with bitumen, and the slabs are mounted “in a staggered manner,” that is, in such a way that the slabs of the upper layer overlap the joints of the slabs of the lower layer. Waterproofing is laid on top of the mineral wool on the bitumen.
Which mineral wool boards are best used for flat roofing?
Not every type of mineral wool slab is suitable for flat roofing. It is important that the insulation has such strength that it can easily withstand both loads during operation and loads during installation, because builders will walk on it. You can make a screed over the insulation layer, which will distribute the load and create a rigid and durable base for the waterproofing floor. But whatever the screed is - dry from slate or asbestos or wet - it in any case significantly makes the roof structure heavier.
A way out of this situation can be high-strength mineral wool slabs from TechnoNikol, which are manufactured using a corrugator-pre-presser that lays fibers both horizontally and vertically.
Insulation of a flat roof with extruded polystyrene foam
Let's consider another option for insulating a flat roof, which is used for thermal insulation of inversion-type roofs.
Inversion roof insulation involves laying insulation on top of a waterproofing layer
Laying a waterproofing layer
The base of inversion roofs must have slight slope for water drainage and smooth surface. This can be done using a concrete screed. It is on this that the waterproofing membrane made of fused material is laid. It is installed in exactly the same way as in the case of a vapor barrier for a traditional roof, that is, with an approach to the vertical walls of the roof.
Installation of polystyrene foam boards
Expanded polystyrene boards are equipped with slot locks, however, to best protect them from moisture penetration, all joints must be treated with construction tape. The process of laying polystyrene foam is very simple, the main thing to remember is that the second layer (if necessary) must be installed in a staggered manner.
Expanded polystyrene boards are large enough and so that they are not damaged during installation, the reliable hands of an assistant are needed
Arrangement of the separating layer
The next layer will be geotextiles, which will protect the lower layers of the roof from mechanical damage and contamination. On top of the geotextile, a ballast backfill of gravel or crushed stone with a thickness of at least 5 cm is carried out, and for drainage, you can use a profiled membrane laid between the geotextile and the backfill.
Laying the finishing coating
As finishing coating paving slabs, asphalt concrete, foam concrete, and even lawn grass. In the latter case, it is necessary to lay another layer of geotextile on the crushed stone, and pour soil about 15-20 cm thick on top of it. Both perennial grasses and flower crops can be planted.
Insulating a flat roof is not an easy task, but if you complete it to perfection, you can be sure that the building will be warm and comfortable. True, for greater reliability it is also worth insulating the walls.
Thanks to the use of new heat and waterproofing materials, the once discredited flat roof has now found a new life. The fact is that despite the apparent simplicity of the design, its installation and subsequent operation have a lot of subtleties and nuances. Therefore, in order not to end up with a bunch of problems along with a roof over your head, you should get to know them better and try to avoid them.
The main difficulties include the difficulty of draining rain and melt water, the accumulation of snow in winter and falling leaves in autumn. In addition, bituminous materials, which are often used as waterproofing on such roofs, have a number of disadvantages. Their main flaw is that at negative temperatures, bitumen tends to shrink, which leads to cracking of the waterproofing layer in winter. Water leaks through the cracks that form and the coating begins to corrode. Therefore, the owners had to spend money on repairs every two to three years, which you will agree is not very pleasant and practical.
In general, there are several options for installing flat roofs:
Traditional
Inversion
Heated
Insulation of flat roofs using the classic method
The disadvantages that were listed above are mainly characteristic of the first type of roof - traditional. Insulation of a classic flat roof from the outside includes the following list of works. First of all, the insulated surface (1 - Fig. 1) is cleaned of debris and dust, and, if necessary, leveled (we’ll talk about the role of tilting a little later). At the next stage, thermal insulation is laid (2 - Fig. 1), it can be in the form of slabs, mats or rolled material. The insulation is usually attached to the concrete base of the floor using cold mastic or special glue. Depending on the region and the thermal conductivity coefficient of the material, the insulation is laid in one or several layers. In the latter case, to ensure thermal uniformity of the coating, the seams are positioned “in a staggered manner.” It is recommended to use rigid materials such as extruded polystyrene foam, foam glass or polyurethane foam as thermal insulation. Unlike fiber insulation, it provides stable thermal properties and dimensional geometry, high rigidity of the base under the roofing carpet, low weight of the coating and long term operation without roof repair, not less than the service life of the waterproofing.
The joints between laid slabs or mats are glued with construction tape; it prevents cement laitance from getting into them, which, when hardened, can serve as unnecessary cold bridges. With the thermal method of gluing the waterproofing sheet, a cement-sand screed is first applied to the thermal insulation (3 - Fig. 1), its height varies from 3 to 5 cm. To proceed to the next stage of roof insulation work, the concrete surface must gain strength.
The technology for laying the waterproofing layer (4 - Fig. 1), most often done using short-term exposure high temperatures for materials made on the basis of bitumen.
You can do this yourself, having the installation instructions at hand, gas burner and minimal skills to conduct such work. To ensure the reliability of the coating, waterproofing strips are glued to each other with an overlap of 10 cm, this is enough to ensure that the joints of the roofing carpet are strong and airtight. Finishing layer applied similarly to waterproofing. For this purpose, materials are used, sprinkled with stone chips on top, which protect the previous layers from mechanical damage and climatic influences.
It is necessary to pay attention to the fact that when using polystyrene foam, mineral wool or, for example, polystyrene foam as insulation, we will not be able to completely prevent moisture from entering the thermal insulation layer. Therefore, in such cases it is necessary to provide so-called vents (item 6, Fig. 2), builders call them fungi.
1 – vapor barrier; 2 – roof covering; 3 – internal drain; 4 – insulation; 5 – floor slab; 6 – vents;
They provide ventilation and help remove moisture from the roofing pie.
Inversion insulation of flat roofs
Another type of roofing that is currently becoming widespread is inversion roofs. Its structure and principle of operation follow from the name, translated from English “inversion” means reverse order anything. The most simple design such a roof is the following system, waterproofing, insulation and insulation are alternately laid on the floor slab concrete screed. Due to the fact that in this embodiment the waterproofing layer is located in a warm zone, it is not subject to the harmful effects of temperature changes, so the period
operation of such a roof is much higher. In addition, with a more complex structure of the roofing pie, this coating can serve as the basis for laying out lawns and flower beds.
Figure 3 shows one of the options.
1 – floor slab;
2 – waterproofing;
3 – insulation;
4 – drainage layer;
5 – weight (fine crushed stone)
6 – high-strength anti-root layer;
7 – lawn grass;
Leaning
Proper execution of the base allows you to significantly extend the life of the roofing carpet, as well as simplify its operation and repair. To ensure complete drainage of water, slopes are formed on the roof. The maximum service life is achieved with base slopes of at least 1.5% and a slope in the valley between the funnels. When these requirements are met, there are no areas for stagnant water on the base, and the roofing material functions optimally.
To eliminate the possibility of the roofing carpet breaking when transitioning to a vertical surface, install a transition side, a fillet at an angle of 450, measuring 100 x 100 mm (Fig. 4), from a sand-cement mixture.
Internal insulation of a flat roof
Insulation of flat roofs from the inside of the room, as a rule, is carried out with an already existing and operating structure, since this is a less effective method
heat preservation. But the most significant
minus this option is that the installation of the thermal insulation layer is carried out by reducing the height of the rooms, and this, as you understand, is not always aesthetically pleasing.
Installation from the inside of the building is quite simple and does not require special skills and knowledge; the only unpleasant thing can be called the inconvenience of carrying out the work. Before starting work, you will need to think through the room lighting system and provide output points for connection lighting fixtures. Then, retaining strips are nailed to the existing ceiling so that cells measuring 350 - 500 mm are formed. The height of the planks is selected depending on the thickness of the heat-insulating layer, which in turn is determined by the thermophysical properties of the material used and the calculated value of the required heat transfer resistance.
First, the bars are nailed along the perimeter of the room, then with the help of planks the rest of the space is divided into squares. Pre-cut thermal insulation material is inserted into the formed cells. Do not forget that when cutting soft insulation, it is necessary to provide mounting allowances of 10 - 15 mm, which will ensure installation of the workpiece by surprise. When using rigid materials, you will have to use temporary fastening to hold the insulation in the cells. This can be done 1 – roof covering; using short wooden planks or 2 holding strips; use the cord by pulling it “cross 3 – power structure; cross" along the top of the insulation in the cell. Also 4 – usable ceiling; you can resort to the gluing method, 5 – insulation; but not advisable. Temporary fastening 6 – vapor barrier layer; removed after filling the gaps 7 – finishing coating; between the thermal insulation material and the cell frame with polyurethane foam. When expanded, it will fix the insulation in the desired position. After this, you will need to deal with the electrical wiring system; to install it, use steel pipes, square or round section and brought to the required points. This work is performed after installing the thermal insulation layer. Don’t forget about the vapor barrier membrane, which will prevent moisture from getting inside the insulation. Otherwise, dampness will significantly reduce the service life of the insulation system. At the end, they are carried out Finishing work, installation of lighting fixtures and design of a new ceiling.
Insulation of any roof, including flat roofing, is considered in an effective way, which allows you to significantly reduce heat loss. Moreover, a significant effect is achieved with fairly modest heating costs. And this is not the only benefit that thermal insulation provides. But how to choose the right insulation for a flat roof and install it.
The nuances of insulating a flat roof
The principles of thermal insulation for a flat roof are fundamentally different from the approach to insulating pitched roofs. Flat design does not have rafters between which a thermal insulation layer could be placed. There is nothing to stuff the sheathing onto, so the formation of ventilation gaps for the components of the roofing pie, as in pitched roofs impossible. The analogy can be traced, perhaps, only in the order of layers. It consists of the following components:
- Vapor barrier. The layer is laid on the side of the premises and blocks the path of household fumes.
- Thermal insulation. This is a barrier to the passage of heat from inside the house to the outside and vice versa. At the same time, it plays the role of sound insulation.
- . It protects the thermal insulation layer from the outside from precipitation.
- Finish coating. For ballast roofs, the waterproofing layer is covered with gravel or laid on top of it paving slabs or a layer of soil under vegetation and more.
If the sequence of laying layers, as well as the rules of installation, are violated, deplorable complications arise that force owners to spend impressive sums for repair work, and sometimes for a major reconstruction of the roof.
However, it should be noted that the need for such a design arises only if it is necessary to ensure heating efficiency, that is, to retain heat in them. So when it comes to the roof summer kitchen or ancillary buildings, there is no point in insulating a flat roof.
In such cases, proceed, for example, as follows:
- in the concrete roofing pie there is only waterproofing:
- on corrugated sheets - prefabricated screed and waterproofing,
Classification of thermal insulation of flat roofs
- Attic. There are two subtypes of structures: attic floor with a low-weight superstructure or separate superstructure and ceiling structures. If in the first case only the ceiling is thermally insulated, then in the second - the ceiling or superstructure.
Attic structures can be easily inspected, which allows for timely identification of future leaks. Roofing pie can be dried by simply ventilating the attic. We especially note that insulation can be carried out on an already finished roof. The construction of an attic structure costs an impressive amount, but the long service life and rare need completely pay for it.
Insulation for flat roofs: technical nuances
To insulate a flat roof, use almost any material that is suitable for thermal insulation of the ceiling and walls. The following are especially in demand:
On a note
Wedge-shaped insulation cannot be considered as a worthy replacement for a layer of thermal insulation. Wedge-shaped slabs solve exclusively drainage issues.
Choosing a thermal insulation method
The method of insulation, as well as the characteristics of the required material, depends on the type of base:
- Reinforced concrete. The insulating material, most often mineral wool, is selected with a compressive strength of 40 kPa or more. The deformation parameters should not exceed 10%. A cement-sand reinforced or prefabricated screed is poured on top of the thermal insulation layer.
- Profiled sheeting. The insulation system has a two-layer structure. The lower tier with a strength indicator of 30 kPa or more is laid on top of the profiled sheet. For the upper tier, this parameter should not be less than 60 kPa. Possible deformation is within 10%. When installing a roof, the coating is laid directly on the insulation system.
The insulation must rest on the flat part of the corrugated sheet for at least 30% of its own area. Therefore, if the thickness of the thermal insulation board is twice the distance between the corrugations, the thermal insulation can be laid directly on the galvanized base. Otherwise, a preparatory leveling layer of CBPB slabs or flat slate is required.
How to lay insulation
- Placing rigid roof insulation on a flat roof begins from the low area of the roof, more precisely from its corner. If for some reason the slope of the structure when construction work was not observed, then you need to start from the installation sites of the gutter or.
- Thermal insulation boards are placed on the profiled sheets in such a way that the corrugations and their long sides are mutually perpendicular. In this case, fastening can be done through different ridges.
- Plates in multilayer thermal insulation are arranged according to the principle of brickwork, that is, the seams are staggered. In addition, the seam lines and crosshairs in the upper tier cannot coincide with those in the lower row.
Below is one of the options for cutting and laying insulation.
Mounting options
To fix the insulation layer on a flat roof, the following methods are used:
- Mechanical.
- Fastening is done using so-called telescopic fasteners. They consist of a flange with a smooth outer surface and a tubular rod. The various standard sizes of disc dowels available on the market allow you to fasten roofing pies of various thicknesses.
- IN concrete floors Anchors are hammered in and secured to the screed with screws with plastic sleeves.
- To calculate the required number of fasteners for an insulated flat roof, the default condition is taken as a basis: two units of fasteners for each slab.
- For concrete roofs, the coating and insulation are fixed simultaneously. If the base is made using profiled sheets, separately.
- In certain areas ( , interface lines with vertical planes etc.) the fastener installation step is reduced.
- Glue.
- All layers of the roofing cake, including thermal insulation, are glued to hot mastic, most often. The insulation must be glued evenly. At the same time, the total area of contact areas thermal insulation material with the base should exceed one third of it.
- If the roofing pie is completed with bitumen or bitumen-polymer material, then installation roofing system cannot be carried out during the rainy period, since excess moisture will accumulate in the insulation without being able to escape outside. But when used as a finishing coating, it can be glued throughout the year, since the membrane allows excess moisture accumulated in the insulation to pass through.
The insulation is laid on a flat roof and covered with a waterproofing carpet. A mixture of gravel and pebbles is poured over the waterproofing layer or paving slabs are laid on plastic supports. The components of the roofing pie lie freely. The pie is fixed exclusively around the perimeter, as well as around the roof penetrations.
Green roofs are also classified as ballast roofs. Although it should be noted that the roof with landscaping is inverse, so the order of the layers of the roofing cake differs from the traditional one. The insulation is laid on top of the waterproofing, which simultaneously functions as a vapor barrier. The thermal insulation layer is covered with a geodrainage polymer membrane, on which a soil-vegetative layer is arranged.
Installation of thermal insulation from the inside
Installing insulation slabs from the inside of a building with a flat roof is physically not very convenient, but practical. After all, installation can be carried out in almost any weather. And there is no need to rush to complete the work in a day, because the insulation does not get wet.
The algorithm for installing thermal insulation is as follows:
- Along the line where the ceiling meets the wall, screw a strip of wooden block, the thickness of which on one or both sides is equal to the thickness of the insulation.
- The same bar is attached on the opposite side.
- We screw a block, both or one of the sides of which is equal to the thickness of the insulation board, along the line where the ceiling and wall join.
- We install a similar bar made from a bar on the opposite wall.
- For internal insulation Rigid polystyrene foam boards are ideal.
- The ceiling is conventionally divided into strips.
- The polystyrene foam board is glued to the ceiling and plank using bitumen mastic and pressed tightly. The marked strip is completely filled with polystyrene foam. If necessary, the outer slabs are trimmed.
- Side of the completed strip of polystyrene foam boards, pressing tightly, screw another bar.
- Next, the insulation strip is formed and glued again.
- Alternating these two operations: screwing the bars and gluing the thermal insulation, fill the ceiling plane.
- Fixing them with a stapler, a plastic film is attached to the planks and the ceiling is finished with some convenient covering material, for example, plasterboard.
Which insulation for a flat roof is better to choose?
Expanded polystyrene gradesURSA XPS. The excellent quality of thermal insulation material produced by the international holding URALITA attracts many developers. It contains fire retardants, which increase the fire resistance of the insulation. This material is excellent for inversion thermal insulation. The slabs have cutouts on the sides that guarantee their perfect joining without the formation of gaps.
Extruded polystyrene foam Russian production It is produced in the form of slabs, along each side of which there is an L-shaped edge. It ensures perfectly smooth joining and continuity of the thermal insulation layer, which prevents the formation of cold bridges. Penoplex slabs do not absorb water, which means in this case you can do without additional protection from precipitation.
EPPS TechnoNIKOL. A few words about the products of the domestic company - TechnoNIKOL. The following types of materials are suitable for roof insulation:
- XPS CARBON ECO – insulation for roofs of low-rise or country houses.
- XPS CARBON ECO DRAIN – drainage grooves on the slabs help ventilate the flat roof.
- CARBON PROF is an especially rigid and durable polystyrene foam that can withstand enormous loads. Used in roofing pies of high-rise buildings, shops or warehouses.
- CARBON PROF SLOPE is no less durable than CARBON PROF, but this material has a special “trick”. It is supplied as a set of five slabs with different inclinations of the top plane. With their help they form.
TECHNORUF 45, 50, 60 and 70 are intended for installation of single-layer thermal insulation of flat roofs. The numbers in the markings indicate the compression density of the slabs. The thermal conductivity of the material is so low that these slabs can be used to insulate parking lot roofs.
TECHNORUF slabs are also used for two-layer thermal insulation: 50, 60, 70 for the top layer and 25, 30, 35, 40 for the bottom.
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