Properly organized insulation in the house is the key to comfortable living conditions. If the main floors and wall structures do not have high heat-saving properties, then the functions of providing a favorable microclimate are shifted to insulating materials. The most effective solution to this problem is the insulation of the roof along the rafters, a photo of how this process takes place is presented in the article.
The nuances of choosing a material for insulation
The material for insulation in the rafter area is usually selected taking into account the heat-insulating potential of the structure, but this is far from the only selection criterion. The supporting structure for slopes has fundamentally important limitations in terms of additional arrangement. The main one is the weight load, so the material must be light and small-sized, since the fixing devices in the case of large-format panels are alsoprovide extra mass.
As for the form factor, subject to structural compatibility, experts recommend using tiled, rolled products. An exception applies only to backfill materials that are appropriate to use on the floor of the attic or attic. It is advisable to carry out roof insulation along the rafters from the inside in thin layers, with the expectation of the possibility of a device and a protective coating. In this case, it will be better to use products with the presence of external metallized layers that provide a barrier to mechanical stress.
In addition, you should follow the general rules for choosing materials for arranging the roof and roofing system. It is important that the insulator is non-flammable and biologically stable. The truss system formed by sawn wood, in itself, without protective impregnations, is vulnerable to the development of fungus and mold, not to mention supporting the flame. In this sense, the internal insulating coating should become a barrier to the negative factors of the possible destruction of beams and support posts.
Don't forget waterproofing
According to experts, moisturizing the insulating material by only 1% can reduce its thermal conductivity by up to 30%. In the winter season, this percentage rises and can cause destruction of the insulator structure. Therefore, the technology of roof insulation along the rafters without fail provides for the inclusion of a hydrobarrier in the insulating structure. It is desirable that the moisture-resistant shell also combines the qualitiesvapor barrier.
Hydrological insulation materials are mainly evaluated in terms of strength, abrasion resistance and fire resistance. These are mainly artificial products, so biological threats are excluded. The optimal solution may be a roofing membrane based on polypropylene or polyethylene. If you apply a modification of the film with a reinforcing fabric or mesh, then the roof insulation along the rafters can be performed without a special counter-lattice from the outside. The diffusion membrane is recommended to be laid directly on the heat insulator layer, which will reduce the amount of work and costs. This waterproofer directs moisture in one direction - from the surface of the insulation. Also, condensate collects on the reverse side, after which it drains or erodes. An important nuance when arranging the layers of the waterproofing agent is to lay them with the right side to the insulation. Usually the same membranes are marked with special inscriptions indicating the front or back side.
What should be the structure of the insulating "pie"?
Insulation placement configurations in a roofing system can vary depending on roof characteristics, insulation requirements, and rafter pattern. In any case, the outer layer will be represented by the roofing material - it can be a metal profiled sheet, bituminous tiles or slate based on asbestos concrete. This coating can also be fixed to the rafters, however, intermediate rails are most often used to make the joint secure. A kind of crate is formed, with which it is already mated on the insideheat insulator. But before that comes the outer isolation. Among the subtleties of roof insulation along the rafters, the importance of maintaining ventilated gaps should be noted. That is, 2-3 cm should remain between the conditional mineral wool slabs and the roofing for air circulation. It is this indentation that the laths of the crate will provide.
Additionally, before thermal insulation from the outside, vapor barrier and wind protection can follow. The presence of the last layer just depends on the type of roof. For example, modern models of shingles and ondulin take on some of the insulating functions, eliminating the need for lining additional technical layers. From the side of the attic, the technology of roof insulation along the rafters also provides for the inclusion of hydro- and vapor barrier films, which, depending on their own structure, can be covered with a crate with subsequent cladding or remain open. For all its impracticality, the second option can be justified by the fact that the owner can always assess the state of insulation during an external examination. And, on the contrary, under the lining layer, the resulting defects will be hidden, due to which dampness may appear.
How to properly insulate between rafters?
The most common insulation scheme is one in which thick slabs can be used. Moreover, the size of the segments is selected so that the width is 10-15 cm larger than the gaps between the rafters. This distance will be used as the cells of the crate, inwhich, according to the classical system, lay a heat insulator. The width tolerance is necessary for tight integration of the insulation into free niches without gaps. As for the thickness, it is selected to decrease relative to the protrusion of the rafter legs. This condition is necessary to save space for the same waterproofing or other technological and protective coatings. Proper roof insulation along the rafters is carried out in such a way that a dense and even base is formed from the insulation material in the structure of the load-bearing beams. To do this, it is necessary that the laying surface also has the correct geometry, and this will again depend on the characteristics of the roof.
The subtleties of thermal insulation under the rafters
Filling the free space between the rafter legs is a simple and practical option for warming. Thus, additional rigidity is given to the supporting structure, the structure of the insulating material placement receives the necessary holding elements, and niches are filled in which cold air can “walk”. However, this option is not always possible due to the following reasons:
- Laying communications in the space between the rafters.
- Insufficient structural rigidity to accommodate additional materials.
- Using an insulator, which in principle cannot be laid into the grooves.
In such situations, you can apply an alternative layout of the heat insulator on the back side. But even in this case, there are structural nuances of roof insulation along the rafters, which consist in the problems of removing the insulating layer.beyond the level of the supporting structure. In this case, the niches between the rafter legs are covered with solid material (plywood, chipboard, etc.), and a heater is laid on it. Thick slabs in this configuration are impractical to use, since an additional superstructure is required, which will significantly increase the load and reduce free space in the attic. But it is allowed to use thin rolled material, for fixing which, together with waterproofing, there will be enough rails and a protective reinforced film.
Insulation technology over rafters
Reverse to the previous technique, the scheme of laying the heat insulator is one in which the material is located not on the back side, but on the outside - between the roofing and its supporting structure. But this method also involves the observance of certain structural conditions, the main among which is the design preservation of space for the organization of roof insulation along the rafters. Laying in this case is carried out on top of the truss structure with a superstructure in the form of a crate. In preparation for installation, it is necessary to cover the load-bearing beams with sheet wood-chip panels. Lathing ribs are mounted on a flat surface, between which (a distance of about 50-60 cm) an insulator will be laid.
The upper part of the material is also covered with waterproofing and other technological coatings depending on specific requirements. There are two options for an external closing coating. In the first case, roof insulation overthe rafters are left unfinished. That is, in relation to the back side of the roof, the same waterproofing remains open. This option is good because it leaves a free zone for air ventilation - in the place of interaction of insulators and roofing material there are surfaces that are resistant to negative humidity and biological factors. The second option involves the installation of a small-format crate with intermediate power rails, along which the roof will be laid. This scheme is good precisely for the additional mechanical and wind protection of the insulators, but in this case the ventilation effect of the under-roof space is reduced and the wood finish of the insulation remains less protected from contact with moisture.
Combined insulation scheme as the best option
In this case, a comprehensive thermal insulation of the roof structure is implemented in three directions. That is, the roof will be insulated over the rafters, between the beams and above them. It is immediately worth noting a few nuances of using this configuration, since it has many features:
- The load on the truss structure increases.
- Requires more technology space inside and out relative to ramps.
- The technical arrangement of the roof becomes more complicated, since several levels of insulation will require the organization of additional mounting systems.
- The possibility of laying communications in the roof niche is excluded.
- Financial costs of material are rising.
This scheme is inappropriate for small houses. Moreover, it is usually used in full-fledged attic rooms, where, in principle, a more solid roof structure is provided and there is enough space for the installation of complex technological elements. On the other hand, it is the combined technology of laying roof insulation along the rafters that makes it possible to turn the attic into a living space for the winter period. Even at the design stage of the roof, it is necessary to provide for the possibility of installing three levels of insulation. Technically, the installation of this design is implemented under the following conditions:
- Two crates are organized from the inside and outside in relation to the truss structure. That is, beams for rafter legs are initially selected with large sizes, preferably with metal reinforcing plates.
- Provision is made for the inclusion of supporting vertical posts to hold not only the truss structure, but also the insulation. To evenly distribute the load of the supporting area at the level of roof insulation, metal sheets or chipboard panels with grooves for fixing racks are mounted along the rafters from the inside.
- As each new layer of insulation is laid with panels closing the next crate, it is necessary to make technological holes for the future passage of ventilation and chimney pipes. In a fully closed formed insulation structure, this operation at all levels will be difficult to perform.
Mounting methods and arrangement of insulators - what to consider?
Basicallytwo methods of installing thermal insulation materials are used: adhesive and mechanical (using hardware). Each of them has its own nuances of application, so they should be considered in more detail:
- Adhesive fastening method. If you plan to perform roof insulation along the rafters with your own hands, this method will be preferable. To implement it, it is enough to clean the laying surface in the form of the same plywood sheet or the back side of the roof, apply the adhesive mixture and fix the insulator. This technique is used for both roll and tile insulation, but in both cases it is necessary to choose the right composition. For self-laying, beginners are advised to use ready-made dry mixes. More experienced roofers use two-component products that can be further modified to improve certain performance. For both cases, it is recommended to use products from Ceresit, Soudabond and Insta.
- Installation with mechanical fasteners. The complexity of this method lies in the fact that the rafter system is not the most successful base for installing hardware. By the way, the unsuccessful introduction of a large-format dowel into a weak beam can cause future decay of its structure or the spread of cracks. How to properly insulate the roof along the rafters in order to avoid such phenomena? Firstly, large-sized nails, anchors and dowels should be abandoned in principle. The emphasis is not on force capture (as a rule, heaters have a small mass and do not require rigid fixation), but on holding indesired position. To do this, it is enough to use umbrella thin dowels. In the case of rolled materials, you can completely limit yourself to mounting brackets by installing them with a construction stapler. Secondly, the installation points, together with the fasteners, are pre-treated with antiseptic and other bioprotective solutions for wood, which will prevent the processes of decay, mold and fungus inside the structure.
Features of roof insulation on rafters with mineral wool
This is the most famous material for thermal insulation. Despite certain disadvantages, such as extremely low protection from moisture, mineral wool is readily used in roofing. This material can perform both partial and complete insulation of the roof structure. It is advisable to use plates with a thickness of 20 cm (minimum) if we are talking about a region with a cold winter. If there are structural restrictions on the thickness, then the thickness is reduced to 10-15 cm. By the way, the same rules apply when the roof is insulated along the rafters with foam, but with one fundamental difference. Styrofoam, with all its advantages as a heat insulator, has a drawback associated with unsatisfactory soundproofing qualities. Therefore, in addition to auxiliary technical layers of insulation, it may be necessary to additionally lay noise-reducing material.
As for installation, it is necessary to note the nuances of observing safety precautions with such insulation of the roof along the rafters. How to properly install mineral wool? Only in sealedgloves, respirator and goggles, as this material releases toxic substances. Technically, laying is carried out according to the general scheme on the crate with a mandatory coating with a waterproofing agent, but it is also recommended to additionally apply thin retaining rails along the central parts of the slabs.
Features of the use of foam insulation
This is a rather specific material in terms of thermal insulation of the roof, it is rarely used as such, but with proper installation, such a move is possible. Foam insulation is usually understood as polyurethane foam, the qualities of which determine the non-standard nature of this kind of insulation. To begin with, it is worth considering how it is beneficial to insulate the roof along the rafters based on a foam composition? This is the best option in terms of design. Spraying polyurethane foam allows you to lay the material in different configurations, regardless of the complexity of the site, the foam will take any shape. In addition, this is the lightest heat insulator, so you do not have to be afraid of excessive weighting of the truss system.
However, there are severe restrictions on the use of polyurethane foam on the roof. This material supports combustion (at least slowly smolders, also releasing toxic substances), does not combine with metal sheet roofing (excessive condensation and minimization of the ventilation gap) and cannot be used in places where exposure to high temperatures is expected (if the roof is heated strongly from the sun, destruction will occur material). But does this mean that from the insulation of the roof along the rafters with the help ofpolyurethane foam should be abandoned? Not at all, since its negative properties are not of particular importance when puncturing the so-called cold bridges. That is, the foam insulator can be applied zonally as an addition to the main heaters.
Conclusion
When deciding on the choice of roof insulation technology, it will not be superfluous to turn to special offers from thermal insulation manufacturers. Large firms meet the needs of the consumer, trying to facilitate installation tasks when using their products. For example, the insulation of the roof along the rafters with Penoplex is distinguished by the use of a tongue-and-groove locking edge, which completely eliminates the issue of choosing a fastener technique and minimizes gaps at the joints. In turn, the Knauf company offers special solutions for pitched roofs. This is a roll material that is easy to cut, takes the desired shape of the laying and does not require further protection with a waterproofing agent, since its structure contains Aqua Statik proprietary water-repellent impregnation. No less interesting options for insulation for a variety of operating conditions are also offered by the manufacturers Izover, TechnoNIKOL, Ursa, etc.
