Properly organized insulation in the house is the key to comfortable living conditions. If the main floors and wall structures do not differ in high heat-saving properties, the functions of ensuring a favorable microclimate are transferred to insulating materials. The most effective solution to this problem is to insulate the roof along the rafters, photos of how this process occurs are presented in the article.
Nuances of the choice of material for insulation
Material for insulation in the rafters 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 from the point of view of additional arrangement. The main one is the weight load, so the material should be light and small-sized, since the fixing devices in the case of the use of large-format panels will also provide additional weight.
As for the form factor, subject to structural compatibility, experts recommend the use of tiled, rolled products. The exception applies only to bulk materials, which are appropriate to use on the ceiling of the attic or attic. It is advisable to carry out insulation of the roof 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 adhere to the general rules for the selection of materials for the arrangement of the roof and roofing system. It is important that the insulator is non-combustible and biologically stable. The rafter system, formed by wood lumber, in itself without protective impregnation is vulnerable to the development of fungus and mold, not to mention the support of the flame. In this sense, the internal insulation coating should become an obstacle to the negative factors of the possible destruction of the beams and support pillars.
Do not forget about waterproofing
According to experts, moistening the insulation material by only 1% can reduce its thermal conductivity to 30%. In the winter season, this percentage increases and can cause damage to the structure of the insulator. Therefore, the technologies of roof insulation along the rafters necessarily include the inclusion of a hydrobarrier in the insulating structure. It is desirable that the moisture-resistant casing also combines the qualities of a vapor barrier.
Materials of hydrological isolation are mainly evaluated by the parameters of strength, abrasion resistance and fire resistance. These are mainly artificial products, therefore biological threats are excluded. The optimal solution may be a subroof 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. It is recommended to lay the diffusion membrane directly on the heat insulator layer, which will reduce the amount of work and costs. This hydroinsulator directs moisture in one direction - from the surface of the insulation. Condensate also collects on the back, after which it drains or erodes. An important nuance in the arrangement of the waterproofing layers is to lay them with their 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”?
The configuration of the insulation in the roof system can be different depending on the characteristics of the roof, the requirements for insulation and the rafter scheme. In any case, the outer layer will be represented by the roofing material - it can be a metal professional sheet, bituminous tile 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 reliable. A kind of crate is formed, with which a heat insulator mates already on the inside. But before this comes external isolation. Among the intricacies of roof insulation along the rafters, it is worth noting the importance of maintaining ventilated gaps. That is, between conditional mineral wool slabs and the roofing should remain 2-3 cm for air circulation. It is this indentation that the battens will provide.
Additionally, vapor barrier and wind protection can follow on the outside before thermal insulation. The presence of the last layer just depends on the type of roof. For example, modern models of bituminous tiles and ondulin take on some of the insulation functions, eliminating the need for additional technical layers. From 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 followed by 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 isolation during an external examination. And, on the contrary, under the layer of the lining the formed defects will be hidden, due to which dampness may appear.
How to properly isolate between rafters?
The most common insulation scheme is one in which thick boards can be used. Moreover, the size of the segments is selected so that the width is 10-15 cm greater than the gaps between the rafters. This distance will be used as the cells of the crate, in which the heat insulator is laid according to the classical system. The width tolerance is necessary for tight integration of the insulation into free niches without gaps. As for the thickness, it is selected for lowering 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. The correct insulation of the roof along the rafters is carried out so that a dense and even base is formed from the insulation material in the structure of the bearing bars. To do this, it is necessary that the surface for laying had the correct geometry, and this will again depend on the characteristics of the roof.
Subtleties of thermal insulation under the rafters
Filling the free space between the rafters is a simple and practical option for warming. Thus, additional rigidity is given to the supporting structure, the placement structure of the insulating material receives the necessary holding elements, and niches are filled in which cold air can “walk”. However, this option is not always possible for the following reasons:
- Laying communications in the space between the rafters.
- Insufficient structural rigidity to accommodate additional materials.
- The use of an insulator, which in principle cannot be laid in grooves.
In such situations, you can apply an alternative layout of the heat insulator on the back side. But in this case, there are structural nuances of roof insulation along the rafters, which are the problems of removing the insulating layer beyond the level of the supporting structure. The niches between the rafters in this case are closed with solid material (plywood, chipboard, etc.), and a heater is laid on it. It is impractical to use thick slabs in this configuration, 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 roll material, for fastening which, together with waterproofing, there will be enough battens and a protective reinforced film.
Technology of insulation over rafters
The scheme of laying the heat insulator, which is inverse to the previous technology, is one in which the material is not located on the back side, but outside - between the roofing and its supporting structure. But this method also requires compliance with some structural conditions, the main among which is the design conservation of space for the organization of roof insulation along the rafters. Laying in this case is carried out on top of the rafter structure with a superstructure in the form of a crate. In preparation for installation, it is necessary to close the load-bearing beams with sheet chipboards. The edges of the crate are mounted on a flat surface, between which (the distance is about 50-60 cm) and the insulator will be laid.
The upper part of the material is also covered with waterproofing and other technological coatings, depending on the specific requirements. There can be two options for an external closing coating. In the first case, the insulation of the roof over the rafters is left without finishing. 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 because of 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 in three directions is implemented. That is, the roof will be insulated over the rafters, between the beams and above them. Immediately it is worth noting several nuances of using this configuration, since it has many features:
- The load on the rafter structure increases.
- More technological space is required inside and out relative to the ramps.
- The technical structure of the roof is becoming more complicated, since several levels of insulation will require the organization of additional installation systems.
- It excludes the possibility of laying communications in the under-roof niche.
- Increased financial costs for the material.
This scheme is impractical to apply in small houses. Moreover, it is usually used in high-grade attic rooms, where, in principle, a more thorough 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 the roof insulation along the rafters that makes it possible to make a living room out of the attic for the winter period. Even at the stage of designing the roof, it is necessary to provide for the possibility of three levels of insulation. Technically, the installation of this design is implemented under the following conditions:
- Two crates are arranged inside and outside with respect to the rafter structure. That is, the rafters for rafters are initially selected with large sizes, preferably with metal reinforcing plates.
- It is envisaged to include supporting vertical racks to hold not only the rafter structure, but also the insulation. To evenly distribute the load of the supporting area at the level of roof insulation along the rafters, metal sheets or wood-shaving panels with grooves for fixing the racks are mounted from the inside.
- As each new insulation layer 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 enclosed formed insulation structure, this operation at all levels will be difficult to perform.
Mounting methods and device insulators - what to consider?
Basically, two methods are used to install thermal insulation materials: adhesive and mechanical (through hardware). Each of them has its own nuances of application, so they should be considered in more detail:
- Glue method of fastening. If you plan to perform roof insulation on the rafters with your own hands, this method will be preferable. For its implementation, it is enough to clean the laying surface in the form of the same plywood sheet or the back 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. When self-laying, beginners are recommended to use ready-made dry mixes. More experienced roofers use two-component products that can be further modified in order to improve one or another 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 propagation of cracks. How to properly insulate the roof along the rafters to avoid such phenomena? First, in principle, large nails, anchors and dowels should be discarded. The emphasis is not on power gripping (as a rule, heaters have a small mass and do not require rigid fixation), but on holding in the right position. For this, it is enough to use umbrella thin dowels. In the case of rolled materials, you can completely limit yourself to mounting brackets, 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, the development of mold and fungus inside the structure.
Features of roof insulation on rafters mineral wool
This is the most famous material for thermal insulation. Despite certain disadvantages, such as extremely low moisture protection, mineral wool is readily used in the arrangement of roofs. With this material, you can perform both partial and complete insulation of the roof structure. It is advisable to use plates with a thickness of 20 cm (minimum) when it comes to 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, these same rules apply when insulating the roof with rafters with foam, but with one fundamental difference. The foam, with all its advantages as a heat insulator, has a drawback associated with unsatisfactory soundproofing qualities. Therefore, in addition to auxiliary technical insulation layers, laying of noise-canceling material may additionally be required.
As for the installation, it is necessary to note the nuances of observing safety precautions with such insulation of the roof along the rafters. How to properly lay the mineral wool? Only in airtight gloves, a respirator and construction glasses, as this material emits toxic substances. Technically, laying is carried out according to the general scheme on the crate with a mandatory waterproofing coating, but it is also recommended that thin retaining rails be applied to the central parts of the plate placement.
Features of the use of foamed insulation
This is quite specific material from the point of view of thermal insulation of the roof, in this quality it is used infrequently, 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 what is the benefit of roof insulation on rafters based on foam composition? This is the best option in terms of construction. Spraying polyurethane foam allows you to lay the material in different configurations, regardless of the complexity of the site, the foam will take any form. In addition, it is the lightest heat insulator, so you do not have to be afraid of over-weighting the rafter system.
However, there are strict restrictions on the use of polyurethane foam on the roof. ( , ), ( ) , ( ). , ? , . .
Conclusion
Determining the choice of roof insulation technique, it will not be out of place to turn to special offers from manufacturers of thermal insulation. Large companies are moving towards the consumer, trying to facilitate installation tasks when using their products. For example, the roof insulation along rafters “Penoplex” is distinguished by the use of the “tongue-groove” locking edge, which completely eliminates the issue of choosing the fastening technique and minimizes the gaps in the joints. In turn, the Knauf company offers special solutions for pitched roofs. This is a rolled material that is easy to cut, takes the desired form of laying and does not require further protection with a waterproof insulator, since its structure contains Aqua Statik's proprietary water-repellent impregnation. No less interesting insulation options for a wide variety of operating conditions are also offered by the manufacturers "Izover", "Technonikol", "Ursa", etc.