How to insulate the roof so that it meets the technical conditions?
Let’s focus on the selection of appropriate materials
How to insulate the roof properly?
Diligence in performing insulation works is a priority
The purpose of insulating our roof is to improve its thermal and acoustic properties. We insulate it with the hope that the costs we incur during the work will be compensated by lower electricity bills. However, let’s make sure that the works are carried out in accordance with the current requirements of the construction law, and that the selected materials for roof insulation are of good quality. A reasonable price and proven manufacturers of the necessary materials as well as qualified professionals are the factors that will positively affect the effect of our activities. How to insulate the roof? What insulation materials will we need to achieve the intended effect? Let us remember that according to the amendment to the construction law, from 2021 we can build houses only taking into account the aspect of energy efficiency.
As we know, warm air rises, so properly insulating the roof is a priority in terms of energy savings. What’s more, the heat transfer coefficient on a horizontal surface is much higher than on vertical surfaces. When it comes to technical requirements, the energy transfer coefficient of the roof is much more demanding compared to the subfloor and external walls. Concerned about professional insulation, manufacturers of building materials distribute to DIY stores more and more effective means for insulation works. Among the thermal insulation materials, we can mention: mineral wool (glass or rock), polystyrene, spray foam, thermal insulation boards or extruded polystyrene (styrodur). Each of the insulation materials listed above has a different thermal conductivity coefficient. The best in this respect turns out to be mineral wool and polystyrene. Polystyrene and thermal insulation boards fare much worse in this context.
If we have mineral wool at our disposal, our task is to lay it in two layers. The point is to thoroughly insulate the elements between the rafters and those under them. In the case of a pitched roof, thermal insulation is also installed between the above-mentioned rafters and also under them. What about high attics? In their case, we can cut off the space that we do not use and make a ceiling under it. Then we perform thermal insulation traditionally, e.g. by insulating with mineral wool. If the layer we make turns out to be sufficient, we can omit the insulation of the top of the building. If the roof structure consists of truss trusses, the insulating material is placed in the band of trusses: upper and lower. The situation is different in the case of flat roofs. Here, we should lay the insulation layer on the structure and implement waterproofing. The upper part of the thermal insulation should be made of a hard material, for example a roof board. When installing such a board, we can be sure that it will be resistant to pressure. In the case of an unused attic, the insulation layer should be placed directly on the ceiling. Then it will be a partition for insulated and non-insulated rooms.
In addition to well-chosen insulation materials, the care of their installation is a factor that affects the quality of thermal insulation. Therefore, we should ensure that the insulation of our roof is continuous and accurate. Thermal insulation should fill the entire surface under the roof. For example, a layer of mineral wool should be laid smoothly and ensure its connection with the insulating layer that we put on the façade. What’s more, structural elements such as: roof windows, rafters, wall panels should be properly insulated. If necessary, you can also make a second layer of thermal insulation. The tightness of the roof also plays an important role. Therefore, we should diversify the layer of wool with a vapor barrier. In this way, we will reduce the risk of possible moisture penetration to a minimum. It is worth knowing that damp wool has definitely worse insulating parameters, and – as we know – moisture favors the formation of mold. We meticulously combine the vapor barrier sheet with wool and construction elements, and we will be able to enjoy energy savings for a long time. Thus, the costs incurred as a result of the work will be effectively amortized.