The roof is one of the main parts of the building's structural structure. The importance of its high-quality device is not only in protection from atmospheric precipitation, but, and this is the main thing, in the durability of all elements of the house.
Poorly executed waterproofing under the roof leads to the appearance of fungus on the rafters, walls and deterioration of the thermal characteristics of the house.
It is extremely important to soundly carry out the entire range of works on insulation from moisture, to prevent mistakes when the wrong film is used to waterproof the roof, the material is used in the wrong place or is covered with the wrong side. To be honest, such mistakes are often encountered not only in cases when roof waterproofing is done by hand, but also in the work of some "would-be builders".
Often such flaws arise as a result of mixing, combining the concepts of "vapor waterproofing", "waterproofing vapor barrier".
In order to avoid confusion, let's look at the materials used to waterproof the roof, exclude the accumulation of moisture in the under-roof space and the formation of condensation.
Note that waterproofing is cold roofs usually do not cause difficulties, since here it is only important to hermetically protect the wooden structures of the house from the roofing to be laid.
For this, completely impermeable films of increased thickness are used, ranging from ordinary roofing material to modern insulators Gidroizol, IzospanS, Tyvek and others.
With insulated roofing cake, the types of roof waterproofing are as follows:
For example, let's call IzospanV, an insulator with zero permeability.
From the names of the materials it is clear how different their properties are and, accordingly, the scope of application in construction work.
Also note that films of various types and purposes are produced within the same name. It is very important not to confuse them, to understand in which case and to a structural element and why the first or second insulation option is used. The correct use of insulating materials is the most important point, mistakes in their use will certainly lead to a lot of problems in operation, so we will dwell on this issue in more detail.
To understand where which film ( vapor barrier, vapor-permeable waterproofing or windproof) to use, we will make a short theoretical excursion. Everyone knows that moisture and steam are different states of water.
Steam is always present in the atmosphere, its accumulation in the thermal insulation layer has a detrimental effect on the fibrous porous material itself and on the wooden structures of walls, floors and roofs.
For our climate with many cool days and nights, it is usually cooler outside than indoors, and steam is known to move from warm to cold.
If only the insulation of the roof was uniform, and the steam freely passed through the roofing cake, then this would not be an obstacle for removing the vapors.
However, the insulated roof is not uniform and in a multi-layer roof structure it is important that steam does not accumulate inside the insulation. This will eliminate the possibility of condensation forming.
There would be no problem if each subsequent layer of the cake was more porous, more vapor permeable.
You ask, why not do this? The fact is that in practice it is rather difficult to create such a cake. Therefore, in construction work, it is more reliable to arrange complete insulation of the insulation from steam, to make it as tight as possible and to protect the roofing cake from external influences. To do this, consider how to make the roof waterproofing of high quality, ensuring long-term comfortable operation of the structure.
Important: Installation of vapor barrier is always carried out from the inside of the roof, preventing the penetration of moisture vapor from the premises of the house into the insulation.
For vapor barrier at the bottom the rafters are stuffed with a dry edged board of 20 * 100 mm or a bar with a step of about 50 mm. Along the crate without pulling! roll out the film, fixing it with staples of an ordinary stapler at a distance of about 5 cm from the edges.
This is for ease of use with double-sided self-adhesive tape. The next strips of insulator are overlapped by 10 cm.
All joints, cable passages, chimney, etc.
must be carefully glued with a special tape to ensure tightness. Believe me, it will cost much less than the subsequent opening of the roof and replacing the decayed insulation.
The industry produces insulation materials in rolls. Usually the side "facing" outward is indicated on the package, and the roll itself is made so that when it is rolled out, the front and back sides are in the right places. The modern market offers a large selection of materials for vapor barrier.
It is believed that the best waterproofing for a roof to prevent steam penetration is a foil sheeting that reflects to the room, although it is relatively expensive. In the west, conventional 200 polyethylene is mainly used as a vapor barrier.
Important : The vapor-insulated room must have good ventilation.
The vapor-permeable waterproofing of the roof is always performed from the outside of the rafters, and when doing work with your own hands, you should pay attention to the manufacturer's instructions, which regulates how to fix the waterproofing on the roof (with a gap from the insulation or without). In any case, the film is rolled out without stretching, with a slight slack.
Installation of roof waterproofing is carried out along the rafters, with the vapor-permeable side to the insulation, waterproofing - outward, with an overlap of 10 centimeters and sealing the joints with self-adhesive tape.
Insulation protects the insulation from possible moisture ingress and blowing. By the way, hence the second name of the film - wind protection. The high-quality tightness of the waterproofing also contributes to a significant increase in the thermal insulation characteristics of the roofing cake. To ensure ventilation of the under-roof space along the rafters, a runaway bar of 40 * 50 or 50 * 50 mm is packed over the film.
Then, depending on the type of roofing, a step crate is arranged (for metal tiles, profiled sheets, ondulin, etc.) or a continuous slab flooring (for a soft roof).
In a well-made waterproofing, the film covers the rafters of the gables, roof overhangs and tightly borders the chimney outlets.
It does not matter whether the roof is waterproofed with your own hands or with the involvement of builders, this type of hidden construction work requires special attention and conscientious execution.
Therefore, concluding the review, we would like to summarize some recommendations:
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