Vapor barrier for the roof of the house

Any building structure is exposed to atmospheric precipitation that can destroy the performance of the building material. Currently, various modern thermal insulation materials are used in the construction of houses.

Moisture penetration is the main enemy of any roof. Vapor barrier and waterproofing helps prevent moisture from entering the insulation, which protect the structure, namely the roof, from moisture.

They are designed to protect the roof, namely the roof insulation, from the vagaries of the weather. These are two completely different materials that differ in their properties. There is no need to confuse them at all, since the insulation will be damaged and both protective layers, thus, you will have to redo the entire insulation structure.

Everyone knows that warm air rises up, accumulating at the ceiling, and cold air goes down. In order for the roof to be able to retain heat for a long time, insulation is used, which is located under the roof covering.

However, to get good thermal insulation, insulation alone is not enough. It is the insulation that is the place for the accumulation of water condensation, which appears due to the steam going up. And on top of the same insulation material moisture seeps out and also concentrates on the insulation. It turns out that protective coatings above and below are very necessary.

Accordingly, the vapor barrier prevents the penetration of humid air from the room into the insulation. Waterproofing does not allow accumulated moisture to penetrate inside the insulation. And it also turns out that the waterproofing passes the moist warm air outside, which passes through the vapor barrier layer. And the vapor barrier, in turn, does not release anything at all.

There are also differences between these materials in appearance. On the waterproofing material there are small holes for air passage, which are not on the vapor barrier film.

Why is it needed?

Vapor barrier - a very important element in the construction of any structure and structure.

If you think well and think about where the moisture comes from, and what the consequences are, it will immediately become clear how important the vapor barrier of the roof is during construction.

Warm air, saturated with vapors and accumulated near the ceiling, tends to escape. Accordingly, steam penetrates into the insulation and if the insulation is not protected, the insulation will begin to collapse.

The protection of the insulation is especially important in the winter. Steam that enters the insulation turns into frost at low temperatures, then into an ice crust. With the onset of heat, the ice melts and flows, while the insulation will lose all its necessary qualities and properties.

The main task of vapor barrier is to prevent the penetration of wet condensate into the insulation. Thus, preventing the appearance of dampness and mold, as well as the escape of heat from the room.

Vapor barrier is required in those parts of the building in which warm and cold spaces are delimited. These are, of course, surfaces inside the house, basements and roofs, as well as an attic. If the building is sheathed with natural wood material from the outside, it is not necessary to install a vapor barrier.

Materials (edit)

In modern times, a large selection of vapor barrier material is offered on the construction market.

The most demanded and used are film materials and membranes. Their vapor permeability is achieved by microperforation and using a special chemical composition.

Roof vapor barrier is mainly produced by three types of film materials:

Polyethylene films, with or without perforation

To provide strength, this type of film is used with additional fabric or mesh.Polyethylene films can be produced with the foil side, which is directed inside the room.

Polypropylene films

Much stronger than polyethylene.

Breathable films or membranes

They are one-sided, then they can fit on the insulation only with a certain side. In case of a double-sided membrane, laying can be done on either side. The material of the membranes is more in demand, in addition to the ability to pass water vapor, this material is not blown by the wind, and accordingly the loss of blown heat is reduced.

It is necessary to choose a material for vapor barrier of high quality, given that it will be located at the very base of the roof structure, therefore, it is difficult to access during repairs. The assortment of films is quite large, in different colors. Externally, different types of vapor barrier films are similar, but differ from each other primarily in different vapor permeability.

Among the many materials for vapor barrier, one should choose based on the climate conditions of the area where the house will be built, and also take into account the structure of a particular roof.

The vapor barrier material must be moisture resistant, meet all fire safety requirements, as well as environmentally friendly, i.e. it must not release harmful substances during operation.

Installation technology

The installation of the roof vapor barrier can be started after the installation of the thermal insulation, in any direction - horizontally or vertically. The film is attached to the inside of the insulation. It is important that a gap remains between the vapor barrier layer and the insulation, it will provide additional heat retention.

If the material used is a membrane, then it is attached directly to any insulation, from its inner side. Accordingly, there is no need to leave a ventilation gap. This allows the maximum amount of material to be used.

When installing vapor barrier material, you should adhere to several mandatory rules:

1. Firstly, do not put the film on the old roof. This will provoke the destruction of the roof.
2. Secondly, the material must be cleaned and dried.
3. Thirdly, the tightness of the vapor barrier material is very important. Any slightest violation of the tightness is unacceptable.

Step by step guide:

1. Laying the vapor barrier material yourself is quite simple. It is easy to install, comes in rolls, and is easy to cut. For fastening to wooden structures, you will need galvanized nails or staples that are driven in construction stapler, to a metal surface - double-sided or adhesive construction tape ribbon.
2. After the room is prepared, it is necessary to build a crate. You can use wooden planks or metal sheathing.
3. Then the laying of the vapor barrier begins directly. Roll sheets are attached to each other with a slight overlap.
4. In order for the seams not to allow moisture to pass through, they must be carefully glued, they must be tightly connected. For this, scotch tape is used.
5. Next, you should continue the interior decoration of the roof, covering the vapor barrier material.
6. Experts who know all the intricacies of installation and features of materials will help you quickly and efficiently produce vapor barrier.

Recommendations

The cost of a roof vapor barrier depends on the manufacturer of the material to be used. It is better not to save on material. Having bought quality material, but will serve you much longer.

Qualitatively and correctly performing the vapor barrier of the roof with high-quality materials, you will ensure the protection of the thermal insulation of the whole house. The vapor barrier will protect your home from moisture penetration and provide a long service life for the roof, then the house will be warm and dry at any time of the year.

Blitz Tips:

1. Before installing the vapor barrier, carefully examine the entire roof and insulation layer. If defects are found, do not leave them for later, repair them immediately.
2. When vaporizing window openings, do not forget to leave a reserve of film for sediment, about 20-30 cm.
3. The interior ceiling trim must not come into contact with the vapor barrier foil. To do this, it is better to attach bars that will fix the layer of thermal insulation and form an air space between the skin and the vapor barrier.