Vapor barrier for roof: materials, mounting, instruction

Vapor barrier for roof: materials, mounting, instruction

It is quite often possible to hear about need of making of vapor barrier. At the same time this layer of roofing pie is required not always. Let's consider what its assignment, what materials are used and also nuances of mounting.

It is quite often possible to hear about need of making of vapor barrier. At the same time this layer of roofing pie is required not always. 

For what the vapor barrier of roof is necessary?

Air in the house it is frequent more warmly, than on the street. Because of temperature difference condensate which accumulates under roofing covering is formed. Because of it heater, wooden overlappings and furring begin to decay, there is mold growth. All this affects quality and durability of roof of the building.

It is important not to confuse vapor barrier with waterproofing. The first protects from internal condensate and the increased air humidity indoors, doing not miss couple, the second – from atmospheric precipitation.

Thus, the vapor barrier allows to protect the materials, the most subject to negative impact of moisture. It is laid by separate layer of roofing pie or heat-insulating material can have this property.

Materials for vapor barrier

The most widespread and inexpensive material for vapor barrier – ordinary polyethylene film, but it does not render absolute protection. The film meets armoring lattice. It has no impact on vapor permeability, but significantly increases the estimate therefore experienced builders do not recommend to use reinforced film for vapor barrier of roof.

In the market it is possible to meet anti-condensate film. It is the same polyethylene having from the inside special fleecy layer of fabric which is absorbed moisture. Externally film on the one hand smooth, with another – rough. When mounting material fix to heater the smooth party.

Excellent is in demand izospan, made of polypropylene cloth. Inexpensive material, is easily mounted, has the long term of expluattion, is at the same time used also for waterproofing. Izospan is widely applied in construction, has several versions, depending on assignment. Universal meet. Availability of the folginirovanny party strengthens roof thermal insulation. Therefore before purchase it is important to specify technical characteristics whether it is suitable for roof.

More modern material for parobaryer – membranes. It is nonwoven polypropylene with plastic film. Membranes perfectly pass steam, but not moisture. When mounting such material the ventilating gap is surely left.

Mounting of vapor barrier of roof

It is better to combine mounting of vapor barrier with process of warming of roof. The film always keeps within on heater. At horizontal mounting (it is peppered to rafters) the film keeps within from top to down with an overlap 10-15 cm. Further the film is fixed by the construction stapler and special tape. At vertical mounting the joints of films have to fall on furring. Otherwise the film can tear despite fixing by tape. In cases of roof of mansard type in places of joint film with window openings special aprons or tape are used.

Joints are recommended to be fixed bars as furring. Thickness of bars - from 25 to 50 mm. It is obligatory to fix places of punctures of self-tapping screws adhesive tape with aluminum covering. It will protect vapor barrier from holes and tears which will freely pass water vapor.

Pulling film, it is important to avoid sagging. In general mounting of vapor barrier is simple, though demands some skill.

Author: «MirrorInfo» Dream Team