Water vapor spoils many building materials, making them unusable. Mold appears on the walls, destroying structures. Vapor barrier is an extremely important stage in the construction process, which cannot be dispensed with. There are many ways to protect walls from the aggressive effects of condensate. The use of a vapor barrier membrane is the most effective of them. In the photo, it looks like a roll, which is unwound, cut into pieces of the desired length in the process of working on the vapor barrier of the walls.

A universal, suitable insulating material does not exist. In the selection process, we take into account the properties of the object, the specificity of the existing design.

Brief content of the article:

The need for vapor barrier

High humidity, warm temperatures are ideal conditions for water vapor to appear, which, drawn by air, settle on wall coverings and ceilings. Constant humidity eventually leads to flaking of the plaster, destruction, molding of the walls.

Protection is especially relevant for rooms with temperature fluctuations, heated basements, baths, where water condenses constantly. Warm air, leaving the room, settles in the form of droplets on its walls and ceiling. Feels damp, may smell like mold.

Vapor barrier becomes an obstacle to the aggressive effects of water, protecting coatings from destruction. Not only basements, baths need it, but also many other buildings. Those that during the heated period are also prone to the formation of vapors, condensate for one reason or another.

When is a vapor barrier indispensable?

Used as a heater fiberglass or mineral wool. Well passing air currents, they are saturated with moisture over time, lose their heat-insulating properties, and collapse. High humidity is detrimental to them.

Effective vapor barrier in frame structures. Wall layering protection.

External protection of ventilated facades, walls from blowing. Excess moisture is removed through air exchange slots. It is especially important when the brick wall is insulated with mineral wool, and sheathed with siding on top.

Room ventilation is important. Together with thermal and vapor barrier, acceptable conditions are achieved to preserve the surfaces of the room — walls, ceiling from destruction, excessive aggressiveness of water.

Materials used

Laying vapor barrier is allowed using various materials. Full air circulation is not blocked. It is redirected to the hood. Prevention of the greenhouse effect, minimal airflow while retaining excess moisture — these are the most important tasks that can be solved by proper vapor barrier walls.

For protective work, the following materials are used:

polyethylene film. Fasten carefully, without pulling too hard. We do not create conditions for its damage. Polyethylene does not pass not only steam, but also air. Difficulty ventilating. A comfortable microclimate with this kind of protection is hardly achievable. Modern construction rarely uses it.

The use of mastic. Inexpensive, easy to use. Excellent breathability and moisture retention. Surfaces are processed prior to finishing works together with waterproofing works.

Membrane vapor barrier film. Modern way of protection. Provides normal air exchange of porous heaters. Does not allow their impregnation. It is used for insulation of frame, wooden walls. When the membrane film is stretched, it makes no sense to install air gaps.


When choosing vapor barrier materials, preference is given not to mastic, not to polyethylene. Priority first place in terms of expediency and efficiency is occupied by a membrane film.

It has a number of advantages that emphasize its profitability:

  • Achieves high efficiency in operation;
  • Installation is convenient, does not cause difficulties;
  • Repels moisture well
  • Provides surface resistance to the appearance, reproduction of mold;
  • It is resistant to decay;
  • The material is environmentally friendly;
  • Used for a long time;
  • Operates over a wide temperature range.

According to the features of the application, consumers widely use the following types of membrane films:

  • External insulation of wooden, frame, panel structures from rain, snow, wind using Megaizol A, Megaizol SD, Isospan A;
  • Protection of the inner surface (ceiling, walls) from steam, condensate with Izospan V, Megaizol V;
  • Reflection of steam, which is relevant for baths, saunas, using Isospan FX, Isospan FS, Isospan FD.

Membrane installation requirements:

  • The vapor barrier film adheres tightly to the insulation;
  • It has a reliable rigid fixation;
  • There are no sagging areas that create pops in gusts of wind.

Vapor barrier technology

Protection of internal walls is carried out after the use of insulating mineral materials that are prone to absorbing moisture during temperature changes.

The process of proper vapor barrier of walls with your own hands is carried out in the following order:

  • The membrane film is fixed with the right side on the crate. We work carefully, we exclude the risk of damage;
  • We glue cracks, joints, surface punctures with construction tape or special glue;
  • If we protect the frame structure, then we install a crate above the membrane to ensure ventilation;
  • We sheathe with any finishing material (drywall, panels, lining, etc.).

We protect frame structures: types of vapor barrier installation schemes

It is important to understand the correct steps in the process of laying the membrane, its real necessity. When foam, polyurethane foam, ecowool is used as a heater, a good ventilation system is installed, there is no need for vapor barrier of the walls.

The membrane is installed on the desired side and fixed to the racks with a construction stapler. The joints are glued with adhesive tape or glue, mastic.

There are two schemes for working with a vapor barrier film to protect the frame:

  • The crate is placed above the membrane (provides an air gap). It is used in houses with intensive use during the cold period;
  • An insulating film is sewn onto the frame racks, on top of which the finishing material is attached. When a seasonal stay, without heating is the best option. In this case, we think over the ventilation system well.

The intensity of the operation of the premises at different times of the year affects the choice of a particular installation scheme.

Wooden houses

High vapor permeability of walls is a distinctive feature of structures made of logs. Such houses need special protection. The walls already have natural moisture, in the process of five years of operation they dry out, deform, crack.

Given the specific vapor permeability, there are 2 ways to solve problems:

  • Wait until the wooden walls are completely dry to start finishing;
  • Use vapor barrier using the following types of membranes: Izospan FS, Izospan B, Izospan FB.

Thus, all work on vapor barrier is carried out depending on the characteristics of the structure, the intensity of its operation at different times of the year. At the same time, it is necessary that the membrane ideally repeat the contours along which it will be fixed. We work carefully, do not damage it. And then the problem with damage to external beauty does not threaten, the interior and facade design will last in perfect form for many years.

Photo of wall vapor barrier