A vapor barrier is supposed to prevent moisture from entering our structure. What if we do not apply it?
The vapor barrier plays a key role in protecting the structure of our house from moisture. Its task is to prevent water vapor from the warm rooms from penetrating towards the colder layers of the building envelope. But what happens if we do not apply it?
What is a vapor barrier?
A vapor barrier is a tightly installed layer of foil in a wall, roof or floor. The vapor barrier film is meant to complement all thermal insulation, but it is also meant to prevent water vapor from penetrating the walls. This one occurs through temperature and pressure differences between the interior of the building and the outside environment. Where the vapor reaches colder layers, condensation can occur, leading to dampness in the structure. A vapor barrier stops this process, creating a barrier to moisture. This reduces the risk of fungus and mold on the walls, which are harmful to health.
Materials used for vapor barriers:
The most commonly used vapor barrier materials are:
- Vapor barrier films – Thin, flexible plastic films (such as polyethylene), which are a popular choice for single-family homes;
- Vapor barrier membranes – High-tech films with additional properties (e.g., self-adhesive or with reinforced structure);
- Vapor barrier membranes – used in more demanding constructions, such as flat roofs;
- Bitumen coatings – Used in waterproofing, such as in foundations.
Where is the vapor barrier used?
Roofs – A vapor barrier prevents moisture from penetrating the roof’s insulating layers (e.g., mineral wool), which is particularly important in pitched and flat roofs.
Walls – The use of a vapor barrier in exterior walls, especially in frame houses or lightweight buildings, protects the insulation from moisture.
Floors on the ground – A vapor barrier prevents moisture from the ground from penetrating the floor structure.
What if we don't use a vapor barrier?
In the absence of a vapor barrier, water vapor will begin to condense in the colder layers of the structure. Thermal insulation, such as mineral wool, is most often affected. Damp insulation loses its thermal insulation properties, resulting in a decrease in the energy efficiency of the building, but also an increase in heating costs. It is logical that damp wool or Styrofoam do not retain heat as effectively as dry materials.
As we have already mentioned, it is in the absence of a vapor barrier that we help the growth of mold and mildew. Moisture accumulated in the walls, floor or roof favors them, and this is not just an aesthetic problem, but also a health problem. Mold and fungi release toxins that can lead to allergies or respiratory problems.
Moisture that enters our structure can, over time, cause weakening, deformation or rotting processes. Looking at the long term, this reduces the strength, cracks can appear, and will eventually lead to the need for costly repairs.
Moisture that enters through the building envelope can also lead to problems with the facade. Through it, plaster and paint can fall off or finish materials can crack.
Don't take any chances
Proper application of vapor barrier protection, can exclude potential problems in the future. Appropriate – that’s the key word, because simply laying a vapor barrier without knowledge and experience can lead to leaks and the aforementioned negative consequences.
Don’t take risks, build your dream home with us!
