When you are buying wallcovering, you probably already know to look for certain things like how easy the wallpaper is to clean or how long you can expect it to last. You probably aren’t even aware of what a permeability rating is, let alone why it is important.
What Is the Permeability Rating?
The permeability rating is a measurement of how easily water vapor can permeate the wallcovering. While this may seem unimportant at first, a wallcoverings permeability rating can have a lot of long-term implications. The lower the permeability rating, the harder it is for water to pass through the wallcovering. This can result in mold and mildew forming both on the back of the wallcovering and in the walls.
What Are the Ratings?
There are three rating classifications for permeability.
- Class 1 – A wallcovering with a permeability rating under 0.1 – this indicates that water vapor will not be able to easily permeate the wallcovering, causing a high risk of mold and mildew issues. The wallcovering acts as a barrier, trapping the water behind it.
- Class 2 – A wallcovering with a permeability rating between 0.1 and 1 – this indicates that water vapor will have a difficult time permeating the wallcovering. While the wallcovering allows for some breathability, it will also trap some moisture.
- Class 3 – A wallcovering with a permeability rating between 1 and 10 – this is the last classification and allows for the most breathability. However, it does still trap some vapor.
If a wallcovering or wallpaper has a permeability rating over 10, it is considered very permeable and there is low risk of vapor being trapped.
Why You Need to Know
The more water vapor your building is likely to have, the higher you want your permeability rating to be. For example, salons and hotels will have a lot of vapor in the air. To ensure that it does not get trapped, it is best to have a wallcovering with a higher permeability rating so that the walls can breathe.
It is most important for buildings and facilities where there is moisture inside the walls themselves. If the wallcovering traps the moisture, both the walls and wallcovering will have a shorter lifespan.
Some wallcoverings are perforated to increase their permeability rating. Because commercial wallcoverings are made of heavier materials, they tend to have lower permeability ratings. The perforation process can improve their rating so that rot and mold issues are less likely to occur.