Does Insulation Cladding Prevent Building Walls from Breathing?

Doğal İnallı / Austrotherm Turkey Marketing Manager

As is known, thermal insulation cladding is an application that prevents heat loss in building walls by covering the exterior walls of buildings with various thermal insulation boards and then coating these boards with a final layer of decorative render. Over the past 10 years in our country, the importance of thermal insulation in building walls has been recognized, whereas in Europe, thermal insulation cladding began in the 1980s. Today, the level of thermal insulation cladding applications in our country reflects Europe's state in the 1980s-1990s, both in terms of insulation board thickness and application methods. So does this type of thermal insulation cladding weaken the breathability of building walls? Does it prevent the building from breathing? First, let us clarify the concept of building wall breathability. Building wall breathability means the release of water vapor from the air inside the building or home through the walls via diffusion. In other words, it is the preservation of indoor air quality as a result of removing moist air from inside to outside. As a result of thermal insulation cladding applied to building walls, the passage of water vapor from the air inside the building or home through the walls should not be prevented. For this reason, the system components used in cladding must be made of materials that do not block water vapor transmission. When selecting all materials from the thermal insulation board to the final render coat, water vapor transmission coefficients should also be taken into account, and those that are relatively low should be selected. But how? Every building material has a resistance to water vapor transmission. This resistance is denoted by the μ - mu symbol and indicates the relative magnitude of the building material's water vapor resistance in comparison to the water vapor transmission resistance of a stationary air layer of the same thickness.

This is also called the water vapor permeability resistance coefficient. Air's resistance to water vapor transmission is determined as μ = 1. Below are the μ mu values of Austrotherm EPS thermal insulation boards and some building materials;

• Walls built with bricks (vertical perforations, AB class) μ(mu) = 5–10 • Normal concrete μ(mu) = 80–130 • Wood μ(mu) = 40 • Austrotherm EPS μ(mu) = 20–40 • Air μ(mu) = 1 As can be seen, in cladding applications made with Austrotherm EPS thermal insulation boards applied to building walls, the water vapor permeability resistance coefficient is much better compared to concrete surfaces used in the building, at the same level as or below wooden window frames. In other words, it allows water vapor transmission at least as much as wooden frames do and breathes better than the concrete surfaces in the building. Brick used in building walls has a vapor transmission resistance over it. However, since it is certified to TS EN 13163, EPS products used for building thermal insulation in Europe and Turkey have vapor transmission resistance within the limits permitted by the standard, and they are produced and marketed as CE-certified with this standard certification. As is known, products bearing the CE marking on their label are products that have negligible or no harm to the environment and human health. Therefore, thermal insulation cladding made with EPS thermal insulation boards does not obstruct building breathability; in addition, while providing thermal insulation to the building, it protects the building structure and extends the building's service life. Austrotherm is an international EPS production company based in Austria and is one of the leading EPS manufacturers in Eastern Europe for thermal insulation cladding. It manufactures and sells EPS thermal insulation boards in 11 countries in Europe. In Europe, EPS thermal insulation boards used for building wall thermal insulation, i.e., cladding purposes, have been preferred for years and today are consumed in thicknesses 10–15 cm greater than the Turkish cladding market.