Ilmansulku

Ilmansulku, a Finnish term, translates to "air barrier" in English and refers to a continuous layer within a building's construction that is intended to control air leakage. Its primary purpose is to prevent uncontrolled movement of air into or out of the building envelope. This air movement can carry with it moisture, heat, and pollutants, leading to various building performance issues.

An effective ilmansulku is crucial for several reasons. Firstly, it significantly improves energy efficiency by reducing heat loss in winter and heat gain in summer. By minimizing air infiltration and exfiltration, it lessens the workload on heating and cooling systems. Secondly, it plays a vital role in moisture management. When warm, moist indoor air escapes through leaks in the building envelope and encounters cold surfaces, condensation can occur within wall or roof assemblies. This moisture can lead to mold growth, rot, and degradation of building materials. The ilmansulku acts as a barrier to prevent this moisture transport.

Furthermore, an ilmansulku contributes to indoor air quality by preventing the ingress of outdoor pollutants such as dust, pollen, and exhaust fumes. It also helps maintain comfortable indoor temperatures and reduces drafts. The implementation of an ilmansulku typically involves carefully sealing all joints, penetrations, and openings in the building envelope, including around windows, doors, pipes, and electrical outlets. Materials used for ilmansulkus can vary and may include specialized membranes, rigid insulation boards with sealed joints, or even carefully constructed layers of sheathing and house wrap. The effectiveness of an ilmansulku is often assessed through air leakage testing.