Air permeability classes

1 class (blown) — 50 m³/(m²*h) (100Pa)
2 class (not sealed) — 27 m³/(m²*h) (100Pa)
3 class (slightly sealed) — 9 m³/(m²*h) (100Pa)
4 class (sealed) — 3 m³/(m²*h) (100Pa)