It is common in this context to refer to SD-values. During the course of an airtight component’s life, water migrates through the air layer layer equivalent to diffusion (Sd). When the thickness of an airtight component is 4 m, water vapour would take the same amount of time to pass through it as it would through a layer of air 4 m thick. As a rule of thumb, a vapour barrier is one that has a Sd value greater than 1,500 m. Within this range, all values are considered to…
Read MoreAluminium Foil for Vapour Barrier
