Airtightness

The passive-house standard for buildings requires an ACH₅₀ value of at most 0.6 1/h, to be demonstrated in a blower-door test.

The airtight layer must be taken into account right from the start of planning, and must be implemented with precision in detailed planning.

In timber stud and timber frame structures the airtight layer is generally located at the cladding or the vapour barrier on the inside of the load-bearing system.

In non-frame timber structures it is on the inside of the non-frame timber layer.

In non-frame external walls the airtight layer is formed by the interior plaster in all the configurations described. In non-frame construction an air seal is usually achieved by means of the interior plaster or by levelling on the inside of the external masonry.

Measuring for leaks where a beam penetrates the roof (source: Schulze Darup)

A video on airtight building:

https://www.youtube.com/watch?v=S9-lsaMmqDQ