I understand airtightness does a lot of the heavy lifting in terms of insulating the house and keeping it warm. But I’m worried about moisture management. If the house is really well sealed up and fully airtight, will the airtightness membrane allow the building fabric to breathe, and control moisture?
A little bit of moisture ingress is alright, if it is regulated and if it can dry out in a timely manner. And that is the purpose of putting in place an airtightness strategy, to manage not only air but also vapour within the structure (walls, roof, around windows
and all other junctions) eliminating potential problems caused by moisture build up while at the same time keeping heat in and draughts out.
Different building methods/makeups may require products with specific attributes to help manage moisture. You may require technically different airtight products for
different build ups.