the air changes you are refering to are in the cavity, i had thought that earlier comments on this thread that the air changes were through out the house?
even including weep holes from cavity to the external does no explain how htere is air changes in an internal room, if blocks are properly buttered, and then plastered on the internal face and all window doors & builders opes are sealed!
the air changes you are refering to are in the cavity, i had thought that earlier comments on this thread that the air changes were through out the house?
even including weep holes from cavity to the external does no explain how htere is air changes in an internal room, if blocks are properly buttered, and then plastered on the internal face and all window doors & builders opes are sealed!
Thats a basic accepted premise in building physics. This movement can be caused by shrinking due to drying out, expansion / shrinking due to heating, movement due to differential settlement of foundations, movemnet due to increased spot loadings on building elements etc.
All builders can do is minimise the risks. Sealing around openings with membranes and tapes will significantly reduce risk of sir infiltration. You will also have issues at junctions of floors and walls, and at ceilings and walls. If plasterwork is not properly carried to screed level, and the skirting board is not properly fixed and sealed, the air infiltration will occur. Remember, concrete blocks and concrete mortar are not airtight. Also, at the ceiling, timber joists will move independent of the plastered wall so gaps may occur. this introduces a gap at the wall plate level, which is never completely air tightly fixed to the block wall... air infiltration will occur here.
refer to the UKs planning portal web site accredited details to reduce risk of air infiltration.