The leakage of air from within a dwelling through its external envelope contributes considerably to its overall heat loss and energy consumption. As building products have developed, and new air tight membranes have become more of the norm, air leakage is becoming less likely to occur. Often the majority of air leakage can be eliminated firstly with good craftsmanship without the requirement of air tightness products and this should always be the first port of call in achieving a low air permeability result. Concrete slab floors, timber frame builds and suspended floors are some of the main elements which may require barriers etc. to help with the reduction of air leakage.
As with all areas relating to building energy the earlier we are involved in a project the better as we can advise on how the desired levels of air tightness can be achieved. If we are responsible for your Design BER (DEAP Assessment) we will already know what level of air tightness is required to achieve compliance and can act accordingly.
Now in the current NZEB regulations there is tighter measures on air permeability and with any properties with a reading of 3m3/hr.m2 mechanical ventilation will be required within the dwelling.