It is difficult to construct a perfectly tight home, and we do need air exchanges to provide quality indoor air. In all climates, sealants that join building materials will develop some air leaks due to expansion and contraction; however, leaks should not be excessive.
Air barriers may be damaged during construction as the various workers install wiring, equipment, and materials. Air leaks may occur where materials meet and any place that the structure is penetrated with plumbing, wiring, and planned ventilation. If caulking, weatherstripping and other air sealing measures were not completed, leaks can occur.
Homes that have many corners, rooflines, and openings have more opportunities for air leaks. If you have excessive air leaks, communicate with your contractor about problem areas.
Air leakage in new home construction can be detected and measured by an experienced contractor or energy auditor by using blower door equipment.