When it comes to total home heat loss or heat gain and contributing to home energy costs, air leakage is often the greatest contributor. It is important to seal large air leaks that result in energy loss - especially those that are at ceiling and upper floor levels (since warm air rises and pulls in unwanted outdoor air from lower house levels).
It is difficult to construct a perfectly tight home and we do need air exchanges to provide fresh indoor air for human health and for combustion equipment. Air leaks may occur where materials and building components meet and at any place that the structure is penetrated with plumbing, wiring (electrical outlets and switches), and planned ventilation. That said, leaks should not be excessive. Homes that have many corners, rooflines, windows, and doors have more opportunities for air leaks.
Sealants, caulks, mastics, and weatherstripping products are commonly used by do-it-yourselfers and contractors to seal cracks and openings. Do not seal planned ventilation openings such as dryer vents.
If you are unsure about sources of air leaks, specialized contractors or energy auditors can be hired to use a "blower door" and infrared thermal imaging to pinpoint leaks.
For more information on air sealing, follow this web link: Air Sealing
