Air leakage, or infiltration, occurs when outside air enters a house uncontrollably through cracks and openings. Properly air sealing such cracks and openings in your home can significantly reduce heating and cooling costs, improve building durability, and create a healthier indoor environment.

 

It is unwise to rely on air leakage for ventilation because it can't be controlled. During cold or windy weather, too much air may enter the house. When it's warmer and less windy, not enough air may enter. Air infiltration also can contribute to problems with moisture control. Moldy and dusty air can enter a leaky house through such areas as attics or foundations. This air in the house could cause health problems.

 

The recommended strategy in both new and old homes is to reduce air leakage as much as possible and to provide controlled ventilation as needed. Note that air sealing alone can't replace the need for proper insulation throughout your home, which is needed to reduce heat flow. Before air sealing, you should first do the following:

 

Detect air leaks

Assess your ventilation needs for indoor air quality

 

You can then apply air sealing techniques and materials as needed, including caulking and weatherstripping. Air sealing is an important factor when constructing an energy-efficient home from scratch. In addition to caulking and weatherstripping, air barriers and airtight drywalls. Before developing an air sealing strategy, you should also consider the interaction between any air sealing materials and techniques with other building components, including insulation, moisture control, and ventilation. This is called a whole-house systems approach.