Air sealing a home is generally considered the most cost-effective way to reduce space heating and cooling energy use. It also improves comfort, and indoor air quality. Achieving a high level of air tightness requires more than just filling visible holes, it requires several well thought out steps. First, identify the thermal boundary.  Next, ensure that there is a continuous air barrier along the entire boundary. The key word here is continuous. The secret to continuity is to identify the large sheets of existing material, such as the exterior structural sheathing or the interior drywall, and then to bridge the gaps – or joints – between them in order to completely seal the boundary. Next, select the best air-sealing method for your project. Several good solutions exist for creating a continuous air barrier. Some are based on skilled use of materials, such as air-tight drywall (ADA) and adhesive attachment (gluing) of the structural framing to the sheathing. Others, like SIGA membranes and ZIP System, are proprietary and therefore slightly more expensive. And a newer process, called Aerobarrier, has achieved very high levels of air sealing.

Of course, there is a cost to any advanced air sealing method. Some approaches use less expensive materials, but require more labor and greater skill. Proprietary systems reduce labor, but have a higher purchase price. Every building professional must balance these tradeoffs to arrive at the desired air sealing goal with an acceptable cost. One point to keep in mind is that air sealing approaches generally cost less for a given amount of energy reduction than do other building systems, such as heating and cooling equipment or solar panels. Your energy model will be a useful tool to find the right balance for your situation.