Air Sealing for New Construction
Minimizing air movement in and out of a house is key to building an energy-efficient home. Controlling air leakage is also critical to moisture control. Before developing an air sealing strategy, you should also consider the interactions among air sealing materials and techniques and other building components, including insulation, moisture control, and ventilation. This is called the whole-house systems approach.
It’s always best to use techniques and materials identified as best practices for your site and climate. Climate-specific construction details are available through Building America.
Here are some general air sealing techniques and materials for new homes.
Air barriers block random air movement through building cavities. As a result, they help prevent air leakage into and out of your home, which can account for 30% or more of a home’s heating and cooling costs. Although they stop most air movement, air barriers are not necessarily vapor barriers. The placement of air and vapor barriers in a structure is climate-dependent, and it’s wise to work with building professionals familiar with energy-efficient construction in your area.
Many of the materials used in a house as structural and finish components also act as air barriers. Sealing all the holes and seams between sheet goods such as drywall, sheathing, and subflooring with durable caulk, gaskets, tape, and/or foam sealants will reduce air leakage. In addition, some types of insulation, when densely packed in wall cavities and crevices, can reduce airflow as well as heat flow.
The most common air barrier material is house wrap, which is wrapped around the exterior of a house during construction. Wraps usually consist of fibrous spun polyolefin plastic, which is matted into sheets and rolled up for shipping. House wraps may also have other materials woven or bonded to them to help resist tearing. Sealing house wrap joints with tape improves the wrap’s performance by about 20%. All house wrap manufacturers have a special tape for this purpose.