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Air Sealing for New Home Construction

May 2, 2012 - 6:09pm

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Air Sealing for New Home 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.

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

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.

House Wrap

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.

Airtight Drywall Approach and Simple Caulk and Seal

Two wall-construction techniques—the airtight drywall approach (ADA) and simple caulk and seal (SCS)-- can be used to create a continuous air barrier within a house. Using one of these techniques can significantly reduce air leakage to help improve a home's energy efficiency.

The typical procedure for ADA is to seal seams, joints, and openings in the building envelope during construction. SCS is less disruptive to the construction process because seams and gaps are sealed after the exterior sheathing and drywall have been installed and finished. However, SCS is less comprehensive than ADA, and may miss some critical points inside building cavities that become inaccessible after the drywall is installed. Tests on ADA- and SCS-detailed homes indicate similar energy savings. For health and safety, a heat or energy recovery ventilator should be installed in an airtight home for proper ventilation.

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.

References 

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