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Alert: Beware the insulation contractor who does not include air sealing

Consumers should beware of insulation contractors who offer to insulate attics without checking for and sealing attic air leaks. If the offer to insulate does not include sealing air leaks, then the contractor is in violation of the Minnesota energy code, which says “Attic insulation may not be installed unless accessible attic bypasses have been sealed.”

Before building science demonstrated the role that air leaks play in energy loss, most people assumed that insulation was enough to stop heat flow through a home or building. Although insulation slows heat transfer, it is easily compromised by air flow. The only way to stop this air movement—and associated heat loss—is by eliminating the air leaks between the inside of the house and the outside. First step to tightening one’s home: Identify air leaks and seal them.


The illustration above shows how warm air can leak around vents in the attic if not sealed.

The Minnesota Department of Commerce, Division of Energy Resources (DER) encourages consumers to conduct careful and thorough research before investing in any energy-efficiency technology or improvement for their home. The benefits associated with many such products can vary depending on a number of factors, including the unique characteristics of a consumer's home and the climate in which the consumer resides. For instance, a radiant barrier product for attics that has been pitched to Minnesota homeowners has virtually no energy-saving value in Minnesota.

Adding insulation is a great way to reduce the amount of energy that you use, but it only reduces energy costs if it is installed per the manufacturer’s instructions and in conjunction with air sealing activities.

Before signing with a contractor, get at least three bids and conduct due diligence. Utility companies and nonprofit energy groups may have contractors they recommend, and utilities may offer consumer rebates for insulation work. Get references and check sources like the Better Business Bureau of Minnesota (651-699-1111 or 1-800-646-6222) to see if there are any complaints or actions against contractors.

For more information on insulation and other energy-efficient measures to improve your home, contact your utility or DER at 800-657-3710 or 651-539-1886 or visit Division of Energy Resources provides a free home energy guide called Home Envelope that offers detailed information about insulation, saving energy, and selecting a contractor.