Is air sealing known to significantly reduce the number of pests (mice, spiders, ants, etc.) that come into houses?

Asked by Barb
Fort Collins, CO

It makes sense that it would, and yet I never see this advantage of air sealing touted. Even my "green" friends don't seem even slightly interested in this unsexy aspect of green, despite the potential to save $$ and have a more comfortable home. They do occasionally have bad mice, spider, etc invasions, so I'm wondering if I can validly make this case.


Lucas Johnson

Answered by Lucas Johnson

Seattle, WA

Cascadia Consulting Group

January 11, 2013

That is a great question, and I'm sure you'll be happy to know that I used to sell insect-proofing as a benefit of air sealing.

Many insects and rodents like to live in attics, walls, crawlspaces, and basements. Air leakage pathways in these areas are usually more than sufficient in size to allow insects and rodents to enter the home.

  • The most common pathways tend to be can lights, electrical penetrations, and plumbing penetrations.
  • However, I've also seen insects enter homes through bath fans, kitchen hoods, registers, and other common penetrations.

The best solution would be to hire a professional energy upgrade contractor to perform a blower door test (measures house air leakage) along with an IR camera inspection as well as smoke test. The contractor would then most likely use one-part spray foam, rigid foam board, mastic, foam covers, and other tools to seal up the leaks in your house.

One thing to watch carefully when air sealing your home is allowing for proper ventilation.

  • ASHRAE 62.2 is considered a best practice for ventilation requirements.
  • Air sealing your home has many other benefits (indoor air quality, lower energy bills, better comfort, etc.), so I always suggest to air seal as much as possible first and then ventilate as required second.

Tagged In: air sealing

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