Question
I need to add insulation beneath my wooden floor. What materials or systems do you recommend?
I own a single-story ranch house in the San Francisco Bay Area. I would like to add insulation under the floor from the crawl space underneath the house, essentially adding it to the underside of my wood flooring. What insulation materials or systems do you recommend for minimum impact on air quality? I would prefer to use environmentally friendly materials but am budget conscious.
Answer
Cotton batts or formaldehyde-free fiberglass batts work well in crawl spaces. Emissions from insulation in ventilated crawl spaces are not likely to get into your house, but formaldehyde-free products are preferable.
Fiberglass batts are the standard, and encapsulated fiberglass batts would reduce your exposure to itchy fibers. Working your way around plumbing or blocking would be tricky, however.
Cotton batts cost a bit more than fiberglass, but cotton batts are more user friendly during installation and whenever you need to access your crawl space. The borate treatment in cotton has virtually no impact on air quality, and no protective gear is needed for installation.
Another option is cellulose insulation, which typically requires professional installation in overhead applications, and would make access to plumbing more bothersome.
For more information:
GreenHomeGuide's "Choosing the Right Insulation Delivers Energy Savings" gives an overview of insulation materials.
