How can I tell if the walls of my house are properly insulated?

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Answered by Tim Snyder, Guest Editor

During a home energy audit, a technician can use an infrared camera to detect temperature differences that indicate air leakage and missing insulation. If you have an energy audit done during cold winter weather, the major areas of heat loss and cold air infiltration will be easier to detect. There’s also a low-tech way to see if wood-frame walls contain fiberglass insulation. First, drill a small hole through the gypsum wallboard in an exterior wall. Then insert a wire coat hanger with the tip bent into a small hook. You should be able to feel some slight resistance when the wire contacts spun fiberglass, plus the hook will pull some fiberglass back through the hole. You’ll know a hollow stud cavity by feel.

About the author: A journalist specializing in sustainability, energy efficiency and home improvement topics, Tim Snyder is a former executive editor of Fine Homebuilding and American Woodworker magazines. Tim's recent work includes a green remodeling manual for the Environmental Protection Agency, and a chapter on “Smart Shelter” for The Whole Green Catalog. Tim’s blogs and web content can be found at,,,,,, and other sites.