Tuesday, June 1, 2010

INSULATION: Startling Insight

People naturally think that if you cover 98% of a surface with insulation, you'll get 98% of the performance. This thinking is horribly wrong. Gaps and missing insulation create a hugely disproportionate performance penalty. If you install R-38 batts in an attic but leave 0.5% of the surface area uncovered, you end up with R-32 (16% reduction in R-value, or insulation performance.) Leave 2% uncovered, and you drop to R-22 (42% reduction.) So, with 98% of the coverage, you only get 58% of the performance! This is why "QII" (Quality Insulation Installation) is so important. Predominantly insulation is NOT installed this way, it's almost just thrown into walls cavities and attics, and small gaps often occur which add up to a huge loss in performance. There is an additional cost for QII when you are getting insulation installed, but obviously it's very much worth it! (Derived from Fine Homebuilding, Winter 2009)

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