Typical purpose or application: Knee walls, skylights, and crawl spaces.
A knee wall is a vertical surface that separates livable conditioned space from unconditioned space. These are commonly found in homes with two floors where an upstairs wall meets the attic space above the downstairs ceiling. If any rooms have changes in ceiling height like raised or vaulted areas, you most likely have exposed knee walls that desperately need spray foam. We use a two-part expanding spray foam. This is a state-of-the-art upgrade because it serves two purposes simultaneously. It insulates with a resistive insulation value of R-6 per inch of thickness and it provides an air barrier that stops unwanted air movement. Typical knee wall insulation might be ok, but we consider it non-performing if it isn’t supplemented with spray foam. As displayed in the picture below, unconditioned air flows freely through insulation without spray foam, which is how the dark spots appear. An insulation batt that is un-faced or missing spray foam essentially just becomes a dirty air filter.
Our goal is to completely cover and air seal all exposed batts with spray foam. Pretend it is a cold and windy day. You are wearing a decent sweater, but the cold air passes right through…rendering the sweater ineffective. The insulation quality of the sweater might be sufficient, however, a windbreaker is necessary for the sweater to do its job effectively.
In both attics and crawl spaces, spray foam is the windbreaker for your home’s sweater.