Insulating the Floor

A comfortable house is a great source of happiness. It ranks immediately after health and a good conscience.

– Sydney Smith, writer and clergyman, 1771 – 1845

The same kind of foam-and-OSB panels that are ideal for insulating the top surface of the cabin roof are ideal for the top surface of the floor if you’re building in a region that gets cold weather and has some kind of heating season. But to understand the challenges behind insulating floors built over open foundations, you need some background.

Cabins typically don’t have basements, and this means floors will be unbearably cold in winter unless you do something about it. Some people insulate between floor joists with fiberglass batts, but this is a terrible choice for several reasons. Over time this kind of insulation falls out, mostly because of the vibration of foot traffic above. It always happens. Fiber-based insulation is also susceptible to moisture and mouse infestation when exposed in an open floor frame, and it’s cold on windy days. Like I said, it’s a bad idea all around.

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