Quote:
Originally Posted by Woody38
I have always been told in the past to use closed cell foam for these insulation projects. .
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This is why I posted the specifics, to discuss. Here is my reasoning: I understand that open cell will allow moisture to penetrate. This is not good for a ceiling as moisture from showers, etc will travel through the open cells to the cold roof deck unless a vapor barrier is created between the living space and the foam. Closed foam provides its own vapor barrier if applied @ 1.5" or more. Conversely, moisture from the house traveling "downwards" towards the crawl space, should, in theory, hit the "warmed floor" vapor barrier and not condense as the insulation is on the other side, allowing the floor (and vapor barrier) to stay above the dew point.In the summer, moisture should travel towards the cooler (air conditioned?) interior. However, this doesn't seem to be an issue presently - the currently visible parts of the fibre(?) sheathing below the joists aren't falling down, so I don't yet see how insulation might change that. Air can "blow" under the cottage, lowering odds of condensation on anything unless it is really colder than the ambient temp.
I have two reasons to 'buck' the conventional approach. One - it could be VERY difficult to get under the narrow crawl space, remove the ?fibre board?which closes in the bottom of the floor joists, spray LOTS of closed cell foam upwards. Clearances look to be about 16" at some parts of the crawl space from the photos I've seen. If I tried to cut holes and spray the foam downwards, as is my thought for open cell foam, and not completely fill the space with closed (or open) cell foam, it would be ideal critter country for mice to establish their own home owners association.. My hope is that the more expanding open cell foam might completely fill the void.
The other thing - open cell foam is cheaper per cubic foot I believe. If I'm going to fill hundreds of cubic feet (ouch), it is a little less ouchy with cheaper foam.
However - this is all theory on my part, save for some reports from Louisianna where some LSU folk chose open cell for the floor joists of homes built up on pilings.
Would love to hear how others are dealing w/ winterizing a camp/cottage!!!