I'm going to be putting up a small home in an area of Alaska that gets down to -70 or more in the winter. I'm wondering what the best way to insulate the floor area would be. I'm planning on a saltbox style of about 200 sq ft. Not much snow, a couple feet maybe. Just very, very cold. Any suggestions?
Sprayfoam would get you the best R factor per inch but may not be practical at a remote site----Your best next bet is vapor barrier across floor joists, then as much fiberglass or rigid foam insulation as your joist depth allows then skirt the perimeter to block air movement under the building. The U of Alaska at Fairbanks has a cold weather institute that can provide a lot of advice too.-----you can contact them online
You haven't mentioned what type of foundation you will be doing (that can also be fun at those temps!). At any rate you will increase the performance of this floor if you can break conduction through the wood joists. This could be done by facing the bottom of the joists with foam board insulation of perhaps 1 to 2". You may also need to protect this if critters could get in there to tear up the foam.
Even a layer of R-5 foam will help increase the overall performance of the floor (more than R-5) and reduce moisture condensation on the joists.
Also, I-joists and blown-in cellulose will likely out perform solid wood joists with fiberglass batts.
Last time I was in AK facing those temps I was in a snow cave...plenty of insulation!
Spent many good years getting into a good deal of trouble. Wherabouts are you building?
Look to the locals. When I started questioning them, they all told me WHY not to use a standard foundation, why to use smaller windows, etc..... Don't break the tundra. Don't excavate.
200 Sq Ft. I would lay a couple beans down. Find a few 16" JCIs on craigslist and space them to match my insulation. Like 8" apart. Rim joist it. Use a double 2X to ring the floor. Put down 7/16 OSB inside the ring, then 2" blue foam, then flooring. Cover the bottom with thin pressure treated ply and 1/4 wire mesh.
I heat my "shed" at -21 with a 900W electric heater. 49 Sq Ft, warm in an hour.
My friend has a 24X24 Log. At -29 it took 4.5 hours to warm it to 65 using the woodstove and a propane heater.
I have not been out there when it is below -21 but I will learn this winter. It hits -35 often.
Ok I have to ask....how do you manage the call of Nature when its that cold and with 49 sqft to live in? I'd rather ponder the answer than fall prey to my imaginings.
If you have an outhouse here in the Great White North, you cut the seat out of a sheet of 2" high density blueboard insulation---somehow it feels warm to your tush even at subzero temperatures--- :)
Oh yes, you also don't take a magazine with you.
Hmmm. And I thought I held the speed record for gettin the business done. I'm humbled. [shocked]
Will you be on permafrost?
I think the Air Force has a metal structure that supports itself with series of supports that allow the whole structure to move but stay level and square. I think it is tied down just to keep it from moving in the wind. Will try and find a link.....
Quote from: considerations on July 05, 2009, 11:41:17 PM
Hmmm. And I thought I held the speed record for gettin the business done. I'm humbled. [shocked]
The trick is to figure out how to do either 1 or 2 without leaving your sleeping bag...minimal sq ft, and thermally efficient to boot (out of necessity). Unfortunately I'm being serious.
Quote from: considerations on July 04, 2009, 11:26:07 PM
Ok I have to ask....how do you manage the call of Nature when its that cold and with 49 sqft to live in? I'd rather ponder the answer than fall prey to my imaginings.
I ride my snowmachine to the lodge of course. :)
We use a lugable lu. A 5 gallon pail with a lid. #2 is a walk kind of thing. Dress up and hurry up!