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Thread: Permafrost

  1. #1

    Default Permafrost

    Permafrost? How do you get through it and how deep do you have to go when putting in a foundation? Right now this is one of my biggest concearns when I go to build a place.

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    Member Rock_skipper's Avatar
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    Theres pretty good land in Tok, depending on where your at I dout if perafrost is going to be a problem. If you do hit it, you might want to think about building on pilings.

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    Moderator Paul H's Avatar
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    It depends on what part of the state you are in, permafrost can be hundreds or even thousands of feet deep.

    The best advice is if you are building on permafrost, keep it frozen. Either build your house on pilings so that the heated house doesn't melt the permafrost, or if you want a slab foundation you'll need to put in a refrigeration system to keep the ground frozen. Needless to say pilings are the more practical solution.

    Permafrost is essentially frozen swamp land. If it stays frozen you can build on it. If you thaw it out, youre structure will get eaten by the swamp.

  4. #4

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    If possible, don't build on permafrost.

    If you do build on permafrost use pilings and a beam system so that you can jack your house up and re-level it every year. Don't build a big house, a small cabin might be manageable that way.

    If you use refrigerated pilings, you might be able to do it for awhile. You will need to keep your pilings below freezing by pumping a refrigerant down into the hollow pilings so that you keep the permafrost frozen. If the ground thaws you are in trouble.

    If all that is too hard....don't build on permafrost.
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    Biggest thing about permafrost is not to disturb the ground cover it.
    Houses that were built where the top cover was removed are having big trouble with sinking and heaving.
    Best way to build on it is to put down a waterproof barrier and put dirt/sand over it.
    Piling or the geodesic is the way to go for permafrost.

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    Member upinak's Avatar
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    Klick, look at this publication and map.

    http://esp.cr.usgs.gov/research/tok/index.html

    The publication has 4 maps at the bottom. All will show you permafrost in your area (if you know where you land is) and you might get lucky and they have drilled in that area and know how deep the permafrost is compared to top soil etc.

    Also, the person who did the publication has a usgs email you can contact him at.

    As for building on/near permafrost. I would suggest you find the place where it doesn't have it, and build up with gravel. You still won't know, even if you do not build on it, it anything will sink. Alaska is notorious for having old peet bogs that look like decent ground and look like it is safe and then you have a problem with flooding later as well as the house sinking. Also check if there are any dry streams that have gone thru as that can cause probelms as well.

  7. #7

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    great advice and help guys.

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    Moderator Paul H's Avatar
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    Permafrost is like the IRS, it's important to know what it is and what it does, and its equally important to avoid it all costs.

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    As mentioned above, refrigerated piles are a good way to go. Other methods are a waterproof barrier, then a gravel pad (3-4 feet thick) before a post and pad foundation for the structure. Your exact location would determine which method to pursue.

    If you are interested in refrigerated piles or thermosyphons (can be used directly under slab on grade foundations); check out http://www.arcticfoundations.com Ed Yarmak is the owner & has a TON of knowledge concerning these units. There are both passively and actively refrigerated piles, the one you use depends on where you intend to build.

    I've worked with the above mentioned units on several bush projects, they are pretty slick.

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