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Thread: Perma Frost

  1. #1

    Default Perma Frost

    I would like to make a request from Doug, experienced contractors and others who have knowledge of working with permafrost to create a resource here on how to deal with it.

    I am curious as to the different ways that people deal with it. What are the requirements for insulating it. I am also curious as to what requirements there are for drainage. Foundations, poles, building above it and so on. This would make a great sticky. There is a lot that people who have never dealt with do not understand. By people I mean mostly me and am looking for a good education on the matter. Thanks.

  2. #2
    Member AKDoug's Avatar
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    This Doug lives in a part of Alaska where there really isn't any perfmafrost. I don't have much to add I love giving advice on other parts of building, though. And I love learning from others on how they handle construction problems.
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    you should familiarize yourself with the cold climate housing research center (CCHRC) based at UAF. They have produced documents and done research which will tell you most everything you want to know.

    Contact them with your specific questions.
    http://www.cchrc.org/


    Really your best bet is to avoid the permafrost. If you can't, you really should bring in a substantial layer of gravel and build on pilings or raised footers to allow air to circulate underneath and the gravel will insulate the ground from your house heat and keep the permafrost frozen.

    Where are you looking at building?

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    Member AKDoug's Avatar
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    Andy brings up a good point. THe CCHRC is a source of very valuable information on all aspects of building in Alaska, not just foundations. It has changed the way we build in our area substantially in the last 15 years.
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    The #1 best piece of advice is to avoid permafrost. The reason we keep stating over and over to people asking about buying land to go out and look at the land in the differenct seasons, look at the trees, see where the water runs during breakup (and overflow) etc, is that it's 10,000% easier to avoid building on problem land than it is to engineer solutions. IMHO difficult to build on land isn't worth building on, even if the land is free. It's kinda like cancer, you really want to avoid it, as the cures are difficult and not guranteed.

    I don't know all the ways that people have dealt with it for private residences, but I've seen the following methods used in industrial applications. The first method is to build the building on piles, so it is high enough above the ground that the heat from the building doesn't melt the permafrost. This seems to work fairly well, but the pilings are substantial, typically driven 40 feet into the ground, with a thick gravel pad laid over the permafrost, and the piles raise the building 6-10' above grade.

    The next method is to use piles that have passive refrigeration units, most typically seen on the supports for the transalaska pipieline, but I've seen those units used for buildings that are built on grade as well.

    The next method is active refrigeration, a giant pump and compressor is used to chill a refrigerent and run it under the foundation of a building built on grade.

    The last technique is to build the building on a gravel pad on grade, and at some point in the future either deal with the subsidance, or say oh crap and live with a crooked building. The oh crap method seems to be more popular than dealing with the subsidence.

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    Member big_dog60's Avatar
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    Another option I have seen in areas with shallow permafrost is actually excavate beneath the premafrost. If you then put a building on grade (assuming it is heated year round) it won't re freeze.

    I don't know where you are at, but in many areas of the state removing the vegitation off the surface will allow the heat to penetrate deeper in the summer and melt your permafrost. This might take several seasons to stabilize depending on how much permafrost you have.

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    Thank you for the link Andweav very informative
    Quote Originally Posted by andweav View Post
    you should familiarize yourself with the cold climate housing research center (CCHRC) based at UAF. They have produced documents and done research which will tell you most everything you want to know.

    Contact them with your specific questions.
    http://www.cchrc.org/


    Really your best bet is to avoid the permafrost. If you can't, you really should bring in a substantial layer of gravel and build on pilings or raised footers to allow air to circulate underneath and the gravel will insulate the ground from your house heat and keep the permafrost frozen.

    Where are you looking at building?

  8. #8

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    I am not up in Alaska yet. Some health problems and a couple of surgeries has slowed my plans down. I am basically asking, because I am a bit of an engineering nut. I love to see how people deal with problems and issues. Eventually will make it up there and set up shop. Until I do I like to learn as much as I can ahead of time and to understand as much as possible. This particular topic has always interested me.

    Do Alaskans use the permafrost for cold storage rooms? Is it feesable or does it melt too easily.

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    Very few people in Alaska live/build on permafrost, though it does happen, though mostly for industrial facilities where there is no other option, and where the builders can afford expensive engineering solutions. Most of us just avoid it by building in well-drained areas and/or in the southern half of the state.


    Most areas with permafrost are not desirable for building for many other reasons.

    Some otherwise nice for building hillsides in the interior do occasionally exhibit shallow layers of permafrost, which are generally avoided, but might be exposed, allowed to thaw, "mucked out", allowed to thaw more, mucked out again, etc. until the frost layer is removed and the foundation is placed on dry substrate.

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    Member AKDoug's Avatar
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    Lots of recreational cabins end up on shallow layers of permafrost. In that case, the recreational value of the structure will overide the difficulties of building on that type of ground. I know at least two places built on lakes north of Trapper Creek that ended up having permafrost under their structures.
    Bunny Boots and Bearcats: Utility Sled Mayhem

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    I was going to add regarding recreational cabins, that rule number 1 is still to avoid the stuff, but, barring that, a couple of jacks and a pile of 2x4s with an adjustable foundation are about as fancy as most engineering solutions get. would you agree akdoug?

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    Plunk your $17 bucks down for a copy of Eb Rice's book, Building in the North. Eb did a good job on that book. It's updated from the original. Some construction techniques have changed, but permafrost hasn't. There are no panaceas for building on permafrost. If you arre lucky enough to have ice-poor thaw stable permafrost, you're golden. If you have ice rich material at an in situ temperature of about 31.9F, almost anything you do is going to screw it up. Good luck to you.

    The CCHRC is a great resource, too.

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