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Thread: Remote cabin construction on permafrost

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    Default Remote cabin construction on permafrost

    I'm trying to edjamakate myself about methods of building a remote cabin in a permafrost area.

    The pictures I seen of remote cabins are often on raised posts to keep the permafrost intact under the cabin I assume. I've also seen pictures of cabins built on gravel.

    What is the simplest and or best method of dealing with the permafrost when you hand build a cabin in a remote area?

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    Don't build it on permafrost is easiest! Other than that posts. I have seen pads too, what ever you use it will move through out the year.
    Tim

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    Mit,

    About not building in a permafrost area. Is it true that most of the interior is in a mixed permafrost area, meaning some is permafrost and nearby areas may not be and some areas may thaw one year and stay frozen the next?

    Regarding movement. How bad is it? Do folks re-level their cabins with jacks or do you just ignore it?

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    Default foundation

    Headhunter,
    Interior permafrost is called discontinuous permafrost. Means that is has random occupation in the soils.

    Here is a link to another thread along the same lines.
    http://forums.outdoorsdirectory.com/...ht=foundations

    I posted a suggestion in that thread as well. You basically have 2 options when building on permafrost. Either you get below the permafrost with a piling (post) or you build on top without disturbing the permafrost. Knowing that permafrost can run DEEP, a soil test would be prudent. I've seen $200k homes in the interior built on 10" diameter steel pilings driven 40' down in order to anchor them. Lots of time and money for something that might move around on ya.
    The other option is to build a foundation on top of the soil that covers the permafrost. The photo shows what I did on my rec cabin built on a slope with permafrost underneath. The permafrost never has a chance to melt, therefore the cabin hardly moves. I sometimes see a small (1") change from summer to winter, but I am slowly mitigating this with sawdust, woodchips and foam (peanuts, scrap, etc) around the railroad ties so they stay frozen longer in the summer.
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    Default Great post Skinnyriver

    Skinnyriver summed it up. Have also used log cribs for cabins on permafrost, the four corners sit on three-foot-high log cribbing.

    Here we are on some discontinuous permafrost; there was a layer of permafrost in the two-three foot level, and just under that is gravel, so our place is on pilings three feet deep. Wish I would have used concrete though, treated the pilings but they will need to be replaced at some point.

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    Another vote for don't build on permafrost.

    But if that isn't avoidable, the engieering solution is to either sink the foundation below the permafrost, or keep the permafrost frozen.

    If you look at the variety of oil field and pipeline modules that are in permagrost zones, they have either elevated the modules above ground 6-8 feet, or they have installed refrigeration units under the ground of the buildings that were put on grade. The refrigeration units are both self contained similar to whats used on the supports of the pipeline, or they use compressors and refrigerants to run a brine in tubing under the modules or along buried sections of the pipeline.

    A long way of saying since it's tough and expensive to deal with permafrost, most cabins aren't properly built for permafrost and slump or fall down over time. My advice would be if you have to build on permafrost, elevate the cabin as much as practical, and provides means in the pilings to level the cabin as it settles over time.

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    Why I did it my way........ <besides being stupid and just plain hard headed>.

    I spoke with as many people in the area as possible. I cruised around the lake and looked at all the visible foundations. Asked more locals, spent 6 months in deep thought...... Looked at my available time at the lake. Cost of materials VS time. Modified my plans a couple hundred times..... Accessed my ability to get a heavy machine into my lot. Looked at the available resources on my lot (sand and gravel). Priced pilings.... asked about pilings.... was told that they frost jack too. Just a matter of time. Everyone kept saying... "Don't disturb the tundra!!" Note: I know its a bit of a reach, but I really dislike cribbing. It just looks wrong to me if over 2 feet.

    So I bought a cheap wheeler, hauled it and my wagon out. Made the wife, kids, friends, etc (and myself) haul sand/gravel mix to make nice pads. Tamped them with a nice heavy home made tamper (thanks Fred). Leveled them. Then I set up my homemade blocks with adjusters. I was told NOT to pour any cement. When it moves, it is very hard to correct. I was also told that the normal pier blocks did not have enough surface.



    I used 6X6 1/4 wall box metal for the pier buckets. 1" threaded rod for the adjusters. They were built at home and went in pretty quick. Hauling sand is a bit tougher and time consuming.



    Lots of 3/16 plate to hold the beams straight, 4" angle iron in the corners and 7/16 and 1/2 bolts. Simpson ties too. The corners are 6X6 box with a wing and a plate to tie the beams to.



    Needs tie downs and cross bracing. Your ideas are welcome!

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    Member mit's Avatar
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    here is how I did it.....everything was flown in.
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    Tim

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    If you are planning on building in Alaska I highly recomend buying the book that all architects, contractors, engineers, surveyors, etc. are tought out of. It is called Northern Building Design. It is $150 on amazon but the UAA book store sells it new for somewhere aroung $50. There is a class taught each semester at UAA on this subject and the book is based on the presenters lectures in the early years of the class. It covers all sorts of construction issues that you will want to know about.

    dirtofak, has a prety good method as long as you don't mind releveling your cabin yearly, but I would suggest putting insulation board underneath the gravel.
    It ain't about the # of pounds of meat we bring back, nor about how much we spent to go do it. Its about seeing what no one else sees.

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    Default ties

    HH,

    The idea behind the RR ties was to provide as much surface area as possible for weight displacement. The photo from my last post is from the repair done to the original foundation. I originally had the same idea as bushrat with the cribbing, but on a slope and with only 4 corners @ 3'x3' cribs, the foundation shifted enough to make the back of the cabin slip off (thankfully, the back was only sitting on 3'x3' concrete pads).
    Photos of that below...
    By the way, the first photo is taken at the same angle as the photo in the post above.
    Surface area is good with a 20 ton cabin on a slope. I can get into details if you would like.
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    Lots of great information and photos here. I can see this is a complex subject I'll want to research further. I'm surprised how high the floor must be built to avoid thawing the permafrost.

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    Quote Originally Posted by garnede View Post

    dirtofak, has a prety good method as long as you don't mind releveling your cabin yearly, but I would suggest putting insulation board underneath the gravel.

    There is 12-20" of tundra crushed to 10-12" and 3-5" of gravel below each pier. I was thinking about putting wood chips around also.

    Mike

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    Default high floors

    Quote Originally Posted by Headhunter View Post
    Lots of great information and photos here. I can see this is a complex subject I'll want to research further. I'm surprised how high the floor must be built to avoid thawing the permafrost.
    HeadHunter-

    Alligators can't climb very well...bears can. There are many advantages to building high. Good place for dry storage and when it really snows, you can still see out the windows.

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    There are many advantages to building high. Good place for dry storage and when it really snows, you can still see out the windows.
    Skinnyriver,

    I see, there are many reasons to build high. How much clearance would be needed just to avoid thawing the permafrost?

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    Default circulation

    As long as the floor is well insulated so the heat from the cabin doesn't heat the ground underneath it, you should be fine. That said, leave enough airspace between the ground and your floor joists to let air circulate. One other thing...a little off topic. Install gutters on your structure. Rainwater falling from the sky, hitting your roof and dripping to the ground will create enough heat to permeate tundra and start melting the permafrost underneath. Re-directing rainwater via gutters can substantially increase the chance of permafrost remaining frozen.

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    Quote Originally Posted by Headhunter View Post
    Skinnyriver,

    I see, there are many reasons to build high. How much clearance would be needed just to avoid thawing the permafrost?
    Only 18"-24" are needed to allow for ventilation. But if you are on a hill that is going to be on the high side and the low side will be whatever it takes to level your cabin. But once you are 18" high you can start to see advantages for going higher. Storage, snow, bears, etc.

    Quote Originally Posted by skinnyriver View Post
    As long as the floor is well insulated so the heat from the cabin doesn't heat the ground underneath it, you should be fine. That said, leave enough airspace between the ground and your floor joists to let air circulate. One other thing...a little off topic. Install gutters on your structure. Rainwater falling from the sky, hitting your roof and dripping to the ground will create enough heat to permeate tundra and start melting the permafrost underneath. Re-directing rainwater via gutters can substantially increase the chance of permafrost remaining frozen.
    Be careful with gutters. If you do not have enough ventilation through your attic you will build an ice dam at the eaves. When the ice/snow slides off of the roof it can rip the gutters, facia, and sometimes the roof metal off with it. Also using gutters is only good if you direct the flow away form you building, specificly the foundations.
    It ain't about the # of pounds of meat we bring back, nor about how much we spent to go do it. Its about seeing what no one else sees.

    http://wouldieatitagainfoodblog.blogspot.com/

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