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Oilerfan
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# Posted: 21 May 2013 06:48pm
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Spring is finally here up in Canada after a very long winter. Let the cabin building begin! Outhouse done this weekend and piles laid out.
I was talking to a local contractor and he was questioning my decision to install sonotubes without a belled end. I have also spoke to a geotechnical engineer on the same issue and he told me that it would be good but not crucial. I plan to install the piles 1ft below the frost line with 6-12in of gravel below. I am dealing with a clay soil so frost is definitely a concern. Any comments?
I have also looked at adjustable post connector however I can't find many examples of these being used on a building structure, seems they are typically used for decks/etc.
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VTweekender
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# Posted: 21 May 2013 07:02pm - Edited by: VTweekender
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Forget the gravel, it will collect water to freeze and heave.........instead just throw a bag of kwikcrete in and poke a few holes in them so they will get moisture and harden over time, set the tubes on those bags...
and yes, those adjustable post connectors are for decks..
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bldginsp
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# Posted: 22 May 2013 08:58am
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One foot below the frost line should be more than enough. If the soil below your footings never freezes it can't heave your footings. Never heard of the need or benefit of a belled end. Stands to reason that a wider footing will support more, but with small cabins you don't need the extra support.
Adjustable post connectors are also used in log construction where shrinking of horizontally laid log walls causes the roof eave line to drop many inches.
Since your footings are well below frost you should never need to make any height adjustments.
Send pictures!
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fpw
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# Posted: 22 May 2013 11:18am - Edited by: fpw
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Screw Jacks can be used for posts. A building can sit on them if you like. Just check the building load and make sure the jack is rated for the size of the building and the number of posts.
Here is a link:
http://www.loghelp.com/p-1831-screw-jacks.aspx
Or, you could have some welded up with plate steel and all thread.
Screw Jacks
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Installed in a post
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GomerPile
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# Posted: 22 May 2013 03:25pm
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Be sure to put some 1/2" rebar in the piers to prevent shearing.
cheap insurance install 2-4 inches of rigid foam about 24 inches around each pier about 16 inches down. This will insulate the ground and hopefully keep it from freezing. It also will divert water away from your piers...soil with no water can't heave.
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ICC
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# Posted: 22 May 2013 06:20pm
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Quoting: Oilerfan belled end.
the belled end is a substitute for pouring a footing the idea of which is to increase the footprint to spread the cabin weight over a greater area. when the bottom is below frost level heaving should not be a problem.
the best belled ends are from Bigfoot.
skip the gravel. pour the footing or the belled end on bare undisturbed dirt in the hole bottom. gravel is done when we make a permanent wood (framed) foundation without using any concrete and then it has to be tamped in small layers (called lifts).
done right you do not need adjustable thingys at all.
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Oilerfan
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# Posted: 28 May 2013 01:08pm
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Spoke to a couple of local contractors and they confirmed frost is going to be an issue even if i go down 6ft. Both old boys that know the area well. The only way to battle it is belled out footings but that would be a big undertaking for my little 12x16. After many, many discussions with these guys, geotech eng, others...we finally settled on a 3ft depth for each footing and living with the frost heaving. Going to look at the adjustable posts or jacking/shimming as required to deal with frost. Neither is a perfect solution but for a weekend small cabin I can't justify $1K or $2K worth of foundation work. Has anyone used the adjustable posts for a small cabin application? Is this completely taboo? Maye only use the adjustable backet on a few of footings?? Any comments would be great!
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leonk
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# Posted: 28 May 2013 10:06pm
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What's the soil like?
I find it hard to believe the frost line would be below 6'...
Here in ON, it's 3-4, but I spoke with a guy digging holes for a living and he didn't see more than 2' of frozen ground in his 10-20 years of working...
Why don't you build w/o foundation then?  better no foundation, than foundation heaved by the frost... me thinks, but not expert...
look at what alaskaman did on permafrost.
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OwenChristensen
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# Posted: 29 May 2013 07:34am
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I have built at least one hundred cabins that float on top the ground. Frost is a big problem here in Northern MN. ( poor soil). If your cabin is less than 14' wide and 24' long approx. , it can be supported on two skids. Not three, three is a problem because one will move more than the other two. They must be large, I use laminated together 2x8's treated. By staggering joints you can make them the length you need. They should be supported directly to the ground if you can dig it flat, if it's a slope, you can support it with cement block pad six to seven feet apart. Make them double wide 16'' x 16'' with the top blocks perpendicular to the beam. If you have good gravel, you have a excellent spot to build.
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