My biggest question right now is which foundations to go with. I've read various things. The region has 'continuous permafrost'. I don't know what depth. I know that if you build on permafrost you can upset the thermal dynamics of the ground and it may cause your foundations to sink. A building will shield the ground from sunlight in the summer and the heat from the building will create more warmth in the winter.
Some people say you have to place your foundations below the level of the permafrost and in the same sentence they say the permafrost may only be a few feet deep, but could be over 100 feet deep...!
Some people say wooden pilings, some say concrete (but that can crack with root penetration even if it's reinforced with rebar), others say hollow metal cylinders (but they can bend).
No one seems to have a definitive answer. It's all, hmm, depends on the soil and permafrost depth.
Well, the soil is sandy silt, five to six feet, covered with an organic layer. The depth of the permafrost is unknown, but definitely what they call 'continuous permafrost', as opposed to seasonal.
Here's my thinking:
1. Tapered, kiln fired reinforced and treated timber pilings driven ten feet into the ground and rising another 8 feet above the ground. If it does sink, I can jack it and reinforce it with some more pilings.
or...
2. Dig a 4 feet trench, fill with concrete reinforced with rebar. Apply mortar to the top then build a three feet high foundation wall of local stones and mortar, level it off, drill in some threaded screws to secure the flooring frame.
The benefit of the pilings though would mean the house is higher from the ground. If I insulate the floor well then the heat shouldn't get down to the permafrost to upset it too much, and also, if I keep the space beneath the house open then some sun will get in during the summer - as opposed to completely blocking it off with stone and mortar.
I'm really erring on the side of reinforced tapered and treated timber pilings.
Does anyone have any good suggestions?
I was planning on laying the foundation pilings at the end of July and getting the flooring on. Then leaving it to settle for a few months until I can get back again and start on the walls and roof.
The Outlands - Build your own log cabin
Building a log cabin in Alaska, preparing the land and peeling logs.
It's frustrating. The foundations are the most important thing. But I've yet to find anyone who agrees on the best foundations to use in sandy silt with continuous permafrost.
If I go the timber piling route and it all sinks - I'll be sure to post and let you all know...