Hi there!
I'm planning to start building a smallish cabin (12x16, no second floor) on my land as a temporary dwelling, so that we have a way to spend more time up there comfortably while we work on getting the land livable full-time. (We still need to turn our trail into a drivable driveway, add a well, etc., but it might take us a few years to get all that done. In the meantime, tent camping whenever we're up there is getting a little old.)
Anyhow, I am hoping I can avoid the trouble of building a cement pier foundation. We're on the Cumberland Plateau in Tennessee, and our soil is extremely hard clay and full of sandstone rocks. Digging is a terrible chore. My hope is that I could get away with a compromise, like digging down 6in or so, putting in a couple inches of sand/gravel, and using precast concrete pavers/cinder blocks/deck blocks, sort of like what this person did:
http://cpiat.com/g/2/be/beam-and-footing-cabin-foundation-types-plastic-base-for-log-concrete-building-on-rock-architecture-cheap-options-cheapest-to-build-how-solid-low-cost-off.jpg
It's my understanding that the main dangers of this are as follows:
1. Frost heaving. I can't find the exact frost depth for our area on the Cumberland Plateau in Tennessee (the nearest towns are Monteagle and Sewanee). I've seen some maps say 6in, others 12in. Even though our land has no restrictions, I'm reluctant to contact local authorities for an answer, just to avoid the rigamarole. Does anyone have experience with frost heaving in a relatively temperate climate with a freestanding structure? My hope is that if it happens, we could use a car jack to prop up an edge of the cabin, and just slip some wood/rocks under the supports to balance things out.
2. Erosion/slippage. It seems like another danger is that the cabin might 'walk' off its foundations. Since the site is pretty darn flat, I'm not as worried about this. But should I be?
3. Soil settling under the foundation. I'm not sure how to deal with this or account for it. Since our soil is mainly hard clay, does that make this less of a risk?
I know it's a bit of a gamble, but I'd be curious to hear from others who have taken this gamble before. It would really be a beast to put in piers, so I'm willing to assume some risk, but it would be so sad if the cabin became unstable/uninhabitable after one season.
Thanks in advance for your thoughts!
Best,
Juliet
