Hi folks. I'm building a cordwood chicken coop, and I want it to have a dirt floor. I used a dirt floor/deep litter method with great success in Alaska, and want to do the same here in Vermont. I'm planning a 10 x 13 foot, rectangular, wood frame cordwood building like the Log End Sauna in Rob Roy's books.
Harvey Ussery suggests burying the foundation 18" deep to keep predators out. So I had a friend excavate an 18" deep rectangular trench. My plan was to build a foundation of three courses of concrete block, which would raise the foundation 6" above grade, at which point the frame and cordwood walls would begin.
Then the ADVICE started rolling in: It will frost heave. In Vermont foundations would have to be 4' deep, not 18" to avoid frost heaving.
I don't want to go deeper -- that would be a crazy big foundation. So what's the best approach? Stick with concrete blocks, which will be mostly buried to a depth of 18"? Or, my Plan B: bury hardware cloth or metal flashing to 18" around the outside to create a predator barrier, fill in the trenches, create a floating foundation on top with sand and either poured concrete or just one row of concrete block?
In Alaska I inherited a small stone building that worked just fine, so I never had to tackle the foundation/frost heaving problem. But I'm well aware of the effects of frost heaves, and I don't want to have my coop doors get stuck in the middle of winter.