... I'd recommend you do a couple of things:
1) Spike or cabin screw every 16 to 24 inches.
Thanks, Joe. I cut lap joints so that the timbers can't slide together. I.e., the weight of the dirt outside pushes the timbers tight together, but they can't go any further.
2) On the "dirt side" of your structure use a vapor barrier of some kind- it'll keep ground moisture from wicking in & seal any gaps that would allow dirt to seep thru the cracks.
I'm planning on mounding dirt over the whole thing, then covering it with a layer or two of heavy-duty black poly, then covering with more dirt and planting with a ground cover. We have good drainage, water doesn't stay in the hole even after a downpour. I may use spray urethane foam between the timbers. I still have the gun and a couple cans left over from building my house.
My quandary at the moment is how to incorporate a door that's tall enough to be comfortable yet doesn't look awkward.
I'm toying with the idea of building a small conventional-looking shed on top. From the outside, no one would realize that there's a large "basement" underneath it. (Watch that first step...)
I still have a couple months to mull it over. Thoughts?
i did have a project going for a new coop but i think that one will be going to the dumps and taking a little of your idea if thats alright? i dont want to seem like a copy chicken (cat)
I'm the founder of a movement! Watch out for C.H.U.D.