Run-In Shed Foundation and Flooring
I am going to start building a run-in shed for my horse. I have a couple of questions that I just can't seem to find answers to online anywhere. I am going to sink the corner posts of the shed (12X12 closed on three sides) in cement and I'm going to put in a cement foundation for the shed to sit on. I'm going to dig out the inside and fill it with gravel first, decomposed granite or gravel dust on top and then stall mats on top of that. This shed will have an attached 6X12 room, split in half for hay storage and tack. Coming of the side from the hay storage/tack room will be a 12X12 covered area, with no walls, just a roof, for grooming or if my horse wants to get out of the sun without going into the stall. We may eventually put gravel/granite flooring in there also if we need to.
Here are my questions:
How deep should the corner post be sunk in cement?
How wide, how deep in the ground and how high above ground should my foundation wall be?
How deep should the inside be dug down - meaning how deep for the gravel topped with granite topped with mats? How deep a layer of gravel and decomposed granite should I have?
We intend for this structure to last a long time, so we're putting a lot into it. Thanks for any advice you can provide.