I'm putting together my gameplan for building (actually rebuilding) a small shed for the yard. It's going to be a 10' x 16' saltbox. I have a couple of questions I was hoping someone could help me with. First, on of the 16' walls will be partially below grade (the shed is going to be built into a small slope) so I plan to use pressure treated sheathing on that part, as well as applying an additional wood preservative (cuprinol or other product?). Should I also apply another barrier such as plastic sheeting or typar? And would I gain anything by also using pressure treated studs to build the walls that are below grade? My initial thought was to build a 3 or 4' knee wall on the offending side and then build another wall section from regular studs to attach to the top. The question that arrises with method two, how do I frame the windows in. Assuming there would be a double sill/header where the knee wall meets the upper wall section would I need additional jack studs in the knee wall, under the window edges?
Second area of concern is the "foundation". The floor of the shed will be crushed stone. I plan to dig a trench under footprint and put in 8" to 10" of crushed stone with drain pipe just inside the walls, then lay 6x6 PT timbers surrounded by crushed stone with the tops at grade of the finished floor and then build on top of those (PT sill plates would be nailed to the 6x6 posts. Does this seem like a horrible idea? The current construction (not my project) utilized 4x4 posts installed at the corners of the shed. They were put in at least 2' into the ground (I haven't dug any further to see just how deep they were) and they continued up the the top of the wall of the shed (existing shed is gambrel style so the wall is only 4' above ground before the roof angle). Does this seem like a better idea or even an acceptable method? to be honest, despite all the problems with the current shed, It does seem that the 4 corners are still square.
Thanks in advance for any help and advice.