Wood foundation for workshop

[Steven Marshall]

I would like to build a 14’X 20′ single story workshop at the rear of my home in Indiana. It would be very difficult to pour a traditional concrete foundation due to site access, tree roots, and wooden privacy fence.

Option 1:

Sink several 6×6 treated posts in holes filled with quick set concrete around the perimeter of the struture. Build a platform supported from these posts with conventional constructions from that point up.

Option 2:

Lay 20′ long 6×6 treated posts on the ground evenly spaced on concrete pavers. Build a floor structure on top of the beams, then conventional construction from that point up. (possibly lay a thick piece of plastic sheeting on the ground between the wood and ground?)

The approx. distance from the top of the floor to the ground would be around 12-15″

Any advise or suggestions would be greatly appricated.

Thanks

Steve M.