Hi Tom and Randy,Thanks for your suggestions. Both good ideas .My initial thoughts were also that a vapour barrier underneath the concrete floor would a good idea.With this building ,I'm not sure and I'm leaning against it.The lot is level,although in the final landscaping the drainage will be away from the perimeter of the building..A vapour barrier while preventing moisture from coming up through the concrete,may also trap moisture and cause heaving of the concrete during freeze/thaw cycles - as the building will not be fully heated in the winter, (my thoughts)..We are in a semi-arid climate here as well.Anyhow, that was my reasoning for deciding against using a vapour barrier in this case..My plan is to have 5 to 6 inches of gravel, rebar (10 inch grid) and 5 inches of concrete on top...However,this plan is not in stone and may change. Roof is on, door should be installed this week.This building is not deluxe.Some may ask why the height?The answer is twofold.If in the future I decide to further develop the building - mezzanine,storage,or whatever,I'll have the height.Heck, I may have to take up residence there some day.