Is Foam Board Insulation Strong Enough To Be Placed Over Floor Joists And Then Install A Floor Over It?

Monday, February 22nd, 2010 at 2:01 am

I am going to be building a 10x14 shed when it warms up a bit. I plan to use it as a shed to store my lawn tractor and garden tools but i can see a time in the future where i may want to use it as an escape (i am going to run power, tv and internet to it). I can insulate walls and ceiling later but the floor is something i think is a lot easier when you are building the shed. My first thought was to use fiberglass but i then thought about mice and potential for getting wet being so close to the ground. So i am now thinking about something waterproof which would be 4x8 sheets of foam board.
My current plan is to build the floor out of 2x6's 16inches on center. I would then build the walls and put them up. Next comes the floor made from a 1inch foam board (laid directly on the floor joists) and then 1/2 inch plywood. This would bring the floor up to the same level as the 2x4 plate at the bottom of the wall so the floor would be level. The 2x4 would take the brunt of traffic thru the door and the floor would take load from the top.
Other option would be to first put down a sheet of plywood, then foam board, then another piece of plywood on top and then build up the door ways with 1x so the floor level matches.