Expert: Dan Griffin - 2/10/2008

Question
I have a closed in back porch,it sets approximately 4 ft off the ground and is closed in by vinyl siding. I would like to make it a extra bedroom. How can I insulate the floor to accommodate electric baseboard heating and what do I use to ward off critters from making a home out of my floor insulation? thank you JER

Answer
This is sounding a bit like a cart before the horse type project.  The best answer would be to create a footing and foundation around the perimeter of the habitable structure.  It sounds like you have a patio/porch type situation on piers or wood stilts.  YOu've not indicated what the existing floor structure is, or the structure of the rest of the house.  I assume the patio is joists of some size on some centers.  YOu have also not indicated whether this will be subject to inspection or code compliance, I think you would be hard pressed to get inspector approval.  If it were a typical crawl space, the critter issue would not be coming up.

Possible solutions:
Rigid foam or batt type insulation protected by a sheet goods cap on the bottom of the joists.

Rigid foam on top of the existing flooring with new subfloor and finish.

Perimeter foundation walls, removal of existing flooring, sand fill and concrete floor.