The sunroom floor was interlock and I asked you the best way to fix it. (Not telling you half of it was already out on the front lawn as I expected you would side with me and not my husband). Your advice was to just spray because it was too big of a job to replace. You were right but the floor was already out on the lawn. We removed a foot of sand and replaced with 8 inches of stone dust. It has worked wonderfully with no this summer. Now we want to down ceramic tile. My husband wants to put down a 2x6 pressure treated wood flat on the gravel and on top of that a frame of 2x6 joists 16" o. c. with 2 sheets of 1/2 plywood and then tile. I wonder if any insulation should go under the floor for warmth.
Answer:
As soon as you introduce the cavity between the joists, you're creating ideal habitation for all kinds of things (mice, squirrels, raccoons, skunks, bees, etc.) so I'd far rather see a simple, poured concrete, 3" thick pad poured and then apply your electrical heating element before the ceramic tiles. One inch of wood is not enough under tiles anyway and there's just too much opportunity for all kinds of other problems with it. The concrete pad can be re-enforced to add integrity and you have a floor for the rest of your days.
