Thanks all. This is more work than I thought. But its for my three boys so it's got to be worth it. I don't think foot prints would be much of a problem because the 2" foam board is going to go over it. Frost won't be much of a problem because we are just east of Dallas. Hardly ever freezes here at least enough to be much of a heave problem. I will let you know how it turns out. Seem to be so busy at work and the kids functions after work in evenings with schools ending I can't work on it as fast as I want to. Should have the perimeter poured and sand compacted this weekend. Maybe the liner up by Memorial Day. I hope.

Aranon