Good evening,
I am building an ICF home slab on grade with radiant heat. We are at the stage to lay the 2″ foam, tubing and pour the interior concrete floor. My layers from bottom to top are 12″ compacted sand, 4″ of 1 – 1 1/2″ gravel, 6 mil poly, 2″ foam, radiant heat tubing, 4″ concrete. It’s been brought to my attention that the size of crushed gravel may impact the ability for the 2″ foam to lay flat and/or the foam will break during the pour. Is this really the case assuming it’s a relatively flat surface? I realize I probably should have used 3/4″ crush rock, but replacing the 4″ rock base at this point is going to be a major process. Trying to determine my options at this point, and whether this is really going to be an issue.
Thanks!
Steve
Replies
I've only done it over 3/4 stone, but I really don't see an issue. The foam may crush over individual stones in a few spots, but so what?
May I ask why you’re only putting 2” of foam down with a radiant heat system?
I'd be worried that the large stone will pierce your vapour barrier. 3/4 stone is usually used and because of the size it doesnt project out. You are going to have 2-inch long stone spikes. As soon as your install crew walks across the foam the vapour barrier becomes a pin cushion