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– I am laying a natural slate floor in a new house and am curious what anyone recommends. The sub floor is plywood over I joists.
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Slate, and other stone, is very intolerant of sub-floor deflection. What size joists, how far apart, and what span? Is it one layer of 3/4 ply?
I'm sorry, I thought you wanted it done the right way.
16" OC
just the 3/4 now but looking for the right combo over that - should I put an extra layer of ply and then the backer board? Basically how much should I end up with and what type of backer is best?
Thanks
16" oc, but how far do they span, and what size are they?
Many people say that a total of 1-1/4" subfloor is required.
The backer board provides a good bonding surface for nthe tile. If you have the height available, 1/2" is fine. If you're tight for space, a membrane works well. Noble CS is one, and DalTile sells it under their own brand name.
I'm sorry, I thought you wanted it done the right way.
yeah realized what you were asking after I sent the mail - 34' span with 11 3/4" size. I am looking at 1/2 the span with a beam in the basement which would reduce the deflection significantly. That said I have no problem going to 1 1/4. I would use the membrane instead to keep it closer to the surrounding floor.
Thanks for the advice!
I'm not ignoring you ... but I am out of town and don't have my span tables so I can't say what ytour situation is. But I strongly suspect that 34 ft with a 2x12 is too far for a stone floor.
I'm sorry, I thought you wanted it done the right way.
Unfortunately it's not going to make it with slate at a 17 foot span, and it's barely good enough for ceramic tile.
See:http://www.johnbridge.com/vbulletin/deflecto.pl
Billy
Thanks for the info everyone - I guess it is back to wood floors in this area (no big deal!). Glad to find out now instead of later with cracked and popped tiles!