Laying 12"x12" granite tile on plywood subfloor with or without vapor barrier?

[Jack]

I have plywood subfloor, do I need to put down a vapor barrier first?

That is in this sequence:

1 subfloor 2 vapor barrier on top of subfloor 3 thinset on top of vapor barrier (or on top of plywood if vapor barrio is not required) 4 backer board 5 thinset on top of backer board 6 granite tile

Do I do #2 for the vapor barrier above or not?

Thanks

[Joe]

Why don't you just slop on a coat (maybe 2) of the cheapest polyurethane varnish you can find on the plywood? Once cured hard, go over the high spots with an orbital sander, fill in with Bondo where needed, recoat where necessary, and you will have the perfect substrate for your tile. The thinset will have something to better than wood fibers grab on to. you'll have your vapor barrier for control and save hours and hours and $$ too. HTH

Joe

[3G]

NO

SEQUENCE REVISED | | That is in this sequence: | | 1 subfloor 2 1/2 in. backer board | 3 thinset on backer board | 4 granite tile | | | | Thanks | |