I want to re-tile my kitchen. The sub-floor is 2 layers of 1/2″ plywood. The old 1/4″ quarry tile is stuck in the mastic only by the “buttons” on the back so it will be easy to rip up. My questions are: do I need to use backer board set in thinset on top of the plywood; if so do I need to smooth out the old ridged mastic (by sanding?); can I/should I use mastic again; can I use thinset on old mastic on plywood. Any advice would be appreciated.
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Replies
I only use thinset for floors ...
and thinset on old mastic doesn't work.
You have to get rid of all that old mastic ... and provide a nice clean sunstrate for the new thinset.
Jeff
Buck Construction Pittsburgh,PA
Artistry in Carpentry
Thanks for your comment. Once I scrape/sand the old mastic off, do I need any backer board or can I thinset the new tiles on the subfloor which is two 1/2" plywood layers?
not trying to answer for Jeff, and others will argue, but Yes, you need something other than the plywood to set the tiles in.
are you looking to avoid the additional height of the backer board? if that's the case there are thinner pruducts such as ditra and densheild which I believe are thinner than 1/4 CBU's but I've never used either.