Posted by Larry on September 04, 19100 at 20:19:58:
In Reply to: What to use to install Porcelin Tile posted by julie jasparro on September 04, 19100 at 17:45:17:
: My husband and father have started to install grade IV porcelin tiles to my kitchen floor, which we first put 1/4" plywood over. They used Mastic I for the adhesive. All the tiles are lifting. Should we have used thin set to install the tiles? We used the same mastic on a bathroom floor, which we used grade 2 ceramic tiles over the linoleum. These tiles are stuck solid, but did take a couple of days to dry. How could ceramic tiles over linoleum stick, but not the porcelin on the plywood? Is it the plywood we used? Is it the mastic? Help!!
: The lady at the tile store said we should use exterior grade plywood and extra strength (ie commercial grade)adhesive when putting down the porcelin. I don't think we used either.
: I am ready to rip up the linoleum that probaby has asbestos and the black stuff under it so I can refinish the hardwood floors that exist under it and be done with it.
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The tile store gave you some poor information. I wonder how their own installations turn out.
I personally would not install a single piece of tile to plywood nor would I use mastic (Type 1 or any other) as an floor adhesive. Others may have their own opinion but I've seen too many of these types of installations fail. In any case a plywood substrate should be roughed up with sandpaper before tiling directly over it.
The subfloor under your tile should be at least 1 1/4" thick. At minimum I prefer 3/4" exterior grade plywood installed over joists (yours may already be this) with a layer of 1/2" cement board installed to manufacturers instructions here:
5/8" minimum plywood subfloor recommended for DURAROCK:
http://www.usgcorp.com/diycb/diycb2.htm
1/4" HardiBacker may also be used on 3/4" plywood subfloor:
http://www.jameshardie.com/hardibackerinstallation.htm
In addition a latex modified thinset or non-modified thinset mixed with an acrylic latex admixture should be used to install porcelain tiles. I prefer the back butter method for this type of installation as it offers 100% coverage.
On the bright side because you used mastic to install the tiles you may be able to clean them up for a proper installation.
Good Luck, I hope it works out for you.