Granite Tile Over MDF

Jul 21, 2003 4 Replies

I plan to use 12X12 granite tile for our kitchen countertops. We have installed a 3/4 MDF top over the counters. I have since heard that Type I mastic is not recommended over masonite, etc. Others have told me that Kilz as a primer or scarifying the MDF will allow the mastic to "hold" the tiles. Also, can the tiles be butted and grouted only in the chamfered edges or should there be a tiny gap?



Thanks for and help.



Tom


you shouldn't use mdf. if you aren't making a mortar bed, you need a thicker base.

you can use exterior plywood or chipboard. you then need to use 1/2" cement board. you then tile to the cement board.

no. use the thinest spacers for granite. 1/32" i believe. use unsanded grout.

regards, charlie cave creek, az

Having just did this, I agree with Charlie 100%...

You do not want to use MDF for a counter top...

I used 3/4 exterior grade plywood, a layer of thinset, 1/2 wonderboard, a layer of thinset, and then my granite tiles... Install came out awesome... Even built in my own customer undermount sink... Did a nice wood strip on the front of the granite to match the cabinets...

Good luck, Mark

How did you finish the inside of the hole where the "undermount" sink is?

M.C. somewhere in Ca.

cut to fit and bullnose the edges. you should consider solid surface granite. allthough i've set plenty on tops, imho granite tiles should be reserved for floors and walls..

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