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Tile Backsplash Substrate

I'm going to be installing a tile backsplash. The issue is that before the remodel, the backsplash was Formica glued onto the drywall.  In some areas the Formica came of clean. In others it tore off the paper facing of the drywall. In others, it came off leaving the glue surface on the drywall. It is pretty flat, and I could sand it down, but will the mastic stick to the glue, or should I just rip I all out and put the backer board in?
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Posted 2019-06-10T13:53:07+0000  by Springbank Springbank

Hey Springbank,

Thanks for your question and welcome to the community.

Depending on the location of where this tile backsplash will be will determine what type of materials to use to adhere to the drywall.

Personally, tiling over direct drywall using a mastic or any vertical rated mortar is a bad idea and poor choice. The water from the mastic/mortar can seep through the drywall, allowing for failure and possible mold issues.

You can install tiles directly over drywall however IF you use SimpleMat, which is a peel and stick tile setting mat. As the image shows below, you simply place one side of it over the drywall, and the other side will easily adhere any tiles over it. 

As I said earlier, depending on where these tiles will be installed will determine what materials to use. With that said, SimpleMat does have limitations on areas where water will be constantly on it, such as a shower wall or kitchen countertop. It also will NOT work on walkable horizontal surfaces, like a floor.

In those instances, you will need to take out any and all drywall and replace it with tile backerboard. In fact, for even the smallest chance water comes in contact with the tiles (think of near a sink, but not at it), it's best to use tile backerboard.

Let us know if you have any further questions,


Posted 2019-06-10T17:21:27+0000  by Joseph_HD_ATL
Thanks for the info. I've pretty much decided to tear out the drywall and install a backer board. The drywall is not in good shape, and I can replace the electrical boxes with the new ones that are depth adjustable. I'm thinking Kerdi board, since it's light, easy to cut, and will eliminate any chance of scratching the new granite counter top.  Scratching the counter with cement board would cause way too much spousal annoyance! 
Posted 2019-06-10T22:06:21+0000  by Springbank
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