Tub/shower Surround Repair [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-15-2007, 11:40 PM
Hello all. My name is Mike. This is my first post. My 35 year old tub/shower surround is tiled with 1 3/8" x 1 3/8" x 1/4" glazed tiles. The grout lines are a little less than 1/8" wide. There is a 16" wide "cement-type" backer board above the tub and drywall above that. The tiles were installed using some type of adhesive. Fortunately the tub is located above an unfinished area of the basement. While replacing a leaky drain trap I noticed a wet area on the backer board on the long side of the tub near the front corner. I removed the existing caulk along the tub-to-tile interface and up the side wall - front wall corner and recaulked with silicone caulk. That didn't fix the leak.

I checked the grout and found that the grout on the front 18" of the side, while still hard, had developed several cracks and pinholes. I tried to grind out the grout in the affected area using a Dremel tool, with the grout removal base and a 1/16" grout remval bit. The tool removed the grout, but was slow and I quickly learned that the bits are very fragile (and expensive). While using the Dremel, the tiles in the area I "degrouted" seemed to be well attached. I switched to a Fein Multimaster tool with a carbide grout removal blade. This tool removed the grout fairly well, but its vibratory action removed several tiles as well. I looks like my leak was in the corner where the long side wall meets the front wall about 16 inches above the cementboard/drywall seam. Neither the seam nor the corner joint were taped. I've removed all the loose tiles below the leak in three vertical rows (about 5 inches from the corner) on both the side wall and front wall. The tiles beyond the leak affected area seem the still be well attached. I removed a few tiles above the leak area by heating them with a heatgun and gently prying the off of the drywall. The drywall and the cement board both seem to be in pretty good shape. I didn't see any mold forming.

Can I tape the corner cementboard/drywall seam with a fiber re-enforced tape and use a thinset mortar to reattach the removed tiles? Or, will the thinset raise the tiles objectionably above those tiles still attached with the original mastic? If I can't use thinset, is there a preferred adhesive that I should use? Also, I plan to regrout a larger area than the area effected by the leak. Do I need to remove all the old grout prior to regrouting or is half of the tile thickness (about 1/8") sufficient?

Thanks for any advice that will increase my chances of a successful repair. (My wife is really getting tired of the plastic sheet that I have taped over the shower walls.)

You have an excellent forum that provides access to a lot of knowledge.


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02-15-2007, 11:46 PM
Hi Mike, welcome! You need to use cbu tape which you can find at most big box stores, usually called Durock tape. Use thinset to reset the tiles.