Water damage happens quite often on tiled shower and bath walls, especially in older homes. In older homes, ceramic shower tile was often installed directly over drywall. These walls are susceptible to water damage if the tile's grout joints develop gaps. In modern construction, shower tile is generally installed with a moisture barrier under a base of waterproof cement board, so water damage is somewhat less likely. Even here, though, failure to maintain grout joints can cause moisture to seep beneath the tile, causing tiles to loosen. Poor grout and bad caulking can lead to moisture build-up, causing mold, wood rot, and even leaks through to living areas below the shower.
When problems occur, it is most often near the bottom of the shower stall, where the tile meets the shower base. Catching this issue early will save you a lot of money, time, and frustration. The repair work is fairly easy for a DIYer with moderate home improvement experience.
Equipment / Tools
- Putty knife
- Flat pry bar
- Utility knife
- Drywall saw
- Circular saw
- Razor scraper
- Work gloves
- 6-inch drywall knife
- Notched trowel
- Grout float
- Grout sponge
- Foam paint brush
- Cement board
- Cement board screws
- Cement board joint tape
- Thin-set tile adhesive
- Household cleaner
- Bleach (if needed)
- Tile grout
- Tile sealer
- 100 percent silicone caulk
There's no point in fixing damage that will only recur, so the first step is to determine the cause of the wall damage. In most instances, this can be traced to loose, missing grout between tiles, or caulk that is missing. These problems allow shower water to penetrate the wall and cause damage, and they are generally found low on the shower wall, down where the tile meets the shower base.
Signs of moisture include: mold, discolored grout, loose tile, and peeling caulk. If you spot these symptoms, you have found the water damage. Fortunately, water damage caused by missing grout or bad caulking is usually fairly easy to fix.
Rarely, water damage to a tile wall can be caused by leaking pipes within the wall. In this instance, the damage is usually confined to the wall where the showerhead and faucet is located, and it may be found anywhere on the wall, not just down near the base. This indicates a more serious plumbing problem that must be fixed before you repair the damaged wall—or at the same time that you open the wall to repair it.
Once you have found the damage, begin to remove the affected tiles. Depending on the severity of the damage, you may be able to carefully remove these tiles by hand. If not, use your putty knife or a small flat pry bar to slowly pull off the tiles. It’s best to carefully insert the instrument under one corner, then gently wiggle it to the other corners. Ideally, you want to remove tiles to completely expose the damaged drywall below, as well as some of the solid, intact drywall around the damaged area. Tiles may be harder to remove at the edges of the damaged area, where they are still fairly well bonded to solid drywall.
Take your time when removing the tiles, to avoid cracking them. Once removed, place the tiles into a bucket containing warm water mixed with household cleaner. These tiles will need to be cleaned since they will be reused.
Cut Out the Drywall
With tiles removed, you should see exposed drywall. Soft, damaged drywall can usually be simply broken off by hand. Once this damaged drywall is removed, mark straight cutting lines on the remaining intact drywall. Cut along this marked line with a utility knife or wallboard saw and remove the drywall.
Remove all screws or nails in the removed area. If any of the wood studs appear wet and moldy, you can clean them with a water-bleach solution. Allow the wood and wall cavity to completely dry. If you find that the wood is rotted, you will need to replace it. Any insulation that is wet or moldy will also need to be replaced.
Lastly, using a razor scraper to scrape off old caulk from the shower pan or floor.
Clean the Tiles
The tiles need to be free of any drywall residue or old adhesive before using them again. You can clean them by soaking them in warm water mixed with a household cleaner, and then using a putty knife to scrape off any old adhesive. If the adhesive is mastic (non-cement-based), try boiling the tiles in water for a few minutes before using your putty knife or razor scraper. Tiles will get very hot, so be sure to wear gloves when removing them from the boiling water.
Cut and Install a Cement Board Patch
Next, you will cut and install a cement board patch to fit the area where the drywall is removed. The cement board should be the same thickness as the drywall—for example, 1/2 inch thick cement board if the drywall is the standard 1/2-inch thickness.
Cut a piece of cement board to fit the wall cutout, allowing for a 1/4-inch gap between the cement board and surrounding drywall. Cement board can be easily cut with a circular saw.
Fasten the cement board to the studs with cement board screws.
Tape and Mud the Joint
Apply self-adhesive mesh cement board joint tape to the drywall-cement board joint. (Don't use standard drywall mesh tape.)
Following the manufacturer's directions, mix thin-set adhesive, then fill the seams around the patch with adhesive, using a 6-inch drywall knife. Make sure the seam is flat and smooth so the tile will lie flat. Let the thin-set adhesive dry completely.
For small jobs such as this, consider using premixed thin-set adhesive and premixed grout, which come in convenient 1-quart tubs.
Reinstall the Tile
Mix more thin-set adhesive and apply it evenly to the wall with a notched trowel. Set the cleaned tiles into the adhesive bed, aligning the grout joints with the existing tile. Use plastic spacers between tiles to maintain uniform grout lines.
Let the adhesive dry, then grout the tile with a grout that matches the original tile. Do not grout between the bottom row of tiles and the shower pan or floor. Let the grout set as directed by the manufacturer.
Conclude the installation by sealing the grout lines with a recommended sealer. You may want to take this opportunity to clean and seal the grout throughout the shower, as this will help the new grout blend in with the old.
Caulk the Joints
Once the sealer is dry, seal the gap between the tile and the shower pan or floor with a continuous bead of 100-percent silicone caulk. Caulking this joint is critical to keeping water out of the shower wall and preventing future water damage. So it is important to use high-quality silicone caulk and to ensure a complete seal. Avoid using a standard latex/acrylic caulk, even if it is labeled "tub and tile."
Peters, Rick. Home How-to Handbook: Tile. Sterling Pub. Co., 2007