How to Repair Water-Damaged Shower Walls

Shower head with wet tiles

Maciej Toporowicz / Getty Images

Water damage happens quite often on shower and bath walls, especially in older homes. Older homes used materials like grout and drywall versus waterproof materials to support the surrounding shower tile. However, on the occasion, old tile and bad caulking can lead to moisture build up causing mold, rot and even subfloor and ceiling leaks. Thankfully, only part of a shower wall is affected and that happens near the shower base, more times than not. Catching this issue early will save you a lot of money, time, and frustration! The repair work is minimal and can be done by following the easy steps below. 

What you need for this project

  • Putty knife
  • Flat pry bar
  • Utility knife
  • Bucket
  • Drywall saw
  • Razor scraper
  • Cement board
  • Cement board screws
  • Cement board joint tape
  • Thinset tile adhesive
  • 6-inch drywall knife
  • Household cleaner
  • Notched trowel
  • Grout and grouting tools
  • 100 percent silicone caulk

Evaluate Damage

First things first, find the source of the water leak. Most of these shower wall leaks start at the bottom of the shower wall, where the tile meets the top of the shower floor. Signs of moisture include: mold, discolored grout, loose tile, and peeling caulk. If you have spotted these things you have found the water damage!

Remove Tiles 

Once you have found your damage, begin to remove the affected tiles. Depending on the severity of the damage, you may be able to remove these tiles, carefully, with your hands. If not, use your putty knife or a small flat pry bar to slowly pull up the tiles. It’s best to wiggle the instrument under one corner and gently wiggle your way to another. Avoid rushing and cracking the tile because you will want to replace this tile. Once removed, place any tiles that have drywall or grout residue in a bucket of warm water and household cleaner for easy cleaning. 

Cut Out the Drywall

You should see exposed drywall and now you can break off any water-damaged drywall by hand. Once removed, using your utility knife, cut a line across the intact drywall,half of a tile height below the remaining tile. Remove the drywall and all fasteners in the damaged area. If any of the wood studs appear wet and moldy, you can clean them by scrubbing a water and bleach solution on them. Allow them 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 your razor scraper, 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 build up before using them again. You can clean them by soaking them in warm water, a household cleaner, and then using a putty knife to peel 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 Cement Board

The cement board should be the same thickness as the drywall to ensure that the tile will lie flat across the joint. Cut cement board to fit the wall cutout, allowing for a 1/8-inch gap below the drywall. Fasten the cement board to the studs with cement board screws, leaving a 1/8-inch gap between the cement board and the drywall. 

Tape and Mud the Joint

Apply self-adhesive mesh cement board joint tape to the drywall-cement board joint. Be sure not to use standard drywall mesh tape. Following the manufacturer's directions, mix thinset adhesive. Then fill the gap and cover the tape with thinset, using a 6-inch drywall knife. Make sure the thinset is flat and smooth so the tile will lie flat. Let the thinset dry completely.

Install Tile

Mix more thinset and apply it evenly to the wall with a notched trowel. Set the cleaned tiles into the thinset, aligning the grout joints with the existing tile. Let the thinset cure, 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 on the manufactures directions.

Caulk Tile Joint

Once everything 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."