How to Seal the Joints in a Shower Surround Before Tiling

The material that you construct a shower surround from, such as backer board, requires a small gap between the boards to allow for flex and movement. This gap or joint requires sealing before tiling is started to help prevent moisture from getting into the walls. Sealing the joints in a shower surround before tiling is a two-step process. Allow 24 hours between sealing and tiling to let the joints dry.

Things You'll Need

• Tile thin set
• Margin trowel
• Fiberglass mesh tape

Instructions

1. Fill the joints between the boards in the shower surround with a small amount of tile thin set mortar. Scrape the mortar over the seams using a margin trowel. Keep as much of the thin set in the seams as possible and scrape away the excess from the boards.

2. Press fiberglass mesh tape into the thin set, covering the joints. Begin at the top of the surround, and smooth the mesh downward with your fingers as you unroll toward the bottom. Run the edge of your trowel over the mesh to press it firmly into the thin set and eliminate any trapped air bubbles.

3. Spread a second layer of tile thin set mortar over the fiberglass mesh to create a smooth, even surface. Gently taper the thin set on the sides of the mesh into the boards by scraping the edges of the mesh with the trowel at an angle. Run the flat portion of the trowel over the thin set to smooth it out. Allow it to dry before tiling.

References

• Hometime How To: Wall Underlayment
• The Floor Elf: Installing Cement Backerboard for Tile in a Shower