Tile Installation: Backer Board Around a Bathtub

Finally – the tile backer/tub lip problem resolved

Does tile backer board lap over the bathtub lip, or sit on top of it? It’s a question that’s puzzled first-time bathroom remodelers for years. This article explains the correct method.

By the DIY experts of The Family Handyman Magazine

Cement board detail

The best approach when installing cement board or other tile backer around a tub is to keep the cement board out of the lip area. Apply it to the wall with the bottom edge about 1/4 in. above the lip of the tub. Then apply a generous amount of thin-set to the bottom tile and position it 1/8 in. above the tub. Fill the gap between the tile and the tub with caulk.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Caulk gun
  • Cordless drill
  • Notched trowel
  • Hammer

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Thinset mortar
  • Caulk
  • Tile backer