The new tub rim upturn lip has chipped and cracked a little. To install the wall tiles, which option is better?

  1. Install the tile backboard (is it cement board) in front of the upturned lip and overlap it. Then install tiles over cement board. Question: the face of lip is 1/8"-1/4" in front of face of studs. Would the cement board be bent? and is it a tight overlap at the lip since there should not be screws too close to the lip or going thru the lip?

  2. install the tile backboard above the lip so the face of the board flush with the face of the lip. Then install tiles over the lip and board?

enter image description here

  • The lip looks thick there or I am not thinking correctly but #2 sounds better to me, put water in the tub when you put your calking to seal this will pull down a tiny amount and make a better seal. – Ed Beal Aug 20 '19 at 23:27

Option two is the way to go. You don't want any angle space between the studs and the cement board. Secure the cement board firmly to the studs flush with the edge of the tub lip and seal the seam with caulk. Then install your tile over the cement board and face of the tub lip. Then grout and then seal the bottom row of tile where it meets the tub with caulk.

  • I was thinking that lip looked thick and not a thin seal.+ – Ed Beal Aug 20 '19 at 23:28
  • If you zoom in, it appears to be about 1/4 inch but then my eyes are 70 years old..lol – JACK Aug 20 '19 at 23:42
  • If we do option two: Can the RedGard (liquid applied waterproofing) be painted over the tub lip and cement board to create a waterproof membrane? (the RedGard goes on the tub side of the cement board, correct?) If we seal the seam with caulk, does the tile mortar adhere to caulked area? If we shim behind the cement board, can we go with option 1? – user105071 Aug 21 '19 at 13:24
  • I have not used RedGard but yes, it would go on the tub side of the cement board. If you're using caulk, you would just caulk the seam. Then use tile mortar/adhesive from the seam up and a bead of caulk from the seam down to the lip of the tub. – JACK Aug 21 '19 at 13:52
  • Would the tiles then drape in front of the tub lip? What should be used to adhere the bottom of tiles to the tub lip ? Thanks a lot for the advice – user105071 Aug 21 '19 at 16:36

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