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Discussion Starter · #1 ·
I've got a fiberglass shower pan in a home built in 1968 and one corner shifts ever so slightly when I'm in the shower. The rest of the pan is solid. Movement is probably 1/16" or so.

I had regrouted the lower half of this shower, and a few months after the repair had a leak reappear. Luckily my son in law was with me when I inspected it and we learned that when I was standing in the shower the lowest run of tile in that corner had cracked free of the wall grout and was floating up and down with the pan. No good.

Anyway - I've pulled all the old tile and plan to regrout without grouting the bottom 1/3 of the tile that overlaps the pan edge.

Two questions:

1. What kind of caulk or sealer should I use on the interface between the tiles and the shower pan to prevent the tiles from being pulled downward again?

2. Maybe should I put a sheet of some thin but durable plastic between the tiles and the pan edge so I can properly grout the edges of the tiles without them getting stuck to the pan?

· Retired Moderator
25,780 Posts
That wall is failing----grout is not waterproof----it's just not---water will get through to the backer board --that should be waterproofed---

Sorry but I believe the shower needs a new pan and walls---

· Tileguy
10,718 Posts

You seem to be of the opinion that grout is your issue. It is not, maybe.

Assuming there is no objectionable wall damage...I would remove the tiles that are flexing. Then inject some construction adhesive behind the pan. Stay off of the pan for at least twenty-four hours. The construction adhesive should bond to the subsurface and if you inject enough, it would also bridge any gap that is allowing the movement of the pan. Use PL-400 adhesive.

Then reapply the tiles being careful not to again attach them to the pan, only attach them to the wall material.

Then when all has had time to "set", re-grout the tiles but don't grout at the wall/pan juncture. Use caulk at that juncture.

If the wall tiles are grouted to the pan all-around, remove that grout and caulk that juncture also.

I see no need to demolish anything and re-do it at this point.

Should this also create a small void behind the tiles as they cross-over the lip and arrive at the pan it's no big deal.

Tile and grout are not waterproof and moisture can always get into a wall such as that one.
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