Tiles have seams. Lots of them. All those grout lines in your shower, that thin line between each and every tile in your shower, all let water pass through them. Water goes through the grout lines, past the tiles, and into the wall. If the wall material is porous, it stays there and incubates mold. Ew.
This shower was built the really old fashioned way with lath and plaster aka “wet wall” (contrast to the Drywall we use today). The workmen would mix plaster with water into a paste and smooth it onto the walls. That was your wall. There is some wire in the middle to give it strength but it’s plaster and plaster absorbs water.
The shower pan was also very old school. There is better technology for building shower pans now, such as the Wedi system (see video).
When I carried that old moldy shower pan out, the owner held her nose and said “There goes the smell. That was it.”
And out it went!
Now the rebuilding is easy. It’s what we do. First the framing modifications for the recessed soap dish.
Then the backer board.
Then we need to patch the floor. You see the existing tile doesn’t make it to the shower pan. (Sorry the tile is covered in this photo, but you can see the gap. The sub-floor is exposed.)
We needed to replace the center tile completely, and put some small pieces on either side. Of course there is some new sub floor installed under there, glued and screwed, tile backer board (Hardibacker).
And that’s it. We’re done!
Now the owner has a nice smelling, brand new, clean shower ready to use.