Tiling a Shower

My great-aunt's shower needs to be retiled. The house was built in the '50s, and while it is very sound, the shower is not. The tiles are about 5" square, and the bottom few courses are so loose you can push them back into the wall if you're not careful, which is what happened to one. I'm thinking about retiling the bottom 1/4th of the shower, because that's where all the loose tiles are. What I can't figure out is behind the tiles there is nothing but a void a few inches deep. How did the builders get the tiles installed in the first place? The shower looks professional, with all the tiles even and nicely spaced, so I can't figure out how they built this. Second, how do I re-do this with nothing to stick the tiles to? There is no mortar on the back sides of the tiles (nothing to stick them to), just mortar around the edges of them. I'm pretty confused here. Anyone familiar with this? 

Edited by CrestonM - 04 Sep 2018 at 10:37pm

Creston, X3 on what Pat is saying but I would respectfully add take out the shower base also then install the durock. After that put in a good thick one piece liner 18" up the wall and hard pack damp sand to support the floor tile and a brush on water proof membrane on the remainder of the durock. The tile has to have a solid backing if it is going to last. You need to tear out and redo the entire shower or you will be back in there patching again.

Hubert (Ga)engine7 wrote: Creston, X3 on what Pat is saying but I would respectfully add take out the shower base also then install the durock. After that put in a good thick one piece liner 18" up the wall and hard pack damp sand to support the floor tile and a brush on water proof membrane on the remainder of the durock. The tile has to have a solid backing if it is going to last. You need to tear out and redo the entire shower or you will be back in there patching again.

I agree 100% do not tile over drywall even the mildew resistant green or blue. It’s not waterproof nor does it claim to be. If you have to replace tile old stock and new are hard to match up on color and size.
Make sure everything is dry clean and solid before you go back.

wear a mask if/when you mess with that asbestos

Or you could just hire Jay's "contractor" stepson to do the job. Jay might even pay you a little bit to get him away from that area for a while. 

Hubert (Ga)engine7 wrote: Or you could just hire Jay's "contractor" stepson to do the job. Jay might even pay you a little bit to get him away from that area for a while.

Why tile? The plastic tubs and shower surrounds are a lot likely to ever leak and there are not joints every 4" that need cleaning and or redoing every couple years.

the "STUFF" hanging behind the wall might not be asbestos........ It might be drywall that got wet and fell apart... paper and fluff is all that's left... There was SOMETHING on the studs that the tile were glued to  in the beginning... I bet it was drywall..  If you redo, get cement board and screw it on... better than green or blue drywall.

Judging by the homes age and your description it is most likely drywall used for the tile backer and a vinyl mastic adhesive to bond the tile to the wall. Assuming 1/8" grout lines, a non-sanded grout filled the gaps between the tiles. This grout will lose its bond to the tile over time allowing water behind the tile and destroy the drywall. I'll take a wild guess that the shower drain cover says Fiat on it. If so, this may be a terrazzo base that has a metal frame around it that won't tolerate exposure to water for long before it rusts out and then allows water to get under it to damage the subfloor. At the very least, before you begin the repair work plug the drain and fill the base with water to the top of the threshold to confirm it is not leaking.