Should the plastic walls of a shower kit have air bubbles?

Question

We had a corner shower installed awhile ago in our basement. The kit came with thin acrylic walls that were glued to the waterproof gyprock behind. However, there are air spaces between the lines of glue which allows the walls to move in certain places. We have been having a problem with this shower leaking and were wondering if this movement was perhaps breaking the seal that the caulking makes between the floor of the shower and these walls. The shower sits on a raised wooden platform built for the base of the shower, but there is also a bit of movement in the floor as an adult is in the shower.

I had heard from someone that on these showers you did not need to caulk the place where the acrylic walls meet the base, but that just seems wrong as I would expect mould to grow with pooled water behind the walls.

We were thinking of replacing the walls with a one piece firm acrylic piece and keeping the existing floor and glass sides and door. Any thoughts on the best way to fix this leaky problem?

Leak Location

Answer 1

You are absolutely right that the floor will move independently of the walls. The movement when an adult steps in is not as much as a full bath of water, say, but it is still enough that you need a flexible seal of some kind to avoid water pooling and mould growing.

I asked a similar question which @ChrisF answered very well which suggested that caulk should be flexible enough to cope. That is what I did, and so far I have had no leaks (I have taken the panels off to check every now and then)

Answer 2

Proper shower systems should have a lip behind the base. Better systems apparently also have a gasket. So, in theory, no you don't need to caulk them. Bad ascii diagram:

 ++  +
 ||  | <----+ bottom of wall panel
 |+--+
 +---+
     | <----+ shower pan
     |
     +--------------------------------+

The idea is that any water that gets behind would shed down the lip and into the shower pan.

The catch is a) I'm not sure all shower systems are this well engineered and b) showers are more than water...there is dirt, grime, soap, hair, dead skin, other nasty body and soap residue. So, yea, it will still get grimy and is why most people still caulk it.