Waterproof Membrane?

Wow,

I think if you’re going to fix it, may as well do it properly.

Rip out everything and start again


Sent from my iPhone using Tapatalk

+1 to JB1. only way to fix it to todays waterproofing standards in to rip it out and start again. There is no way to effectively waterproof the entire showerbase/shower walls from that position.

"Rip it all out" is not quite right.
What they mean is you need to remove wall tiles and floor tiles, apply waterproof membrane (usually applied by painting - it's thick) to a certain height on all shower walls above the floor, repair the floor, apply the same waterproofing membrane on the floor and then finally tile.
You need to do some more research on the current rules. Check the NCC. Not sure if you are "permitted" or "prohibited" from doing this sort of plumbing work.
I've done it myself a couple of times but some years ago because I couldn't find a reliable and honest plumber/tiler to do it. If you do it properly and take your time you'll probably do a better job than most tradies anyway. A pity but that's the way it is.

....and not just the tiles. You will need to reline the shower walls with new cement sheeting.

Step 1 is to rip the entire shower recess out so all you see is the framing and go from there.

Plenty of options to consider for the base including a poly marble base that if installed right (mortar base with zero air bubbles under the base) will out see the life of the house.
Is it on a timber floor?? as your likely to need work on this before anything else.

Get a copy of the standards (good to know what the standard is anyway) or hire someone that knows what they are doing for the waterproofing as if not done right, the work will be all for nothing and you will be back at square 1 ripping it all out again.
There is good reasons why there is a minimum standard, and requirements to be licensed for applying waterproofing as there are plenty of so called experts that know SFA or think they know more than the standards only to have the job fail in as little as weeks, months or premature years down the track. Experience in this area with 2 failed 5 year old showers, done the demo and really easy to see why...and the original guys were licensed!!!...which is why you need to know the standards so you can spot a substandard job.

If you looking for a cheap total shower cubicle referb, a few options that are almost child proof such as the poly marble preformed base and 1 piece laminate or acrylic (plastic) wall panels

Being Perth it is most likely solid brick and concrete floor, hopefully the OP will be back to confirm.