How do I waterproof shower?

[poodsie]

I'm looking for advice on how to waterproof our bathroom wall. We've moved the shower from one side of the room to another which means it will end up in an area that was previously painted (RHS in the photo below)
I've purchased the Crommelin Waterproofing Membrane Surface Primer and Crommelin Shower Waterproofing Membrane and from what I am reading, they're suitable for the rendered wall (LHS, where the shower used to be). However, I am unsure whether the primer is suitable for the painted part of the wall of the future shower? Do I need to remove the paint and white set first?
The idea is to waterproof and then put wet wall panels on top.
Thank you!!

New shower in are marked out in red

[EricL]

Hello @poodsie 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your shower.

I suggest finishing all your concrete works and rendering before you begin planning your waterproofing. Both the render and concrete will take time to cure especially in an enclosed space. This would also be a good opportunity to finalize your plumbing works, because once the water proofing has been applied, it will no longer be possible to cut into the wall for additional plumbing fixings. In regards to the painted wall, it will have to be stripped off so that the primer can properly grip onto the surface of masonry wall. I suggest using a Josco 75mm Strip-It Wheel to remove the paint on your wall. 

Just a friendly reminder that you'll need a trained and certified waterproofing agent to apply and seal your bathroom as it will need to be sighted and signed off. 

Let me call on our experienced members @Nailbag and @Dave-1 for their recommendations.

If you need further assistance, please let us know.

Eric

[Dave-1]

Good Evening @poodsie 

I have been thinking of those type of wall panels as well, and was thinking about what type of waterproofing ect would be needed.  I know you need to get the waterproofing signed off by someone accreditated for the install. I would hit up the people who you will be engaging and see what they say as a first step. Otherwise I would be following @EricL 's suggestions I had not considered removing the paint from the wall beforehand. 

Dave

[poodsie]

Thank you both, @EricL and @Dave-1  
I should have mentioned - the plumbing and the rendering is all done. The picture I provided was taken right before - it's just clearer to see what my question was about on this photo, which was taken prior. Apologies for the confusion.

The wall will need to be waterproofed before the wet wall panels can be installed (which we will do ourselves) so the issue we had was just those painted walls as I didn't think any primer would stick to it. It sounds like the Josco 75mm Strip-It Wheel is the way to go. With that in mind, does a new coat of render need to be applied or can the primer and membrane be applied onto the bare brick wall?
Thank you all so much - it's really appreciated!

[EricL]

Hello @poodsie 

Thank you for providing that extra bit of information in regards to your bathroom project. I would suggest rendering the brick surface in order to have a flat uniform finish when the waterproofing is applied. This will also have the added benefit of having a level surface when the panels are installed. Yes, the Crommelin Shower Waterproofing Membrane can be applied to a brick surface.

If you need further assistance, please let us know.

Eric

[Nailbag]

Hi @poodsie 

If this was my project I would be fixing a 3-6mm cement sheeting to the wall to provide a consistent surface material and facing. Then tape the joins and apply the waterproof membrane in accordance with local guidelines. Take photos of each step as this will be required for any potential future insurance claims as you're applying this yourselves.

Nailbag

[poodsie]

That’s actually a really good idea and would remove the need for the removal of the paint, correct? 
Hadn’t considered insurance - this is really helpful. Thank you!

[EricL]

Hi @poodsie 

I would still suggest removing the paint to make sure that the adhesive for the cement sheet goes onto the rendered surface rather than the painted surface. 

Eric

[poodsie]

This is all so very helpful!! Thank you everyone, truly appreciate all the help!