How should I prepare these ensuite walls for waterproofing?

[lmcguinness96]

Hi there,

I'm based in SA and I've just demolished my ensuite (which for reference is very small, 3m x 1m). Plumber has been in to chase the walls and move some of the plumbing and now it's onto preparing the walls for waterproofing. I'll be waterproofing myself (which I'm fully aware you may not all agree with), so I just want some advice on preparation of these walls before waterproofing. I'm hesitant to go with Villaboard as I'll lose approx 20mm per wall between the furring channels and the sheet in an already small space, so leaning towards rendering/plastering.

What do I need to do specifically for patching the chase work (which at it's deepest points is up to 70mm), and also to smooth the rest of the walls (the render that remains seems really sturdy and no drummy spots)?

Shower pipework

Vanity pipework

[EricL]

Hello @lmcguinness96 

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

If your budget can afford it, I propose getting a professional to render your wall back to a fine finish. Using render means that you will not loose a great deal of wall space and your waterproofing will go on flat and level. However, if you wish to apply the render yourself, I've placed a guide below and a recommendation on what product to use.

Just a friendly reminder that waterproofing must be installed by a trained, registered agent as it will need to be sighted and signed off.

Here is a handy step-by-step guide: How To Render

I suggest having a look at using the Dunlop 20kg Fine Coat Render to cover your damaged walls. 

If you have any other questions we can help with, please let us know.

Eric

[lmcguinness96]

Thanks so much for the reply Eric! I really appreciate it. 

With regards to the deep chases left by the plumber, I'm not sure the Fine Coat Render will work as it can only be up to 10mm thickness. Is there a product I can use for those chases before using the Dunlop Fine Coat Render over everything?

[MitchellMc]

Hi @lmcguinness96,

You should use mortar to fill those deeper areas and then skim coat over them with the render. You should build up the depth with a few coats of mortar instead of one, as that will prevent it from slumping and falling out of the void.

Mitchell

[lmcguinness96]

Makes sense thank you Mitchell. Any protection required around the copper pipes before using the mortar? I've read around the place that the cement in mortar can be corrosive to copper so some people recommend taping the pipes with gaffer tape?

[MitchellMc]

That's only really an issue if there is an active leak and the mortar becomes wet, allowing it to leech alkaline compounds @lmcguinness96. Once the mortar has set, there's little to no risk of it interacting negatively with the copper. However, it doesn't hurt to wrap the pipes with tape, or even pop some pipe insulation on them to distance the mortar from them.

Mitchell