What shower wall compound to use?

Question

I've been doing a DIY on my shower which required me to pull out the walls and to check behind them for water issues. Have had mold treated and plumber come out to properly check the pipes.

My issue is I think I've used the wrong joint compound on the new used to join them with the existing one. I have used

https://www.bunnings.com.au/gyprock-csr-20kg-base-coat-45_p0731156

Looking over it again now I believe I should have used the purple one. I have only done one coat at the moment and wanting to know if I have to sand down as much as possible and add two layers of the proper wet area coats to fix what I've done or does it all have to come out?

MitchellMc · Answer

Thanks for the update @Kross.

It sounds like you've got things well in hand. Just be particularly careful when sanding around the joints so you don't damage the face of the plasterboard.

Keep us updated on how you go, and please reach out if you have any questions along the way.

Mitchell

Kross · Answer

Hi @JacobZ

Thanks for the help! The area will be fully enclosed in waterproofing. Current plan is to sand down some of what I have and add two coats of the proper stuff before prime and waterproof

JacobZ · Answer

Hi @Kross,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Can you clarify exactly where you've used the standard base coat? Is it within the direct wet area of the shower, and will it be completely covered by the waterproofing membrane before the tiles are installed? Or is it in an area that won't be fully enclosed by a waterproofing membrane?

Realistically, if the base coat is going to be completely encapsulated behind a correctly installed waterproofing membrane, it shouldn't ordinarily be exposed to moisture. It's not ideal, but it is also not likely to cause issues under ordinary circumstances.

That said, wet areas need to be constructed as a complete system in accordance with the requirements of the plasterboard, jointing compound and waterproofing manufacturers. If you are using Gyprock Aquachek, it is a requirement within their system in order to be covered by the manufacturer's warranty.

I would give sanding out the base coat a try. As long as you take care not to damage the plasterboard too much, it is possible, given enough time. If you wanted to give it a try, I'd suggest using an orbital sander with 120-grit sanding paper.

You can also sometimes use the jointing tape to help pull out sections of plaster if you can expose an edge. Scraping with your jointing knife can also often help.

Also, make sure you wear a mask, isolate the area and clean up regularly, because there will be a lot of sanding dust.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob