Waterproof & tile existing rendered wall

3simon · Oct 01, 2020 2:49 pm

Our bathroom wall is rendered & painted on top of masonry substrate. We want to waterproof the wall of the shower area to 1.8m and above and re-tile.

Just wondering if you guys can help me out with two questions I have:
1) What is the sequence of events for waterproofing and tiling rendered wall? Is it as simple as apply waterproof substance to existing rendered wall, and tile on top of it using adhesive? I was referencing the james hardie wet area construction guide, and was slightly confused by the application of vertical corner flashing (see attached pic), given I don't plan on putting in villaboard lining, the vertical corner flashing doesn't apply to me right?

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2) The guide also mentioned the use of PVC angle for the wall to floor joint (see attached pic below). Does that apply to my scenario? Would applying waterproofing substance to the rendered wall and floor joint achieve the same purpose?

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Thanks!

chippy · Oct 01, 2020 8:40 pm

Hey Simon. First thing you need to do is make sure all the render is sound ie nice and solid, straight and flat.
Once you have done that you do the waterproofing.
As a minimum you need to do a silicon bond breaker bead on all internal corners. Personally I use bond breaker tape as I really want to make sure the waterproofing is fail proof.
To apply the tape you paint the waterproofing along an internal corner then cut lengths of reinforced tape and press it into the wet waterproofing (half on each wall) then paint it in with more waterproofing.
You need to do all corners.
Once it's done let it dry and do another coat of WP and you are done.
The bond breaker prevents the WP tearing if the us any movement in the underlying structure.
If you are doing your own waterproofing take your time. It really is the most critical step in the whole bathroom renovation.

3simon · Oct 01, 2020 9:21 pm

chippy

Hey Simon. First thing you need to do is make sure all the render is sound ie nice and solid, straight and flat.
Once you have done that you do the waterproofing.
As a minimum you need to do a silicon bond breaker bead on all internal corners. Personally I use bond breaker tape as I really want to make sure the waterproofing is fail proof.
To apply the tape you paint the waterproofing along an internal corner then cut lengths of reinforced tape and press it into the wet waterproofing (half on each wall) then paint it in with more waterproofing.
You need to do all corners.
Once it's done let it dry and do another coat of WP and you are done.
The bond breaker prevents the WP tearing if the us any movement in the underlying structure.
If you are doing your own waterproofing take your time. It really is the most critical step in the whole bathroom renovation.

Thanks Chippy, that's really clear and useful tips!