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How do you waterproof a bathroom?

waterproofing.jpegBefore you start the project, you may like to check with your local council about any licensing requirements for waterproofing.


According to NSW Fair Trading, to get a licence or certificate to do waterproofing, you need one of the qualifications listed below:


  • CPC31411/ CPC31408 Certificate III in Construction Waterproofing
  • BCG31403 Certificate III in Waterproofing (General Construction)
  • Qualification 90464 Certificate III in General Construction (Waterproofing) TAFE course #8126.


To find organisations that offer nationally recognised training, go to and search by the course code or name.


For laundries, if your laundry walls are plasterboard then they can be painted with a suitable bathroom paint which includes a mould preventative. Typically walls are not waterproofed, however, you can continue the floor membrane up the wall if you wish to do so.


Some videos that should be helpful can be found below. 




If the surface is slightly gritty, I would recommend using Gripset Betta Prep Coat Waterproofing Primer before applying the Gripset Betta- Under Tile Waterproofing Membrane. This primer will ensure the membrane adheres correctly to the surface.


There are also some helpful all-inclusive products for shower recesses like the Crommelin Shower Waterproofing Kit. The kit provides all materials and instructions to successfully waterproof a shower recess prior to tiling. - MitchellMc


We used paint on waterproofing. Once the screed has fully dried, vacuum it well and paint over some primer (use one that is compatible and the same brand as the waterproofing) then paint on the waterproofing. I used three coats in the shower and two coats on the rest of the floor. You need to silicone the edges first and use waterproofing tape around the edges. Bunnings have heaps of great videos that go through the steps. Also don't forget to seal the grout afterwards as it does make a big difference to how clean the new tiles stay - Carmel99


Any plastic sheet videos you might see out there are all US based. That method is not used here, at least not on any job I have ever seen. Vacuum any dust, and prime with an acrylic based concrete primer (not a paint primer). Apply extra to areas that are soaking it in too fast.


My advice is don’t use Bondcrete, as it dissolves back to a liquid if it gets wet - I think it is just PVA glue, with a genius brand name.


Apply a fillet of compatible sealant to all corners and crevices beforehand. Use your finger to smooth it to a small radius, 5-6mm. I'm not sure if silicone is right for this. I use an SMP eurethane such as Solarflex ($21/600ml sausage), but you can use Flexiseal ($15/600ml). Both are paintable, but the SMP has the edge in sticking to the widest range of products. I use it for many, many tasks. - ​​dejayajay



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