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I’ve got a late 1960s high set house, so the slab doesn’t have positive side waterproofing (pretty sure the original owners sorted the slab themselves).
The lower level isn’t legal height, but I’ve built another spare bedroom downstairs. Timber framed, gyprock sheeting, insulation. When the base plates for the stud walls were put in I didn’t put waterproofing down, so there is water coming up through the slab. The side walls have bitumen paint on them that seems to have worked. I initially did the same for the flooring, but with the rains back in early 2022, that was pushed up and had to be removed mechanically. Since then I put down Davco K11 - an alkali reactive cementitious waterproofing product. After Alfred came through recently, there was minor flooding coming through where the studs were drilled into the slab and under the studs. I know I’ll have to remove the baseplates of the studs and replace them.
I’m after advice on waterproofing products to use, whether or not the baseplates can be steel studs or I should go with timber again with adequate damp proof treatment between the timber and slab, or just any general advice. Waterproofing products would need to be negative side.
Thank you in advance!
Hi @boxer-brass_09,
That would be Drizoro Maxseal Super. You'd need to speak with our Special Order team in-store, and they'll try to order it in for you. It's a trade-level product and not currently available for Special Order. Remember that to have its crystalline effect work, it needs to be applied over concrete, not a previous membrane.
Mitchell
The Maxseal Super is a standalone product @boxer-brass_09. However, you could potentially apply the 1-Komponent over it.
MaxPlug is primarily designed for active leaks and patch repairs. I also don't believe it is a crystalline growth compound, as I couldn't find a reference to that. The Drizoro technical team advised that the Maxseal was the preferred product for your circumstance.
Mitchell
Thanks @MitchellMc - much appreciated!
Am I over complicating this by potentially using all of these products, or are they necessary due to the complexity of the issue? How do they compare to say Dunlop Damp Proof, or something made by Crommelin?
I’ve taken up the baseplate of one of the walls and found the problem area/s. The main one being where the brick wall meets the slab (the wood was blackened with mould - the area has since been sprayed with Selley’s mould killer), and there were a few very small centipedes running around). The black you can see on the bricks is Sika BE. That section of the wall is incidentally where the external concrete drainage gutters meet the house from the very steep driveway and run along the front of the garage,
There’s no evidence of water coming up from where the concrete screws are drilled in the the slab.
Hi @boxer-brass_09,
Given the amount of work you're doing, you should do it once with the correct product. That being Maxseal Super, if water is pushing up from below. You have quite a serious problem, and something like Damp Proof isn't capable of resolving it. That's more used for rising damp, whereas you have water penetration under pressure.
Mitchell
Hi @boxer-brass_09,
As mentioned earlier, it would be best to speak with a builder or waterproof expert regarding these questions, as they fall outside the typical advice we can access from the manufacturer. When waterproofing a slab, all penetrations through it should be sealed. That could be done with a polyurethane like Sikaflex 11FC.
I've been advised that Sika 1 Komponent would not be the best product to use on a flat surface that has pressurised water beneath it. It could be fine to use in these circumstances, but Sika can't confirm entirely due to the unknown variables, like water pressure.
Mitchell
