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Hi all. Hoping for some guidance on this one.
Pictures provided are 1 showing the problem area and the other the OK area.
Looking to find a suitable product to help reduce or stop any rising damp, sweat or moisture before I replace my flooring.
I have a 30-year-old concrete slab that is ~30m2 that was poured before the rest of the house slab was. This is my kitchen / dining area. It seems to hold or produce moisture between the concrete slab and my temporary flooring (of 5 years now) which is 9mm thick carpet tiles (with a rubber base).
Regardless of the weather or season, it has moisture or damp appearance, which then leads to mould under the carpet tiles. And even with the carpet tiles lifted, the concrete appears damper than the other areas of the house.
It only occurs on the kitchen/dining slab and has no sign of issue anywhere else in the house.
I am planning to install the QEP 3mm silver laminate underlay and laminate floorboards to replace the temporary carpet tiles solution, BUT BEFORE I DO, I want to treat the concrete slab before I go ahead with the work.
I've looked at damp proofing products such as 'Dunlop 4L Damp-Proof Waterproofing' as well as general waterproofing, but not sure how I should go about it. Noting I'm not sure if it's a breathing issue in the slab or a moisture seeping issue, or something else altogether.
Should I go with water proofing or damp proofing? Or both, or something different again?
Will minimal recommended coat/s be enough or do I consider more?
I will be scrubbing the concrete clean first. Should I use non-harsh chemicals, or do I need to go something stronger?
Look forward to your suggestions.
Thanks. Doug.
Welcome to the Bunnings Workshop community @dougym. It's terrific to have you join us, and many thanks for your question about moisture-proofing a floor.
I suspect it would be moisture being wicked up through the slab and presenting itself under your tiles. I would suggest using Dunlop 4L Damp-Proof Waterproofing and following the directions on the number of coats required. The specified number of coats offers the best performance, and more coats than the recommended does not offer better protection and, in some cases, can cause the products to fail.
The reason for believing it is moisture wicking up through the slab is that if it was a waterproofed slab or there was no moisture in it, there's no reason why moisture would be accumulating under the tiles unless you've dropped water onto them.
I would not use any particularly harsh chemicals to clean the slab. I would suggest using a mild soap mixture with water, such as dishwashing detergent. Ensure you flush off the area with fresh water after cleaning.
Please let me know if you have any questions.
Mitchell
