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I have just installed brand new windows and it has exposed a 30mm gap between the bottom of the window frame, outside on our verandah. I was going to fill it in with black grout however I'm worried this might still allow some water through. Any ideas of how best to tackle this?
Welcome to the Bunnings Workshop community @Pez-disp. It's amazing to have you join us, and many thanks for your question about sealing a window frame.
To start, remove any deteriorated sealant that has pulled away from the slab, as this would have previously sealed it to the old window frame. Next, apply a gasket of Sikaflex 11FC between the slab and the new frame. Sealing this gap is important because, if left unsealed, water can travel from the slab, down its edge, and under the window frame.
Once that’s done, I recommend painting a waterproofing membrane over the exposed edge of the slab, extending over the Sikaflex and up to the window frame. This will provide an added layer of protection against water ingress. After that, you can safely grout the area, knowing it is properly sealed beneath.
Please let me know if you have any questions.
Mitchell
