Hi I have an area at the front of my house which has large limestone flags where the joints are cracking and allowing water ingress into two rooms which are under the flagged area. I would like to re-point the flags with a waterproof jointing compound. Are there any readymixed compunds available or is it a case of making a sand/cement mix myself. if so what should i use and in what ratios in order to get a good waterproof seal?
cheers
Waterproof pointing diy
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Tony McC
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We wouldn't ever rely on waterproof jointing to prevent moisture ingress to sub-surface rooms. Even the very best mortar products/additives cannot guarantee 100% watertightness, and you need only the slightest movement of one flagstone to cause a crack in the jointing and hey ho! You're back to square one.
The correct methodology would be to install a waterproof Damp Proof Membrane beneath the paving, then re-lay said paving on a waterproof bedding material with waterproof jointing, if so desired, but, in all honesty, it's the DPM that provides the security of watertightness, so I'd be inclined to re-lay using a more conventional method.
You can buy waterproofing additives for mortar, but, as I've said, it will be only a matter of time before the jointing (not the waterporoofing) will fail.
The correct methodology would be to install a waterproof Damp Proof Membrane beneath the paving, then re-lay said paving on a waterproof bedding material with waterproof jointing, if so desired, but, in all honesty, it's the DPM that provides the security of watertightness, so I'd be inclined to re-lay using a more conventional method.
You can buy waterproofing additives for mortar, but, as I've said, it will be only a matter of time before the jointing (not the waterporoofing) will fail.
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