Waterproofing Concrete block wall on one side

Dubh Geannain

Hi. We've got a lean-to over our side door that I'd like to waterproof a bit more. Our neighbours are slightly higher than us such that when it rains particularly heavily water seeps from their footpath through the concrete block wall separating our houses. I'd like to seal our side just up to one or two blocks high.

Firstly will this be bad for the blocks in that the water will no longer pass through them, so they'll take longer to dry out? They're never sitting in water really except when a heavy rain comes and it builds up a little bit before draining away on the neighbours side I assume. It's not that it drains though our side, it's barely even a trickle.

Secondly, if it's okay to do it. What would be a good sealer? Is fibreglass the only way to go or are is there a less noxious alternative?

10-10-20

Silicon-based Water Seal might be the best option here, but I don't know what the general opinions are on this:

https://www.thompsonsweatherproofing.co.uk/waterproofing/water-seal/

I'd imagine that the water could still seep though the lower parts of the block, but this should prevent much of the capillary action.

Dubh Geannain

Thanks. That was the stuff I was looking at but wondered if fibreglass was superior and recommended. Happy enough to give that a try though first.

Lumen

It sounds like you're trying to tank it.

https://www.permagard.co.uk/advice/wall-tanking-guide

Dubh Geannain

https://www.boards.ie/discussion/comment/117993651#Comment_117993651

Sorry for the late response. Thanks for that.