How to fix water ingress?

Question

Hi!

I’ve had an issue of water ingress into a section of wall.

I believe this issue has been here for a while. I removed the damp gyprock. Replaced the window believing that may have been the issue. However after removing the bottom tiles, it now is clear that the water is seeping through the bottom block.

there are some cracks in the render on the outside. And I have confirmed water isn’t coming from the roof.

MitchellMc · Answer

I think this image paints a pretty good picture for us @Sweequew.

The red area shows water getting into the wall at the sill and running down, and the blue shows rising moisture which is getting in lower.

Interestingly, in the red section, there seems to be moisture right across the underside of the sill. Is the sill painted underneath it? Any cracks there? That might not be an adequate drip ledge and rain could be getting up under it. Obviously, that crack isn't helping.

Does that dampcourse line match up with your internal floor height?

Mitchell

Sweequew · Answer

lightning fast response! Thanks mate.

I’ve attached another pic. The line in the render from the outside in the floor level on the inside. And the house is concreted all around.

Could ground moisture or drainage still be a factor? I’m all ears

MitchellMc · Answer

Welcome to the Bunnings Workshop community @Sweequew. It's sensational to have you join us and many thanks for your question on water ingress.

If the moisture is coming through the bottom block, you’re on the right track focusing on the wall base rather than the window or roof. Cracks in the render can definitely let water in, but more often the bigger issue is water getting trapped or sitting against the wall and then being forced through the masonry.

One common cause is the render or external ground level bridging the damp-proof course, which allows moisture to bypass that barrier and wick into the wall. Even if the DPC is there, it only works if it’s exposed and there’s a clear gap above ground level. It’s worth checking whether the render runs down too far or if soil, paving, or garden beds are built up against the wall.

It’s also worth noting that the dampness appears to line up with the crack externally, which suggests that crack is at least contributing to the ingress rather than being purely cosmetic.

I’d start by cutting back or removing a strip of render at the base to expose what’s going on, and at the same time check the drainage. Make sure the ground falls away from the house and water isn’t pooling in that area. Once that’s sorted, repair the render cracks properly and allow the wall to dry out before closing it back up internally, as blocks can hold moisture for quite a while.

Please let me know if you have any questions.

Mitchell