How to fix water sloping towards house?

dr_harika

Hi, I have a sloping block and some water is getting between the concrete and the house. This is best illustrated by the condensation drain on the nearby air-conditioner (see photos).

You can also see the concrete path seems to have sunken close to the house as you can see a gap between the render and the concrete path. 

I don't think I can get that side of the slab lifted by injection grouting because when enquiring, I had too many services nearby. (That thick pipe is gas, and there is stormwater and sewerage in that proximity) although I'm happy to be proven wrong. 

As a quick fix, I put a bead of polyurethane on the concrete to act as a lip. This worked for a while but the polyurethane has weathered in some locations and I want a better fix. 

To be clear it's not just the aircon water I want to fix, it's any rain or garden watering that makes it onto the concrete path as some of it no doubt makes its way into the gap which wouldn't be good for foundations etc. I'm not noticing water issues inside (there is a room behind the wall partly below ground) 

How should I address this? 

MitchellMc

Hi @dr_harika,

How long did the polyurethane last before it started to weather? If it held up for a while, that’s a good sign the basic idea was sound; it just needs a more durable execution. If you clean the joint out properly and reapply a wide, continuous bead of a high-quality sealant such as Sikaflex 11FC, shaping it into a small cove (rather than just a thin line), it should do a much better job of blocking water from getting between the concrete and the wall.

That said, a longer-term fix would be to combine sealing with a small concrete barrier. Once you’ve resealed the gap, you could set up simple timber formwork around 50mm out from the wall and pour a 50mm x 50mm concrete edging down the length of the problem area. Think of it like a shallow gutter or kerb. When water runs towards the house, it’ll hit that small barrier and redirect away along the path instead of seeping down the wall line. You can then seal this barrier with a waterproofing agent. I've created a rendering below to illustrate.

Between resealing the joint and adding that small edging, you’ll create both a waterproof seal and a physical diversion, which together should go a long way to keeping water away from the slab.

Let’s see if @Nailbag has any thoughts on this.

Please let me know if you have any questions.

Mitchell