Repair gap between external wall and concrete slab

DIYNotIan · 18 Mar 2024

Hi

There are some areas around my house where there's a gap between the concrete slab/path and wall. In at least one place the water is getting in enough to make the wall wet inside the house.

What's the best stuff to use to fill the gaps?

Should I look to fill the gap with on product, and then put in an angle section of concrete to add a second layer of protection and to direct water away?

If I should be using concrete or mortar for the repairs, what mix should I use?

Or am I barking up the wrong tree completely?

Any advice much appreciated.

Cheers

Notch7 · 18 Mar 2024

are the house walls cavity construction or solid?

have you looked to see where your Damp Proof Course is in relation to the path?

If there is the correct damp proof detailing water should not be reaching inside

unfortunately filling the gap wont stop water penetration

DIYNotIan · 18 Mar 2024

Thanks for the quick response. The walls are cavity. I'm not sure about the DPC but will take a look when I get home. That being said, from memory I don't think it is visible and - if there is one - it is behind render.

The problem is quite a recent one and coincides with damage to the previous repair on that gap, which makes me think the previous repair was doing it's job until failure...

Notch7 · 18 Mar 2024

DIYNotIan said:
Thanks for the quick response. The walls are cavity. I'm not sure about the DPC but will take a look when I get home. That being said, from memory I don't think it is visible and - if there is one - it is behind render.

The problem is quite a recent one and coincides with damage to the previous repair on that gap, which makes me think the previous repair was doing it's job until failure...

Im guessing the house has solid floors?

with a cavity construction, any damp ingress no the external brickwork should not appear internally even if the damp is above the DPC

I suppose if a lot of water is getting in then maybe the cavity is filling up rather than dispersing and making the inside damp -are the inside damp patches right down by the skirting?

do you have cavity wall insulation?

DIYNotIan · 18 Mar 2024

I've found a couple of pics which may help. I'm presuming the long "crack" parallel to/beneath the pipe and extending beyond it is the DPC? What do you think?

Yes, solid floors.

Although cavity, I'd hazard a guess that the cavity could well be filled with a fair bit of crap at the bottom, which might form a bridge. If that were the case, would the moisture travel across to the inner leaf?

There are no skirtings inside. But yes, the inside wall is wettest at the bottom. It roughly forms the shape of a pyramid/triangle.

I'm pretty sure there's no cavity wall insulation.

Here's those pics. Thanks so much for the help.

DIYNotIan · 23 Mar 2024

Hi. Just wondered if anyone has any further thoughts?

I've measured up and the ground level outside is 230mm lower than inside (including the two layers of tiles on the inside, without those it's more like 170-180mm difference).

The DPC (if it is in fact the DPC) is 160mm above ground level.

Cheers

DIYNotIan · 30 Mar 2024

Good weather and a BH weekend, so hoping to get something done with this this weekend...

If nothing else, I was thinking to remove the existing knackered fillet, repair obvious cracks and defects in the ground-wall join with a concrete repair mastic, followed by a new fillet. I figured and hoped that if this worked in the past hopefully it will again.

I've no idea what mix of cement to use, whether to use SBR, etc. - so any thoughts on that would be great.

And with the additional info and measurements I added last week, any other thoughts most welcomed too.

Many thanks

diynot

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Repair gap between external wall and concrete slab

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