How to stop leaks in concrete walls?

Hi guys,

sorry to bother you guys again, I feel like maintaining a house built in the 1970s is a never-ending task😓.

There was a massive rain in my town yesterday and there's a little bit of water leak through the concrete wall in the basement. I found a crack with the drain 2 weeks ago and had a plumber seal it with epoxy resin. Fortunately, there's no water flowing through the area that he fixed. I then removed a few decking boards and try to find any visible cracks in that area, but didn't find any:(

Would I be able to seal the concrete wall in the basement with epoxy resin or do I need to install some waterproofing in the basement?

If I'm hiring a professional to repair it, do I talk to a plumber or someone else?What's your recommendation on this?

repair leaks with concrete wall

https://www.youtube.com/watch?v=dFK9Z4pOkhE&t=108s&ab_channel=QUIKRETE

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Comments

woodenwookie

My dad had issues like this because the idiot builders never sealed the bricks. In the end he used a combination of products starting with this one:

https://www.bunnings.co.nz/cemix-1l-brick-block-sealer_p0152581

Then this one:

https://www.bunnings.co.nz/cemix-2kg-aquastop_p0707041

And finished with this one:

https://www.bunnings.co.nz/cemix-4l-blue-rubberguard-waterproofer_p0245235

It appears to have fixed all his problems. The last one is the most effective.

MitchellMc

Hi @mike1360,

It's great to see that @woodenwookie has been assisting.

What is the function of the basement? Is it simply the area under the house or a room? All this blockwork appears below the house, and due to it being below the dampcourse line in your bricks, water will freely flow through it. Unless the basement was designed to be a room, I suspect no effort would have gone into waterproofing a block wall that was intended to have soil against it. Being the foundation of the house, it's OK for water to permeate through it. The solid dampcourse layer in your bricks stops this moisture from wicking up through your brick walls and into timberwork.

Waterproofing is ideally installed on the exterior side of the wall. This could include a brushable membrane and the installation of drainage to carry excess water away. Since the exterior of the wall has soil against it, you'll need to apply a waterproofer that can withstand negative hydrostatic pressure on the inside. I'd suggest Dunlop 4L Damp-Proof Waterproofing for this.

I can assist further if you can tell me a little more about the basement and why you need to stop water from entering there.

Please let me know if you have any questions.

Mitchell

mike1360

https://www.workshop.bunnings.com.au/discussion/comment/23785#Comment_23785

sorry, it's simply the area under the house. it's quite a tight space and no one lives in there. We run all the pipes down there:) I've been living in this house for 10 years, and I haven't seen the bricks get wet like this before. I assume this happened due to the house's age and changes in the foundation. It's not affecting any timberwork at the moment, I just thought it would make the house damp if there's water leaking into the wall.

Should I leave it as it is, or should I get it fixed with some sort of waterproofing products?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/74532#Comment_74532

Hi @mike1360,

You could certainly paint the inside of the wall with Dunlop 4L Damp-Proof Waterproofing. However, that will not stop moisture from being absorbed by the wall but will stop it from transferring through to under the house. Sealing the water within the wall might cause more harm than good and prevent the wall from drying out. I'd recommend sealing the wall if this were a habitable room under the house. Given there is no room under the house, I would consider not sealing the wall unless you see issues arising from dampness.

As mentioned, a dampcourse layer will be installed in your brickwork so water can not be drawn up through your mortar. It is generally acceptable that the lower section of your foundation becomes wet in heavy rain as the water is isolated to that section.

Mitchell

mike1360

https://www.workshop.bunnings.com.au/discussion/comment/100858#Comment_100858

Hi Mitchell,

Thank you so much for your advice🙏

mike1360

https://www.workshop.bunnings.com.au/discussion/comment/100858#Comment_100858

Screen Shot 2022-11-21 at 1.41.52 PM.png Do you have some sort of tutorials on how to install dampcourse layer?

Should I just lay it beside the wall and put a few bricks on top of it to make it fixated?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/117332#Comment_117332

Your walls should already have a dampcourse layer in them @mike1360. The dampcourse layer is installed whilst the brick wall is being constructed, and it's a standard building practice required on all homes.

You might not be able to see it, but unless you've noticed moisture damage on your internal walls, I suspect a dampcourse layer is present.

Mitchell

mike1360

https://www.workshop.bunnings.com.au/discussion/comment/126844#Comment_126844

If I found a drain 2-3 mitres away from the affected concrete wall, how can I create a drainage solution to divert the flow of water away from the house? then lay polythene on the ground under the house to stop any water from travelling towards the concrete block IMG_7375 copy.jpg

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/133182#Comment_133182

Hi @mike1360,

I'd suggest digging a trench 100mm wide a 450cm deep directly in front of the Besser block foundation that slopes toward the drain. You can then lay a slotted Ag-pipe in the trench and backfill it with drainage gravel. The Ag-pipe can be connected to a stormwater pipe and diverted to your drain. Any water travelling on the ground or under the surface will drop into the trench and be carried away by the pipe. Please note that you might need a qualified drainage professional to make the connection.

Please let me know if you have any questions.

Mitchell

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