Leaking concrete slabs

jimmers23

We have a concrete patio with a small garage underneath. We store ride on lawn mower, freezer and tumble dryer down there. However, the concrete above is cracked since it settled and it's now leaking below into the garage. We are looking for suggestions of how to stop the water coming in. Any suggestions of concrete sealer/ paint type material that would stop this. The area in question is about 40msq. Thanks

whizbang

wow. Get a structural engineer. And stay out of the garage.

However...
If the slab itself is ok, its probably pulled away from adjoining wall.

Where is the water coming in ?

jimmers23

The slabs are definitely stable, slabs of concrete were put in as the roof of the garage. Then the area was concreted again on top. Our house is on a hill so this then enabled us to build a wrap around patio with small garage underneath if that makes sense

jimmers23

The water appears to be coming in from the cracks in the concrete on the surface you can walk on.

Lumen

You essentially have a leaking flat roofed garage.

Is there a fall on the surface or is it totally level?

Is there guttering and downpipes to take rainwater away?

Tow

I have seen concrete roofs with tar on the top, insulation sheets gravel and then patio slabs

jimmers23

There is a very very slight angle for water run off and there is gutter a drain pipe. However water still accumulates. The cracks are so small you wouldn't notice them walking on top..

Cerco

Are you sure it is leaking and not condensation on the ceiling of the garage?

jimmers23

Nope it's definitely leaking

my3cents

OP google bentonite and see if you get any results that might be helpful

Essentially bentonite is used to seal leaking ponds and as an outer seal on projects that must not leak (like toxic waste). You normally mix it with fine sand and it expands to fill any gaps it get wet then remains a sort of gel. In this case I wonder if it was brushed dry into your top slab enough would go into any cracks to seal the leaks?

Even Amazon sell it https://www.amazon.co.uk/MISTRAL-Bentonex-SB-Bentonite-Engineering/dp/B01MT9KVTL/ but I'm sure the industrial grade can be got here, but don't get confused you can also get a much more expensive food grade that is used in brewing amoungst other things

Lumen

The problem here is that you have everything that's bad for a roof surface: flat, foot traffic, direct sun. And waterproof concrete is technically possible but quite hard to achieve, so was never going to work without skilled installation.

Do you any furniture on the "patio"?

This might be useful:

https://www.fixmyroof.co.uk/flat-roof-repair/

Maybe consider waterproofing and then putting a non-slip deck on it to shield it from sun and physical damage.

jimmers23

Thanks a million, looks like the stuff I'm after. You have all been a great help. Thank you