Garage/workshop floor slab repair

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MikeJhn

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Or think about composite battens decking boards, wont rot, but could get smelly if the edge is not sealed.
 
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Hi
Dont know if this will help, but I used a product called StormDry On the walls of my brick built garage/workshop. It stops water penetrating through the single skin walls but allows the bricks to breath. Thus keeping the inside dry. This might help water proof your concrete walls. I also dug a trench around the base which stopped water seeping in over the slab. I levelled the floor with cheap self levelling compound. I have not painted it and two years on is wearing well.
 

Bingy man

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A lot of good ideas above but to add my thoughts is cost . building products timber etc are through the roof atm and fluctuate- no 1 concern is damp will always penetrate through concrete and no 2 a 10 or 15 mm screed will not survive the temperature variations-eg frost and damp will force it to crack eventually. My fix would be a thin layer of polystyrene insulation and a good quality polythene sheet over the top of it . Use concrete at 50 to 75 mm thickness and off you go . You could put a Batton each side of your workshop/ garage and level them out -a slight fall towards the door will help with any water penetrating from elsewhere ( walls/ roof etc ) then with a suitable straight edge barrow in the concrete and tamp down until done - all in one piece. Allow the concrete to set ( slower the better) and then simply seal new floor with a suitable paint or sealer. A lot of concrete suppliers will give you a quote if you tell them the dimensions and your chosen depth. You then basically pay for what you use with no waste and they do the narrowing for u , well that’s how it works in the Midlands. You can then address the outside of your garage later -as others have said drains , sealing side etc at a later date .
 

Jonm

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I suspect that the slab extends out beyond the walls. Water runs down the wall, hits the slab and goes under the wall. Raising the inside should stop/ reduce this. Hence my comment above about gutters.
 

profchris

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The issue is, the ground surfaces surrounding the garage are all uneven all way around the garage. So water is seeping in through 3 of the 4 garage sides (one side is lower and grassed). Where the garage is situated, that sort of method wouldn’t work.

Ideally I need to raise the internal floor space some how.

Lots of suggestions about the floor, but I think you ought to reconsider drainage (as some have already suggested).

If the water isn't seeping in through the lower side, that suggests that the ground water is above the slab on the other three. If so, it will inevitably seep in.

I'd dig a hole on the uphill side to see if it fills with water. If so, a fairly shallow trench (to below the top of the slab) on the high sides, with some way to let the water flow away on the low side, should be enough to stop the water flowing in. You might still suffer from damp rising through the slab, but that's a different fix (beyond my abilities).

Drainage is a quick and cheap thing to try, assuming you own a spade :) A couple of hours work will tell you whether the water is coming in that way or, as others have suggested, coming from run-off down the walls. Eliminating ground water as a cause would be a good first step, and might even fix it!

If it works you can use pipes buried in gravel and then backfill the trench, or just leave the new ditch and clear it out once a year.
 

mg123

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I had a similar issue in my garage, it's roughly the same size as yours (approx 8 metre X 4 metre), it's a concrete block built garage that had a really rough/uneven floor and water ingress from the outside floor level at the walls as well as up through various spots in the floor. I looked through various fixes, my main aim was to get a level the floor and to prevent the water ingress.

To fix it, I laid a couple of tons of sharp sand to get the floor roughly level, added 25mm polystyrene insulation around the perimeter of the wall (approx 80mm in height) and then put down a decent gauge DPC lapped up over the polystyrene and tightly into the corners.

The next step wasn't cheap, but I then paid for a liquid pumped anhydrite screed (cemfloor). I used a company called clockwork screed from Manchester. I was overly cautious and opted for an average 80mm thickness to ensure I remained above the minimum 35mm thickness that can be laid with a liquid screed. I'm sure a more competent persons can be more confident with their levels and make use of less screed to cover the floor.

The benefits of the liquid screed are:
Speed to lay - once set up, less than 30 minutes
Setting time - foot traffic in 24/48 hours
Thickness required - 35mm
Flatness/ floor level achieved - 5mm variation over 2 metres (although I can't see anything more than just over 2mm across the entire length!)
Less prone to shrinkage so you don't need expansion joints.
And if you're so inclined, it's a better option for underfloor heating as it has better thermal properties and because of a reduced depth, is more effective.
 

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