Waterproofing awful 90s garage

[andderson365]

My garage is a great size but terribly built - it leaks at ground level and the roof needs replacing.

Figured to work on the ground level until the weather improves for the roofing.

Water is coming in at ground level where the wall meets the slab. The outside soil level was built up around the slab so I have cleared what I can to put a mortar fillet along the rear wall to which I have access. On the right hand wall the neighbours have a fence for no obvious reason, maybe they don't like brick. This was renewed as we moved in last year so it wont be getting taken down any time soon.

Does anyone have any advice for how I should deal with the wall where I cannot clear the soil (about 2") that is built up around the base? looks like a former owner tried to tank the inside but this is now flaking off (pictures below) would this be a suitable solution if I were to remove and re-tank the walls/floor in there?

Thanks for any advice on this to get me started.

 

[Ivor Windybottom]

Tanking won't achieve anything, ever. It's intended for showers, under tiles, to prevent water from the room going into the wall. It can't keep water in, your wall demonstrates what happens, it just blows off.

Is the floor below the DPC? If so then you're never going to win. But definitely dig out as much as possible. IMO you've done all the digging needed. Eventually fill with gravel, but for now leave it open and see what happens when it rains heavily.

Check downpipes - both above ground and below. 30 year old soakaways may be blocked and backing up, in which case the water just gets injected into the soil and will find its way into anything.

 

[andderson365]

Thanks Ivor, you confirmed what I was worried about.

I'm not too convinced the garage was built properly at all. The roofing that is yet to be looked at has joists the are not attached to the brickwork or each other so I have no idea how it has stayed on for 30ish years.

What do you think about laying an internal membrane down onto which I pour fresh concrete effectively raising the floor height by 1-2". Would this help to stop water seeping through the slab/wall joint?

 

[Ivor Windybottom]

I don't know, I think you'd need more than a couple of inches for it not to crack though. Especially if you're going to actually use it as a garage.

If it adjoins the house then I believe it's required to be lower, so that petrol spills wouldn't run through. Not sure if this is only if there's an internal door or not though.