Water seeping through/up garage flooring

iwang · Post by **iwang** » Fri Sep 10, 2021 12:05 am

A few years ago I added an extension to my pre-fab garage. To ensure a sufficient drop/slope for rain water to run off garage roof the contractor suggested that he put the new concrete base a few inches below the existing base of the garage - place the new pre-fab wall panels on this base (a few inches below the original side panels) before filling it with concrete from the inside until it was flush with the original floor. So the interior floor is above the exterior base. But after a heavy shower of rain water seeps in and up through the floor. There's no way of getting to the base from the outside as it tapers off with my neighbors fence. I've tried silicon (lasted a few months) and I recently waterproof tar paint - but again to no avail! Any suggestions?

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Someone-Else · Post by **Someone-Else** » Fri Sep 10, 2021 12:39 am

Did he put down a DPM? It looks like the rain is coming up through the concrete.

dewaltdisney · Post by **dewaltdisney** » Fri Sep 10, 2021 6:56 am

I agree that it would indicate that no membrane was laid on the extended slab. However, I would check that the old/new roof join is not letting water in as this would be an area that could be causing issues. Lay newspaper down and see if you can pin the weeping area down to specific spots. It is will easier to tackle once you have identified the extent of the issue.

DWD

iwang · Post by **iwang** » Fri Sep 10, 2021 9:21 am

Sorry - could be that I haven't properly explained! The water doesn't come up through the floor- he did lay a membrane. The water seeps through where the side panels and floor join (where the brown paint is on the attached photo). The builder told me that it would be impossible for water to seep through at this point because water couldn't travel upwards from the outside base - but is does! I thought that thick waterproof tar paint would have done the job but to no avail. The strange thing is that there is no such problem on the other side. The old new roof join was also a problem at one time but I've fixed this now and water definitely comes through that gap between floor and sides.

wes56 · Post by **wes56** » Fri Sep 10, 2021 9:33 am

Could you post photos of the outside showing the original level and the lowered level?

dewaltdisney · Post by **dewaltdisney** » Fri Sep 10, 2021 10:38 am

I had a Marley prefabricated garage like that in my first house. As I recall it had a cement fillet around the outside edges. Have a look at Hydraulic Cement to fix a sealing joint on the inside, you may have to rake off what you have there first. It is like Postcrete and goes off really quick so you mix small batches and work methodically. Have a read-up on it and watch out for the huge variance in prices.

DWD

Dave54 · Post by **Dave54** » Fri Sep 10, 2021 11:07 am

Are there gutters on the outside?
Just a thought.

iwang · Post by **iwang** » Fri Sep 10, 2021 7:25 pm

wes56 wrote: ↑Fri Sep 10, 2021 9:33 am Could you post photos of the outside showing the original level and the lowered level?

Very hard to get in there. I've attached a photo from the inside

iwang · Post by **iwang** » Fri Sep 10, 2021 7:38 pm

dewaltdisney wrote: ↑Fri Sep 10, 2021 10:38 am I had a Marley prefabricated garage like that in my first house. As I recall it had a cement fillet around the outside edges. Have a look at Hydraulic Cement to fix a sealing joint on the inside, you may have to rake off what you have there first. It is like Postcrete and goes off really quick so you mix small batches and work methodically. Have a read-up on it and watch out for the huge variance in prices.

DWD

that sounds good. I'll probably need to use a wire brush to get rid of the paint on floor and wall as well will I? From what I've read there's one that's more of a short term solution and one that's more permanent called 'aqua stop' - Found one for £40

iwang · Post by **iwang** » Fri Sep 10, 2021 7:51 pm

Dave54 wrote: ↑Fri Sep 10, 2021 11:07 am Are there gutters on the outside?
Just a thought.

As there's a feather edge fence practically touching it that won't be possible. But I could possibly use this to my advantage by filling the tiny space between the fence and the fascia with something similar to silicone - or even attach the guttering to the feather edged fence and connecting it with the gutter that collects the water that comes off the roof. Is there a really good durable material that I could put in that little space between the feathe edged fence and my roof?

iwang · Post by **iwang** » Fri Sep 10, 2021 7:54 pm

iwang wrote: ↑Fri Sep 10, 2021 7:51 pm
Dave54 wrote: ↑Fri Sep 10, 2021 11:07 am Are there gutters on the outside?
Just a thought.
As there's a feather edge fence practically touching it that won't be possible. But I could possibly use this to my advantage by filling the tiny space between the fence and the fascia with something similar to silicone - or even attach the guttering to the feather edged fence and connecting it with the gutter that collects the water that comes off the roof. Is there a really good durable material that I could put in that little space between the feathe edged fence and my roof?