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Garage Floor Wet - Rising Water

Sebo027
Posts: 212 Forumite

Hello.
I have a detached double garage that's build in the garden, and it is often flooded. Sometimes the entire floor is submerged in 10-15mm of water. I'm not sure of the exact thickness of the concrete base but there's easy 8" visible above ground.
When it rains heavy, water can be seen to pool up in other areas of the garden, including infront of the garage. If i think back, the area where the garage now stands was prone to becoming water logged for a day or so after heavy rain. The garage didn't always flood, so I am thinking the damp proof membrane has failed and the ground water is rising up through the concrete.
I have had the roof checked, no problem slates. All the garage walls are free, there is no earth resting on them and they are elevated above ground level. There's also no obvious areas where water is running in. I have actually walked into the garage when it rains and saw an area in the middle of the floor begin to get damp.
I am planning to paint the floor and lower brick work with KA Tanking Slurry. It's claimed to be able to withstand 7bar of hydrostatic pressure, and if true that should surely be able to hold the water down, or atleast divert it elsewhere. After that I am planning to cover the tanking slurry with a self leveling concrete compound, to protect the tanking and give the floor a decent finish. I have planned for a 10mm thickness.
Next summer I think I will bring in a drainage specialist to look at installing some french drains or soak aways to help improve the drainage adjacent to the garage and other areas of the garden.
Does anyone have any thoughts or experience from similar jobs they've carried out?
I have a detached double garage that's build in the garden, and it is often flooded. Sometimes the entire floor is submerged in 10-15mm of water. I'm not sure of the exact thickness of the concrete base but there's easy 8" visible above ground.
When it rains heavy, water can be seen to pool up in other areas of the garden, including infront of the garage. If i think back, the area where the garage now stands was prone to becoming water logged for a day or so after heavy rain. The garage didn't always flood, so I am thinking the damp proof membrane has failed and the ground water is rising up through the concrete.
I have had the roof checked, no problem slates. All the garage walls are free, there is no earth resting on them and they are elevated above ground level. There's also no obvious areas where water is running in. I have actually walked into the garage when it rains and saw an area in the middle of the floor begin to get damp.
I am planning to paint the floor and lower brick work with KA Tanking Slurry. It's claimed to be able to withstand 7bar of hydrostatic pressure, and if true that should surely be able to hold the water down, or atleast divert it elsewhere. After that I am planning to cover the tanking slurry with a self leveling concrete compound, to protect the tanking and give the floor a decent finish. I have planned for a 10mm thickness.
Next summer I think I will bring in a drainage specialist to look at installing some french drains or soak aways to help improve the drainage adjacent to the garage and other areas of the garden.
Does anyone have any thoughts or experience from similar jobs they've carried out?
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Comments
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Are you 100% sure about the integrity of the roof? Check again.
Otherwise it could just be on lower ground than the rest of the house but this should have been obvious from the survey.No man is worth crawling on this earth.
So much to read, so little time.0 -
Most garages do not have a damp proof membrane in the floor - Mine doesn't, neither do any of the other outbuildings.Garages are inherently damp, particularly during the winter months. That said, if you have standing water inside, then you need to look for the source - It is either coming in through the roof or under the main door. No point in wasting money on waterproof tanking slurry, as it won't fix anything until the source of the flooding is fixed. French drains & general drainage would be the starting point, so do that first.Her courage will change the world.
Treasure the moments that you have. Savour them for as long as you can for they will never come back again.0 -
Does this garage have a door?Damp proof courses are for dampness, not actual flooding. I'm a bit confused as to how using tanking slurry is going to help when garages have doors.You really need to look at it when it's raining to assess how the water is getting in, but tanking slurry sounds a bit odd.You could have a low water table, you could have slow draining ground. Where does the water from the roof end up? Where does the rainwater pipe go?You need the true cause before you can assess what the remedy is.Everything that is supposed to be in heaven is already here on earth.
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Thanks for the quick comments. The garage is detached from the house and sits further up the garden.
It has a side door and there is a also a sliding garage door. The water is not coming from either, as it starts in the middle of the concrete slab.You could have a low water table, you could have slow draining ground. Where does the water from the roof end up? Where does the rainwater pipe go?Both down pipes pour into two DIY soak-aways. Without a doubt there is slow draining ground, or the water rises to a natural level above the concrete.
I am considering installing some french drains around the garage and adjacent areas to help the water run off quicker.
As for the tanking slurry, I'm not sure what the query is? Tanking slurry provides a water proof skin that holds back damp / water. My hope is that is prevents the water rising to the surface of the concrete slab.
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Mickey666 said:Doozergirl said:Does this garage have a door?
There are occasions where the floor is submerged at the "back wall" and the area near the roller door is dry. I installed these weather defenders a few years ago and they stopped all water being "blown in" under the garage doors.0 -
Mickey666 said:That implies the floor is not level, otherwise how could it be submerged at the back and dry at the front. Damp at the back I could understand, but 'submerged'? If truly level then and water anywhere should flow to cover the floor evenly.Random thought - would it be practical to add, say, a 2-3 inch slab of concrete to the existing floor? It probably wouldn't stop the floor becoming damp but it should prevent it becoming 'submerged' with standing water as it would be able to flow out onto the lower ground outside. Perhaps some small drainage holes through the walls could help as well. Far from ideal, I know, but given the current situation . . .
I have considered that. My worry would be that, if the water is rising up, in theory adding an extra 2-3 inches would stop the problem, the water would continue to rise, until it reaches the surface and can run out horizontally. In my mind what is happening is there is water lying front, back, adjacent to the garage - beneath ground level and visible on the surface in places. The water can't run off quick enough and as a result the pressure drives it up through the concrete slab. When it reaches the surface of the slab (the floor of my garage) it forms a puddle and grows along the floor so long as the pressure keeps driving water upwards.
I am hoping the tanking will keep the water from reaching the surfaces, possibly forcing it to migrate along and out side wards. It may even result in more surface water adjacent to the garage, which is why I think the next phase to fix it will be installation of french drains and some soak aways. Would i need to run the french drains into a drain or guttering system to let the water run off?
Ref this link: https://www.permagard.co.uk/advice/tanking-a-cellar-guide
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It sounds like you have an uneven concrete slab that doesn't slope towards the main door as garage floors should. Concrete is pretty impervious to water* and will not well up unless you have some major cracks or poorly sealed expansion joints. Seal any cracks, add a layer of screed with a slope towards the main door, and much of the problem with water will disappear.*) Concrete is ever so slightly porous so will allow a tiny amount of moisture through, but not enough that you would or could measure.Her courage will change the world.
Treasure the moments that you have. Savour them for as long as you can for they will never come back again.1 -
What if there's a crack in the concrete?0
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One year on, here's an update:
I emptied the garage and tanked the entire floor, and two bricks up. I then put down a fast setting hard concrete screed ontop to protect the tanking. During lighter rain, it kept the water out. During heavier rains, the water began to pool at the front of the garage and then force it's way under the garage doors. Now because of the tanking, it couldn't drain away.
I installed a channel drain in front of the garage doors and then ran 110mm drainage pipe down the side of the garage. Last week we have a massive flash flood in the town and the garage managed to stay dry. So I hope I have fixed the problem.
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Sebo027 said:One year on, here's an update:
I emptied the garage and tanked the entire floor, and two bricks up. I then put down a fast setting hard concrete screed ontop to protect the tanking. During lighter rain, it kept the water out. During heavier rains, the water began to pool at the front of the garage and then force it's way under the garage doors. Now because of the tanking, it couldn't drain away.
I installed a channel drain in front of the garage doors and then ran 110m drainage pipe down the side of the garage. Last week we have a massive flash flood in the town and the garage managed to stay dry. So I hope I have fixed the problem.
One year on, here's an update: I had my garage knocked down and rebuilt from scratch and in fact extended a kitchen and utility rooms. Cost a fortune but I am oh-so happy now we're not far off completion!No man is worth crawling on this earth.
So much to read, so little time.0
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