# Forum Home Renovation Concreting  Wrong slope to garage floor, how to fix?

## N0mad

The whole area under our highset house is covered in concrete that is sloping slightly towards the front of the house. This includes about 20cm that sticks out under the back garage door. When it rains it often hits the outside wall above the back garage door or the back garage door itself. It then trickles down to the slab, goes under the door and runs through the garage space to the front of the house.  
What is the easiest way to fix this? Do I get some sort of concrete grinder and fix the slope outside the door so the rain runs away from the house instead of into it? Another alternative could be to build some sort of ridge inside the door (would pool there!). What do you think.

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## autogenous

I cant find a picture. You want a plastic spoon or strip drain. Cut a strip/trench where the water is flowing in then slot the drain in across the area to catch the water then distribute it to a soak well.

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## N0mad

No picture yet, will get one ASAP. I had a closer look this morning and it is actually only 10-12cm that stick out from under the garage door. My thought was to get this narrow strip ground down a bit so it slopes away from the door instead of towards it (as seen from the outside). That way any water running down the surface of the door would run out of the house instead of into it (slab is elevated a few cm compared to the ground outside). To me it sounds like overkill to break up part of the slab to install a strip drain, even if there is a handy connection point to a greywater drain just outside. If I have to break up the slab, I might just as well break up the part that sticks out under the door and re-lay that part with the correct slope to it. 
As I see it the problem isn't taking care of the water coming in, it's stopping it from coming in in the first place. I'ts like a doctor that only treats the symptoms you're suffering from, treating your headache but not the infection that caused the headache, which is about to kill you. (Yes, I know I'm exaggerating)  :Wink 1:

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## pawnhead

Well I don't know how you're going to grind that down too easily. You should also have a small step (say 20mm) inside the door to stop wind blown rain as well. You'd also better hope there's no reo bars close to the top where it's often found. You'll probably get concrete cancer if there's less than at least 25mm concrete cover. 
I'd just hire a concrete saw and cut away the outside section, drill a few starter bars, epoxy them into the existing slab, and leave a step down when you pour the new section. 
Alternatively, you could fix the problem a lot cheaper with a tube of silicone. Just glue the door down to the slab.  :Wink:

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## AlexJ66

Hey NOmad, as pawnhead said, maybe hire a concrete saw and cut that small section off. You could then use pavers, concrete, turf or whatever you want to fill in that small section, a bit lower than the downstairs concrete slab, to stop the water coming in. Only about $120 from City Hire near you, and maybe an hours work. Would cost about the same, and take the same amount of time hiring something to grind it down with  :Smilie:  I just trimmed a slab of 8 metres long and 3 metres wide and it took me about 2.5 hours with the abovementioned saw  :Smilie:  If you posted this last week I would have stopped on my way back to City Hire (from Red Hill) and done it for you  :Smilie:  
If you block it off with some sort of ridge, as you mentioned, has it got somewhere else to run off to?

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## pawnhead

Here's another solution that may be easier, using Ardit; 
Ardit is quite expensive but it's the best product especially for thin coatings, but you could just use a strong three to one sand cement mix. There's no guarantees if you're driving trucks over it, but it should be strong enough. It would be a good idea to scabble the concrete a bit with a hammer and cold chisel to give the topping a better key.

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## N0mad

Thanks guys, both of those suggestions sound feasible and the last one is probably the easiest. Should work fine as the slab has a slight lean sideways as well. I could then easily make a small "gutter" in the slab at the side of the door where I lead the water back outside. The son of the previous owner of the house was supposedly a brickie so should have known how to do it correctly in the first place!?

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## N0mad

Looks like Ardit K15 would be the go.

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