Cutting a drainage groove in concrete

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  #1  
Old 09-12-09, 07:30 PM
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Cutting a drainage groove in concrete

Hi all,

Disclaimer: I'm a complete newbie as far as concrete goes; never worked with it. Please feel free to suggest alternative approaches I may not have considered!

My problem: My garage has a concrete floor (which I guess is part of the foundation). It's an old house (1906) in San Francisco and is close to the bedrock. The concrete may have been added after 1906, I don't know for sure. The garage often floods after it rains, or when people up the hill water their lawns. The annoying thing is that the water forms a big puddle on the far side (away from the garage door) then messily drains across about half the garage floor, before seeping out onto the sidewalk under one corner of the garage door.

My proposed soution: I'd like to cut a small drainage groove leading from the back of the garage (where the water enters through the raised concrete that the studs are attached to), along the wall to the garage door.

My hope is that this groove would guide the water along the wall rather than have it spread across the floor. Note that there's never a lot of water - it's only ever about 1/4" deep. The main problem is that it spreads across the floor.

Does my idea sound reasonable?

If so, how would I go about cutting the groove? A friend suggested getting a diamond blade for my angle grinder, but that seems like a very imprecise approach. Ideally, a router bit that could cut through concrete would be perfect - a semicircular shaped one. I saw some online for granite finishing - would they work for concrete too?

If my idea sounds stupid, please let me know, and any alternative suggestions are appreciated.

Thanks,

Antun
 
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  #2  
Old 09-12-09, 09:24 PM
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I would look at renting a concrete saw. On second thought, I would consider attacking the problem from the outside with drainage tile to catch the water and direct it away from the garage.
 
  #3  
Old 09-13-09, 08:27 PM
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Hi goldstar,

Thansk for your reply. Are you talking about one of those concrete saws that you push along? How would I use that to cut a groove shape?

Attacking the problem from the outside isn't really an option for me unfortunately. It's hard to explain the layout, but I'll try: My house sits on a slope. There's a 2' high poured-concrete foundation wall along one edge of the garage, so the garage is 2' lower than my kitchen. The water seeps through the other side of this foundation wall, and this area is not accessible.

By the way, that area that's not accessible (which is under my kitchen) does have a small vented outlet to allow water to seep onto the sidewalk.

Thanks and take care,

Antun
 
  #4  
Old 09-17-09, 10:28 PM
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The concrete saw will work much better than the router, besides the good diamond router bits are extremely expensive and require a special router. The ideal solution would be to saw a 2-3" wide channel parallel to the intrusion point, with a sump pit at one end. Install a small sump pump and your good to go. To create the channel you would have to cut 2 parallel lines 2-3 inches apart and then chip out the concrete between. The other thing you could do is rent a walk behind concrete grinder. Generally you can get them about 8" wide at most equipment rental places. grind a path about 1" deep and pitch it deeper at one end. Again put in a sump pit at that end.
 
  #5  
Old 09-17-09, 10:50 PM
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Hi rtagz,

Thanks for the explanation. I will probably pass on the sump pump for now, and stick to a simple groove. (There's a bunch of reasons - there isn't a sink in my garage, so I'm not sure where I'd let the water out, other than into the groove itself, and my understanding is that the bedrock under my house is fairly shallow).

-Antun
 
  #6  
Old 09-17-09, 11:21 PM
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There are some small pumps out there that you can hook a 1/2" poly hose to and run the hose out the garage door or drill a small hole in a wall somewhere.


one other option is to cut a groove with a diamond saw (and your friend was right, a diamond blade on a grinder works well) or you can get a dry cut diamond blade that will fit on a circular saw. cut the groove as close to the wall as you can, about 1" deep, and angle it slightly further away from the wall at the end you want the water to flow. this will make a 1/8" groove. Fill the groove with a good quality concrete caulk and slide a piece of vinyl flashing into the groove. This will divert the water to one side and out of the middle of the floor.

Good luck, water issues stink, I am dealing with one myself.
 

Last edited by RTagz; 09-17-09 at 11:24 PM. Reason: addition
  #7  
Old 09-23-09, 04:11 PM
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Hi all,

I've seen a lot of ads online for concrete sealers that supposedly can be applied from the inside. Since the water comes in through my foundation wall (and the whole foundation wall is exposed) I'm wondering if it may be safer to try sealing the concrete before I start cutting grooves.

Has anyone had any experience with any of these sealant products? (e.g. DryLoc, Kryton, etc.).

It sounds almost too easy - anyone used any of these?

-Antun
 
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