Hello All. I have a concrete slab in my garage that is cleverly pitched toward the entry door to the rest of the house, instead of toward the driveway. Rain drips and snow melt from cars runs under the door and soaks the carpet. I would like to add a floor drain in that area. If I cut a hole in the slab, and another in the foundation wall (below grade) is there a way to drill, tunnel, jack or otherwise persuade a pipe into place under the slab? I know the pros can do directional drilling under a whole freeway. Is there an amateur approach that would make it ten or twelve feet? Thanks.
-Steve
Replies
Steve - Be advised that you are living with a double code-violation: (1) your garage must be a 4" step down from the house and (2) the slab must pitch to the overhead doors. The reason for this is so that gasoline leaking from a vehicle or heavier-than-air fumes do not enter the house (like the water).
That being said, it is unlikely that a single 4" floor drain will cut it here. How do you control the pitch in the vicinity of the drain? It would probably be better to use a section of trench drain (see American Drain Products for instance) - then you will be cutting a rectangular hole larger than the drain which will give you more access to subslab areas. Call some of the electricians in your area - they sometimes use a device for tunnelling under driveways that might be useful here, once you are under the slab and through the foundation wall.
T. Jeffery Clarke
Edited 6/27/2002 3:07:03 PM ET by Jeff Clarke
The house was built in 1984, and it complied with code well enough to get its C of O then. The lack of the 4 inch drop would be hard for the inspector to miss, but I'm sure he didn't verify the pitch to the overhead doors. That's just sloppy workmanship. Thanks for the idea about the electrical contractors... I'll check that out. If you saw the floor, and the way water pools right at the door, you might think a 4" drain would do it. In any event, the main question is about the tunneling. Thanks for your advice.
-Steve
IRC2000 doesn't mention the 4" anywhere I can find. If I've missed it and someone has the section number, I'd appreciate it. It does require sloping toward a drain or the main vehicle entrance.
You want a 4" drain line...
Get enough pipe to do the whole job. Dig a hole to start with, that is large enough, and dug in such a way that you will have room to work. get as far under the slab in the direction that you want to go, as you can.
Now, slide the pipe you have, in the hole, and up under the slab. Make sure it is aimed the direction you want it to go.
Now get out your garden hose. Run it up into the pipe, all the way to the other end. Turn on the water full blast. It will erode the dirt in front of the pipe. As the dirt erodes, you can push the pipe further. Then it will erode further again, etc...
Keep this up until you are in the area that you want to get to.
You can also do this by using a smaller rigid pipe, with the hose connected directly to the pipe. But you do not have as much control over where and how the erosion occurs. Nor how much erosion occurs. With the larger pipe, the large pipe itself provides the escape route for the eroded mud/dirt, past the garden hose, and you end up with a much smaller hole going through. Pretty much, you can end up with the pipe burrowed through the dirt, and the dirt still solid around it, once the water dries up from around it. (And yes, it will eventualy make it's way to the happy medium of all the surrounding dirt. LOL)
I have considered this approach. Mostly I have heard of it used to get under walkways and such for electric. I assume you have tried this. How hard is it to do? By this I mean, what kind of rate of progress do you make? Is this the kind of thing that takes hours? Also, how hard is it to maintain "aim" and end up where you want? I think there is supposed to be some gravel under the slab, but I wouldn't be surprised to find none there. I don't know if that would make it easier or harder. Anyway, this is a definite possibility. Thanks for the suggestion.
-Steve
Just remember there's gravel under that slab. Pretty tough to tunnel through - water blast won't move it much.T. Jeffery Clarke
Quidvis Recte Factum Quamvis Humile Praeclarum
As a DIY project and given the age of the slab, one has to assume that it's settled and stable so why not cut the trench in the slab with a quick cut, dig out with a shovel, install the new pipe to the outside from the new drain with the p trap bury, compact and recast the area in question.
Less risk, costs and you can do it all without outside help.
Gabe
The water boring techniques are fine for pressurized water lines and electrical conduits but not for drain and waste. You need to cut the concrete, bust it out and dig yourself a ditch. Lay the drain pipe and block it to ensure you have the correct amount of fall from the point of entry to the point of exit, (normally a 1/4 bubble on a level). Then back fill with sand half way up the side of the pipe. Add a layer of pea gravel to cover the pipe followed by the leftover dirt. Fill the ditch up to the bottom of the existing concrete. Tamp the dirt, the sand below the pipe will absorb the shock and will not change the fall, (add more dirt as necessary). Then, add your wire and pour your concrete that is mixed to code for your garage, (probably 6 sack but check the code).
If your a connecting to an existing sewer line, (hopefully not), you will also need to install a trap at the point of entry and likely need to fill it with water if it dries out during the summer. If you don't your garage will smell like sewage. It may also be illegal for you to connect to your sewer line if that is even your intention.
Yes, the cut the concrete and lay the pipe approach was always my "fall back" position. I was hoping to come up with a strategy that would allow me to get a pipe through without having to mess up the slab. Not being a mason, I'm sure I'll curse every time my mechanic's creeper gets stuck on the not so perfect edge of my repair. I figure it couldn't hurt to try something else. I can always cut the slab.
Where I live I have my own septic system, and I have no intention of hooking it in to that. The drain will go outside "to daylight". I'm not too concerned about the pitch being perfect either. Of course, we don't want it to be uphill, but we are talking about minimal amounts of water from snow and slush in the wheel wells, etc.
Thanks to all for the suggestions.
-Steve
I just thought of something. I dont have a clue if this would work for sure so your on you own if you try it. Its just a thought I had.
What if you took a concrete saw and just cut a groove from the affected area out to the garage doors. Since its not a lot of water this might be all you need to keep it from going under the door.
We have sawed control lines on our porch and the water really does follow them. It might take 1/4" or so width for the water to not bridge the gap. Wouldn't hang up the crawler wheels. I don't know if it would work in the original case, be/c only he knows how much water and what distance and what slope, but I applaud the creative thinking. Iff he was going to cut the slab to install the drainline, it'd be a harmless experiment to cut the slab as you said but in the direction the drainline would run. At the wall, he could create his drain where he had only a foot or so to reach daylight. Anyway, ultimately workable or not, I liked the simplicity and creativity.
Bernie,
Thank you for the suggestion. I agree that it might work. Would certainly be worth a try, especially if I decide to cut the slab anyway. That's why I ask you guys this stuff!
-Steve
If the amount of water is that small why not just use a hammer drill and a masonry drill (about 1/2 ") and put a hole or two staight down through the slab in the centre of where the water puddles? ( If you want to try the easiest fix first.) The water would drain away into the stone below the slab ??? -Brian.
Well, It may be a little too much water for that. Especially once a bit of sand and dirt starts to clog up the holes. Also, I live in an area where radon is an issue, so those perforations wouldn't be a good idea.
-Steve