Installing a floor drain in an old garage

[k p]

Okay, this may be a tricky question and I fully expect to get very polarized opinions about it...

Long story short, I just bought my first house back in December of 2012. The house was built in 1948 and I'm guessing the garage was built at the same time. The garage slab was not done very well and it has some pretty bad spalling and cracking, that's besides the point.

My problem is that when I park my car in the garage in the winter, the snow melts and collects in the middle of the garage, I'm not a huge fan of this.

I was thinking of renting a coring bit and cutting a drain hole (not sure of the size yet) in the middle of the garage to take care of this water. There will be no oil or chemicals going into this drain EVER. Only water.

Question 1: Do you foresee this weakening or causing further cracking in the concrete?

Question 2: If I core down through the entire slab down to (hopefully) the stone below, do you think it can handle the water and absorb it without eventually overflowing? (Silly question but I'd like to get some opinions)

 

[Erampu]

Question 1. Yes, I think it will undermine the existing concrete.

Question 2. Seeing as you're in Canada, I think the ground will probably be frozen at the bottom of the hole, resulting in the water going into the hole freezing, too, which will fill the hole and block it from further draining.

Note: I'm in no way an expert on this kind of thing.

In any event, good luck.

 

[STINEY]

I'd bet serious money there is no stone below. They did things differently in 1948, at least in my experience.

And if there were a stone bed, you really don't want to use it for a French drain.

Maybe cutting out a 3x3' area, digging down 3-4' filling with gravel (not just stone) and cementing over with a drain?

 

[Junkman]

I did the same thing in my garage back in the late 1960's, and it took all the water without any problems. Today, if I were to do it, I would use a PVC floor drain, so it would catch any sand that might be traveling with the water. I doubt that the slab under the floor will ever freeze, and I also doubt that the amount of water will ever cause you any settling problems. Whatever material under the floor was going to settle, it has already settled as much as it is going to. The only time you might get additional settling, is if you were to flood the floor on a regular basis.
In my next garage, before the floor was poured, I put a plastic barrel in that I had drilled holes in the side and bottom. Then surrounded it with stone, and put the drain into the top, and sloped the concrete toward the drain. It never was a problem either with snow melt.

 

[mygarageone]

With the amount of water you are talking about you should not have issues with slab or footings , but you should dig the hole as deep as you can to allow for build up and then fill the hole with P- stone or rock.
It's done all the time up here in Michigan's U.P , Munising area. Our winters are very much like yours.
But if your garage is not heated the water will freeze and then it will do no good.

 

[HMCFab9]

My dad many years ago drilled a couple 1/2" holes in his garage floor right where the water would pool. He had a concrete bit with a long rod welded to it.
Works great..... the floor is fine, no problems.
I could see if you were going to wash your car in there that it would be a problem, but you're not doing that.

 

[k p]

Question 1. Yes, I think it will undermine the existing concrete.

Question 2. Seeing as you're in Canada, I think the ground will probably be frozen at the bottom of the hole, resulting in the water going into the hole freezing, too, which will fill the hole and block it from further draining.

Note: I'm in no way an expert on this kind of thing.

In any event, good luck.

Thanks for your input. I have my doubts about the ground being frozen below the slab but I'm no expert either.

I'd bet serious money there is no stone below. They did things differently in 1948, at least in my experience.

And if there were a stone bed, you really don't want to use it for a French drain.

Maybe cutting out a 3x3' area, digging down 3-4' filling with gravel (not just stone) and cementing over with a drain?

Valid suggestion. The only thing that worries me about that is now I have a 3x3' area to properly compact and repour, which with my luck would probably end up giving me a much larger problem to solve.

I did the same thing in my garage back in the late 1960's, and it took all the water without any problems. Today, if I were to do it, I would use a PVC floor drain, so it would catch any sand that might be traveling with the water. I doubt that the slab under the floor will ever freeze, and I also doubt that the amount of water will ever cause you any settling problems. Whatever material under the floor was going to settle, it has already settled as much as it is going to. The only time you might get additional settling, is if you were to flood the floor on a regular basis.
In my next garage, before the floor was poured, I put a plastic barrel in that I had drilled holes in the side and bottom. Then surrounded it with stone, and put the drain into the top, and sloped the concrete toward the drain. It never was a problem either with snow melt.

Excellent input, thanks!

With the amount of water you are talking about you should not have issues with slab or footings , but you should dig the hole as deep as you can to allow for build up and then fill the hole with P- stone or rock.
It's done all the time up here in Michigan's U.P , Munising area. Our winters are very much like yours.
But if your garage is not heated the water will freeze and then it will do no good.

This is precisely what I had in mind. I figured I could rent a small auger bit to dig out a cylinder of soil and then fill it with stone. Cheers!

My dad many years ago drilled a couple 1/2" holes in his garage floor right where the water would pool. He had a concrete bit with a long rod welded to it.
Works great..... the floor is fine, no problems.
I could see if you were going to wash your car in there that it would be a problem, but you're not doing that.

Good idea, this is by far the least intrusive method.

 

[Andrew LB]

I would take a concrete saw and cut a 1/4-inch wide groove from the center where the lowest point is to the door opening, deep enough so the water would run out the front of the garage. This would probably be a much easier route to take than punching a hole straight down. Plus I don't like the idea of draining water under the slab/foundation.

Also, I assume they salt the roads where you live, and the buildup of this salt in the drain hole would definitely not be a good thing. The pitting and flaking of the concrete you already have experienced is due to salt damage. I'd want to keep that up on the surface and not deep within the concrete like you'd get from going straight down.

 

[p_mori7]

You will not have any problems, unless the garage is at the lowest grade point in your area...then water might want to come back up in the spring during the thaw.

I've seen many many like that (uncle, grandfather, dad) all were fine.

Drill a 3" hole, drill as deep as you can into the soil, fill the hole to the bottom of concrete with 3/4" net stone, counterbore a little larger 3-1/4 or 3-1/2 and 1/4" deep, install a floor drain cover.

Done.

 

[k p]

I would take a concrete saw and cut a 1/4-inch wide groove from the center where the lowest point is to the door opening, deep enough so the water would run out the front of the garage. This would probably be a much easier route to take than punching a hole straight down. Plus I don't like the idea of draining water under the slab/foundation.

Also, I assume they salt the roads where you live, and the buildup of this salt in the drain hole would definitely not be a good thing. The pitting and flaking of the concrete you already have experienced is due to salt damage. I'd want to keep that up on the surface and not deep within the concrete like you'd get from going straight down.

Cutting a channel into the concrete wouldn't make much difference, the channel would follow the same slope of the floor. The salt is not the cause of my floor pitting/spalling, it was the quality and placement of the concrete when they poured it. My neighbours is the exact same and they were poured the same day. Keep in mind the slab is not very thick, any potential damage by salt draining past the cut concrete would be very minimal.

You will not have any problems, unless the garage is at the lowest grade point in your area...then water might want to come back up in the spring during the thaw.

I've seen many many like that (uncle, grandfather, dad) all were fine.

Drill a 3" hole, drill as deep as you can into the soil, fill the hole to the bottom of concrete with 3/4" net stone, counterbore a little larger 3-1/4 or 3-1/2 and 1/4" deep, install a floor drain cover.

Done.

Luckily for me the garage is not the lowest point, if anything it's the highest. I was thinking of doing exactly what you just suggested, rent some concrete and augering tools for an hour, easy peasy.