Install floor drain in existing concrete

[roniish]

Hello,

here's an interesting one... I'm from Sweden and built my dream heated/cooled two-car-garage two years ago. I contracted out the whole build in hopes of getting everything done correctly, however in hindsight that wasn't a very good idea.

The garage itself is perfect when it comes to looks, electricals, network etc. BUT as you may know, Sweden gets quite a lot of snow all the way from november up until around april. My garage floor is flat with no floor drains. The snow melting off from both cars is causing a huge mess in the garage, and I have to squeegee out all the water every single day. A very tedious process to say the least.

I believe I have a few different options here:
- Rent a concrete floor grinder and grind down a slope for each of the two parking spots to slope to the middle of the spot and then core a whole through the floor and put in a drain straight into the ground (the drainage and ground work below is well made).
- Drill a couple of holes through the slab in different spots where the water may pool and install PVC-pipe to drain the water straight down
- Install some kind of trench drain either with or without a catch basin (still the issue with there being no slope what so ever)
- Use a shop vac (tedious process)
- Use a floor mat (still need to squeegee as well as having a lot of water collect inside the garage)

Repouring is definitely not an option. I'm leaning towards the first one which is to rent a grinder and try to grind down a slope and then just let the water straight through the slab into the ground. The grinding part is probably going to be hell though...

What's your thoughts on this?

 

[DGersic]

Is the slab attached to the surrounding walls? If not, maybe mud jack the back of it so there’s a 1* to 2* slope toward the door to encourage drainage.

 

[FlaGman]

What solution have your neighbors come up with? It seems like if we’re a common issue it would have been brought up during the planning process if not by you then by the builder.

 

[ConCretin]

Welcome to the GJ! Floor drains need to be considered early in the design process. The base needs to be installed to reflect the same slope as the slab to maintain a consistent concrete thickness. Honestly, I'm not sure you have any good options at this point but trying to grind the minimum pitch of 1/8" per foot into a slab and adding a floor drain would be near impossible.

Not trying to be flippant here but maybe a squeegee might be your best bet. Blaming your contractor won't fix anything. Getting "everything done correctly" is pretty subjective

 

[Mytoolsupply]

What do you currently use for heat in the garage?

It's pretty impressive how quick cars and the floor will dry with a infrared heater overhead

 

[wssix99]

If you have a big water problem and cannot reconstruct the slab, maybe grooves would help? (These are cut on airport runways to remove pooling water.)



I think this would technically solve your problem, but it would introduce other issues. Unless you have very high quality concrete, the grooves will likely chip and loose their shape over time.

 

[Dig Doug]

get a flooring fan and it will evaporate the water along with the heat
plug it into the wall w/ a timer 2-3 hours it should be gone

 

[Zeke]

Bigger squeegee.

If it is flat you could run a series of parallel cuts towards a drain point like the door? Set the saw shallow and let it down as you go. Starting at at 250 mm and dropping to a couple of centimeters in 16 feet ought to get rid of quite a bit of standing water. I'd make these wider than the width of just a saw kerf. Not sure where you'd find that blade.

@wssix99 beat me to the idea.

 

[The Cobbler]

Not sure where you'd find that blade.

double up 2 blades

 

[Dig Doug]

No cheap fix. To add a drain line

you will have to saw cut for a more permanent solution

you could add a drain box or a catch basin to catch the water then pump it out

cut in a track drain under the car to catch water then need to have flow out somewhere or use a pump

both need to saw cut

Pump w/ a float on /off switch

 

[larry4406]

Cap the slab and add pitch?

 

[Youngandfree]

Industrial dehumidifier

 

[benjy]

Pics of the garage layout would be helpful to generate ideas.

 

[Fixr]

Bigger squeegee.

If it is flat you could run a series of parallel cuts towards a drain point like the door? Set the saw shallow and let it down as you go. Starting at at 250 mm and dropping to a couple of centimeters in 16 feet ought to get rid of quite a bit of standing water. I'd make these wider than the width of just a saw kerf. Not sure where you'd find that blade.

@wssix99 beat me to the idea.

250mm? That's nearly 10 inches. Did you maybe miss a decimal?

 

[Chaznsc]

Put down some aluminum grating in the walkways? I def wouldn’t drill a hole in the slab and put that in the subsoil.

Is there any spot that seems to hold the most water?

 

[Mikes61]

How about the Racedeck that has the slots in the tiles? The water would drain below the plastic tiles, then a heater would evaporate the moisture.

 

[rayra]

Seconding Zeke. Radial sawcuts towards either a front corner or central front spot at the door, where a slot drain can be cut in where the driveway meets the garage slab or door, and from there sloped to drain away properly.
Start the saw cuts at the far reaches and steadily increase the cut depth as you traverse to the collection spot / sump. But your deepest part of the cut doesn't need to be deeper than 3/4" to get the job done.

But first you say 'flat'. you need to really determine if and where it is so.
Cannot imagine why a garage slab would be flat, especially somewhere that it snows so much.

 

[Hobby_Man22]

Put down some aluminum grating in the walkways? I def wouldn’t drill a hole in the slab and put that in the subsoil.

Is there any spot that seems to hold the most water?

The slab is supposed to be sloped towards the drain kind of like a sink.

 

[Sturgeon]

Wesis idea's pretty novel, same issue in my garage for a few months out of the year. Not so bad it can't be dealt with but the down spout drain outside of garage wasn't provided with a drain. So now I end up with a skating rink across the hard surfaces going into garage and towards entry of house. Err, so come spring / summer I'm cutting blacktop, wide enough for bucket on backhoe and digging down four feet. Filling with drain pipe and drain rock. Wesis idea is a pretty good one I think, just have to cut enough to cover areas where tires are running on. In my case twenty-four inches wide + - would catch all the snow falling off vehicles .

 

[i4ni]

Long Trench drain with sump pit or through wall drain pipe

 

[thammel]

The floor catch mat works pretty darn well. If a lot of water has collected you could always use a shop vac to get it out. I bought one of those mats a few years back from Amazon. When I used it, it was very effective.

 

[roniish]

Thanks a lot for your replies guys. I have attached some images of the floor as well as the ground work. I have put a level on the floor and it's pretty much dead flat.

I have an air heat pump in the garage, keeping about 15C (59F) in the winter time as well as a dehumidifier. These two together evaporate a small amount of water on the conrete pad without issues, but the pooling water after driving in a snowy car (I of course remove as much snow as a possibly can before driving it inside but it's a ****** process) would take weeks to evaporate.

What about cutting up the concrete in each of the two spots where the cars sit, dig into the garage from the outside (it's all regular soil, no asphalt or anything like that) and add two drains (one for each spot) and then repouring the concrete with a slope under each car? I guess this would be quite an expensive process to cut up and remove all the concrete and then repouring - but at least it wouldn't be the WHOLE slab, just a part of it. And then whe the cars have snow on them, it all just melts downwards onto the repoured part of the slab below into the drains in the center of each spot?

 

[alwaysFlOoReD]

Add concrete on top to form a slope. I've seen it done (after the fact) in a quonset. But you will lose some headroom.

 

[roniish]

Add concrete on top to form a slope. I've seen it done (after the fact) in a quonset. But you will lose some headroom.

I thought about that too but not sure that would work too well... and it would probably look like **** too. It would create a higher ridge driving into the garage as well as creating a ridge at the other end that may end up being a tripping hazard (if not doing the whole garage, but that would mean tear out the whole workshop I have behind me that isn't visible in the pictures). The headroom is quite low as well as you can see (I was not allowed by the municipality to build it any higher). I can't even open the boot on my car without it hitting the roof.

 

[75gmck25]

Where are you located in Sweden?

Most of my father's family came from the Skovde area in Sweden in the early 1900's, and I've been planning to make a trip there in the next couple of years. My son already visited Sweden, but he was there primarily for hiking, which was not in the Skovde region.

 

[roniish]

Where are you located in Sweden?

Most of my father's family came from the Skovde area in Sweden in the early 1900's, and I've been planning to make a trip there in the next couple of years. My son already visited Sweden, but he was there primarily for hiking, which was not in the Skovde region.

Stockholm, boringly enough... We don't get too much snow here compared to the north, but more than the south.

Any takes on the latest suggestion of cutting up the concrete?

 

[WildBill]

I used to use a car sized mat with a lip around three sides to direct water to the door, worked good. Worst case with a lot of snow I cracked the door and pushed the water and snow out with a shop broom.

 

[dougf]

I think adding a drain at this point wouldn't meet your intent. You would still have to manually move the water to the drain without proper grade to move the water. Have you considered one of the many brands of large mats designed to park on that have open drain channels that directs the water towards the door? Getting the water out is another issue I suppose, but just a thought.

 

[TurnipTruck]

Another vote for a parking pad:

Due to a faulty theodolite, I unknowingly set the forms for my prior shop with a 3/8” (in 24’) slope to the back instead of the 3/16” to the front I wanted (close to level so I wouldn’t have to shim the 2 post).
The back half would puddle due to daily snowmelt and was soaking the walls. I bought one of the parking pads with a built-in 3/4” dike and kept a dedicated 2 gallon wet vac in the corner every winter, filling it at least once every morning. I used strips of carpeting to protect the pad from the studded tires.
The adjacent bay had an 8” diameter pipe a foot deep centered under her car with a slight slope, draining into the gravel. That bay was never wet the next morning.

 

[Sturgeon]

What a dilemma, after reading thru all the post, for me it would be door #1, cut slots in concrete to direct snow melt or #2, rubber mat to trip on for people with bad backs. Tough spot my friend.

 

[roniish]

What a dilemma, after reading thru all the post, for me it would be door #1, cut slots in concrete to direct snow melt or #2, rubber mat to trip on for people with bad backs. Tough spot my friend.

Def. a dilemma... Thats why I thought about just permanently fixing it by cutting up the two spots, add drains and repouring the spots with a slope down towards the middle. Then I wouldn't have to ever worry about snow melting again. At least it sounds logical in my head...

 

[Sturgeon]

Though about the floor drain idea, great for new floors. After the fact not so much. Best of luck.

 

[roniish]

Though about the floor drain idea, great for new floors. After the fact not so much. Best of luck.

Why not? I mean - how would it not work by cutting up and repouring just the car spots?

 

[Sturgeon]

In my case when I leave my place I'm on blacktop. At the beginning of are private road you have to turn left or right and drive on 50% rock / 50% dirt. And it stays with you all the way back home. Clean truck one second, dirt covered the other, that fast. So answer is floor drain would have to be made so the drain pipe extends up into drain (near to top but under the grate) through to try to stop solids from entering drain pipe, a constant maintenance issue that couldn't be over looked. Also for you where is drain going to terminate, A dry well then a little drain field, or better yet daylight the end. But in your climate I suspect it would freeze.

 

[PhantomEB]

I put in a small 2” drain in the middle of mine just to keep the snow melt running over to the project side. It’s worked but I also know I need to shop vac it out once In a while. kept me happy enough I plan to add in 3 more around the daily driver side.

 

[kyrbz]

Maybe something like this. I notice one of the revues is a person in Colorado that has lots of snow and they say it catches and holds all the melting snow off their car, but they have to occasionally vacuum sand and dirt off of it. I have some of these in my garage mainly for catching oil from my vintage cars and motorcycles.

VEVOR Garage Floor Mat, 8'10"x22' Waterproof Protection from Water,Snow, Rain,Mud and Oil for Cars, Non-slip Heavy Duty Containment Mat with TPE Anti-Leak Backing & Easy to Clean & Cuttable | VEVOR US

Discover VEVOR Garage Floor Mat, 8'10"x22' Waterproof Protection from Water,Snow, Rain,Mud and Oil for Cars, Non-slip Heavy Duty Containment Mat with TPE Anti-Leak Backing & Easy to Clean & Cuttable, Professional Floor Protection and High Absorption Leak Protection at lowest price, 2days...

www.vevor.com

 

[Hakeem]

Why not? I mean - how would it not work by cutting up and repouring just the car spots?

It’s a fair amount of work but plumbers in the US do it all the time to install new plumbing. You need a saw that’s large enough to cut through the slab, assuming it’s 4-5” thick a standard concrete saw can do it. Cut through the slab, remove the old concrete and whatever’s underneath, lay your plumbing, cover with gravel, pour concrete, done.

Working at average DIYer pace I’d figure one day to cut the slab, one day to dig out, one day to lay plumbing and pour concrete.

 

[Hakeem]

Welcome to the GJ! Floor drains need to be considered early in the design process. The base needs to be installed to reflect the same slope as the slab to maintain a consistent concrete thickness. Honestly, I'm not sure you have any good options at this point but trying to grind the minimum pitch of 1/8" per foot into a slab and adding a floor drain would be near impossible.

Not trying to be flippant here but maybe a squeegee might be your best bet. Blaming your contractor won't fix anything. Getting "everything done correctly" is pretty subjective

A garage slab that was poured flat was not done correctly, the customer shouldn’t have to request that their garage be built with proper drainage

I’m not a big fan of blaming the contractor but I’d like to hear why the garage was poured flat. Assuming that it is, in fact, flat, and not at the standard 1-2% pitch

 

[Sturgeon]

Did I mention vent for p-trap or you could over size wast pipe and tun it into indirect venting along as you stay with in distance.

 

[Jones]

Not sure what your exterior drive looks like but if you installed a trench drain parallel with the garage door entry - you can get drains that are presloped inside to make the water exit to the sides while keeping grates level. Then I would cut in trench drains under each parking spot (centered) that T into those trench drains. Cut the concrete about a foot wide for drains in garage so the new concrete can be slightly sloped down to them. Not a perfect solution but it would keep your driving surface level and you could just squeegee much easier to those trenches if needed.