Slope or No Slope on New Garage Floor

[julian abram]

I built our house in 1992 with a three car garage, garage floors level. My youngest daughter just got her driving license so now I've got 4 drivers and 4 vehicles. Old dad now gets to park his truck out in the yard as daughters and wife have taken over the garage spaces. I had a concrete guy out today to discuss building on another garage space. He had a pretty strong mind set that I needed a sloped floor in the addition. I told him I did not like sloped garage floors and wanted it level. I'm outside city limits so no code to meet. Yes, for the past 28 years we get a little water puddled in the garage with level floors but it has never been a big problem. I think the slope would aggravate me more than a little standing water. The garage floor is 2 blocks down from the main house slab. I told him I would think about it, his crew is coming next week to pour the footings. What say you, slope or no slope on a garage floor?
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[John E. Hobart]

I built mine with no slope, much prefer it that way.

[Nathan Johnson]

Mom and Dad get the garage. Kids park in the driveway.

:)

[Bruce King]

Garages with main water valves or water heaters definitely need a slope regardless of code. If you want flat, that’s fine, just tell them to make a drop down depression for the bottom of the garage door to rest on a lower level, just 3/4 will do. Even sloped garages need that depression in areas that get torrential rain.

[Ronald Blue]

Flat is good. Then get a floor squeegee and you can push any puddling out the door.

[Ole Anderson]

I went the other direction when I replaced my garage floor ten years ago. I put small floor drains (3" PVC) under each parking space to catch drips as slush melts off my vehicles. Love it. But Michigan isn't Arkansas. My backyard slopes away fast from my garage (I have an 8'x18' main door in the front and a 7'x8' rear door) so I could daylight the drain pipe with a "miter grate". Shop is in the basement so level isn't an issue for tools.

[Malcolm McLeod]

Attached or detached? Attached may be worthy of considering how a oil/gasoline fire will 'flow' and so impact the balance of the house. But that aside....

If the space is to be used purely as 'average' vehicle storage/shelter, I'd probably slope it 1"/10'. If heavy rain or runoff accumulates and flows toward or past the door, I'd probably put a 1/2" to 3/4" vertical lip within 2-3" of where the door closes as a dam. You'll never have to worry about what comes off the vehicles.

If you're building race cars and shooting elevations and alignments off the floor, then pour it dead flat, with only a 1"/1' slope in the the 1st 1' entry to the garage - just to keep heavy rainfall out. Forget what comes in on the vehicle.

Is some or all of the garage space to be a shop?? If so, then I'd build it like the 'race car' shop. My last shop was poured like such. This small sloped area created a 'no go zone' for rolling big tools, but was manageable, met code, and presumably helped with re-sale. My current garage shop has 4"/25' slope and, comparatively, is like working aboard the Titanic 20 minutes before she went under. Never again. (I keep trying to rationalize leveling sleepers and ply floor. ...Maybe next week?)

[Jim Becker]

Personally, I prefer no slope, but then again, I don't use the "garage" as a "Garage". Since this is an add-on, I'd want to match existing, however...so if that's no slope, the new would be no slope.

[Jerome Stanek]

When they poured my garage they didn't put a slope in it and I wish they would have. I wanted it to slope and they told me it has slope but when I checked it didn't. National code calls for a 1/8 inch to the foot slope. I tried to get the concrete guy back but he ignored my calls so I filed a complaint on the BBB and he said he replied but there was never a reply. I wanted to take him to small claims court but as I was getting the process started I got sick and when I started feeling better the Covid hit and the courts closed down. It is dangerous as the snow melts off the car and puddles and then freezes.

[Rick Potter]

I just built a new garage, and the inspector made sure it had a slope. I wanted a flat floor, the city wanted to make sure I was not going to make it into living space.

Slope made it more difficult to level the lift and shelving I installed.

No ice to worry about here.

[julian abram]

Yes, it will be attached, a 16'x22' that will match up with the existing 3 car garage. It would be a good shop space but I have a shop in the backyard. Only planning to use this for my full size Chevy truck plus some extra storage for some construction supplies & tools, bicycles, maybe riding mower. Thanks for the good input, a lot of good suggestions.

[Paul F Franklin]

Often, at least here in NE Ohio, garages have a drain in the middle and the slab slopes toward it from all directions which means it is not level or flat. If I was doing it, I would have a flat slab that sloped either to the doors or to a linear drain. A flat slab slightly sloped wouldn't cause much trouble for shelving, storage or tools for that matter. It's when the slab isn't flat that causes the most trouble. YMMV. The drop down where the doors land is an excellent suggestion; my garage is like that and wind blown rain won't get into the garage as it stops at the lip.

[roger wiegand]

mine has a slope down to a point about where my car door opens. In good times it means I step out into an inch deep puddle of water, come january it's a small skating pond that threatens to put me on my keister when I get in or out of my car. In dry weather I don't notice the slope, the rest of the time I really wish they'd given it a uniform 1/8" per foot slope to the door.

[Gail Ludwig]

Slope or drains! Our garage has a flat floor and any moisture —from rain or snow covered cars—just puddles. You step down (4inches) from the house into the garage and you step into water if the weather is nasty. If I had the chance for a redo....I would put in drains under each car bay, as someone else suggested. Keep the edges of the garage flat for cabinets and tools...but if you are going to park cars inside, have something to get the water out.

[Ronald Blue]

Slope or drains! Our garage has a flat floor and any moisture —from rain or snow covered cars—just puddles. You step down (4inches) from the house into the garage and you step into water if the weather is nasty. If I had the chance for a redo....I would put in drains under each car bay, as someone else suggested. Keep the edges of the garage flat for cabinets and tools...but if you are going to park cars inside, have something to get the water out.

Sounds like poorly done concrete work to me. My last home and my new home are both flat pours. Very little puddling in either but I have a squeegee if I need to push the melt off out the door for some reason. Fully insulated so it doesn't freeze either. There is a slope leading up to the garage door bottom seal plus the approach is about a 4 foot rise in 60 feet. My shop has a floor drain. I've had it both ways and either works if done properly.

[Bernie Kopfer]

We have snow and slush to contend with in the winter. And the #*$-+## that put in the garage floor did such a poor job with the slope that the melt runs into the corner by the garage door. I have to use mats under the cars to hold the water. Then I can just squeegee it out the door. I bought this house preoccupied but would put drains in if I had a choice. But I took the third bay and incorporated it into the shop and sloped floors are a pain🥴

[Dave Zellers]

I'm a gentle slope guy, but without any code requirements,

He Who Payeth, Sayeth.

[John Goodin]

All my houses have had a slight slope but never has any puddle drained out an exit so the real effectiveness is in question. Most have also had a concrete ledge to elevate the framing off the floor negating any real need for a slope. All that said if I ever built a house I would want a level floor. At the moment my table out-feed table is shimmed to make it coplaner with the table saw. I am not sure if living in an area that does/does not get snow makes a difference.

[Dave Zellers]

I am not sure if living in an area that does/does not get snow makes a difference.

Yeah I was going to bring up the location thing. I would think it absolutely matters. Cars can come in with large snow packs attached behind the wheels. In our previous house I had the garage floor sloped both sides to the middle and back to front. Nothing stored around the permitter ever got wet.

It's at least something to pay attention to when the floor is poured- it would be a drag if water flowed to a storage area. Heck, having lived in snow areas my whole life, I remember seeing floor drains in many older garages growing up.

[Frank Pratt]

The concrete guys always seem to make an effort to have the drain be the highest point in the slab :confused:

[Frederick Skelly]

I'd slope it slightly. But if you keep it level (no slope), I'd consider putting a small floor drain in the middle.