Slab sloped or flat?

[Dustin Crawford]

Hey guys gonna pull the trigger on my slab soon. I have heard arguments on each side but what is the most common; slab sloped to doors for drainage or flat?

Might sound stupid, but what I have been hearing (and it sounds right to me) is in a garage (as in primarily a parking spot) slope to drain out doors. But in a shop (as in primarily a work station) make floor flat so heavy stuff on casters and all that sort of stuff stays where you want it.

Mine will be a 'shop' not 'garage' so am I on the right track to want a flat or very slightly sloped slab?

DC

 

[darkk]

General rule of thumb, entire length of floor is sloped to the door at a rate of 1/8" per foot.

 

[Jim Stabe]

Having a sloped floor in my shop, I would strongly urge you to make it dead flat and level. Even with a sloped floor I never hose out the shop and I would like to not have to compensate for the pitch every time I want to build something on the floor or align the car.

 

[GeorgiaHybrid]

Mine is being built right now with a 3'-7" concrete stem wall above the slab and the floor dead flat. If I ever need to hose it out, the 8" thick concrete walls down low will not be hurt and I can use a squeegee to get the water out. I hate things rolling away from me and mine is a 3 car garage that is intended to be for working and seperate from the parking for the DD.

 

[mikeyr]

When we did my garage, I made one mistake, I did not specify the floor slope and the contractor assumed I would want a slope, so the 20x20 front section is sloped towards the door, I was really upset when I saw it but it was my fault for assuming he would do it flat, the second (back) half of the garage which 24x22 is absolutely flat.

I noticed my 4-post is not as steady on the sloped floor as it is on the flat floor, still safe and I am not worried about it but it seems to prefer a flat floor.

 

[ptschram]

When I was interviewing contractors, I had to tell three or four of them they had to leave my property as none of them would have any of my tomfoolery of asking for such a thing as a dead flat floor. Each and every one of them told me I'd be upset with all the puddles etc.

I told each and every one of them that I was skilled at the use of the mop and squeegee.

They were not entertained, but it didn't matter as they weren't getting the work.

I want a flat floor for more reasons than I am concerned about standing water.

 

[Falcon67]

Shop = Flat.

The old shop had water infiltration issues in a heavy rain, but it wasn't a problem to just sweep it out the door.

>I told each and every one of them that I was skilled at the use of the mop and squeegee.

What he said. My new slab has a bit of a hump that forms a depression just to the west of the hump. It'll make for an easy clean up. The old shop settled on the east side about 2" and any liquid spill on the east half made an immediate run for the wall plate and out into the alley LOL.

Nature will have the final say on anything you lay out anyway. All you can do is try to slow her down.

 

[PhantomEB]

How big of a shop? When mine gets built, oh in 10 years.. the front half by the big doors will have some slope but the workshop half will be perfectly level.

Ultimately I am gonna see if I can have it slope to middle of one bay then slope to the door so it all drains out in the middle of the bay but wont bother me if I on a creeper under the truck.

 

[Dustin Crawford]

Shop is 24' as you pull in the door and 28' long. Awesome I am glad you guys back me up on the flat floor. Thanks!

 

[pattenp]

I assume you don't have a building code requirement to slope the floor.

 

[Charles (in GA)]

Dead Flat. You will not hose it out after you get some stuff in there. A leaf blower, a broom, and a wet mop will most likely be doing the work.

Codes require slope or drains, I wanted neither, and that is what I got, my contractor understood this, as he confirmed with me.... "you want the floor sloped....." as he shook his head from side to side, and I said "yes I want the floor sloped" as I shook my head from side to side.

Charles

 

[larry_g]

I'm in the flat and level group. Just remember that your walls are flat but not level. Flat and level are two different things. Make sure that level is what you get if that is what. You would have a spec of something like no more that 1/8" variance in height in any 10 feet for flatness. If you spec a real tight flatness then be prepared to pay for it. Good luck with your build.

lg
no neat sig line

 

[rwhite692]

+1 for Flat. Especially if you ever intend on getting a lift.

 

[larry_g]

Dead Flat. You will not hose it out after you get some stuff in there. A leaf blower, a broom, and a wet mop will most likely be doing the work.

Codes require slope or drains, I wanted neither, and that is what I got, my contractor understood this, as he confirmed with me.... "you want the floor sloped....." as he shook his head from side to side, and I said "yes I want the floor sloped" as I shook my head from side to side.

Charles

Just curious if code requires a slope in a woodshop or art studio?

lg
no neat sig line

 

[v8garage]

Here is a link to a discussion on an engineering site about garage floor slope. Interesting reading. If you will notice they mention several times " garage for parking automobiles". If you are building a garage solely for the purpose of "parking automobiles" I would say slope it 1/16" per foot. If you are building a shop for working on automobiles or any fabrication work I would say make it dead level.
V/8

http://www.eng-tips.com/viewthread.cfm?qid=267972&page=3

 

[larry_g]

work I would say make it dead level.
V/8

http://www.eng-tips.com/viewthread.cfm?qid=267972&page=3

If you take a bowl and set it on the counter and then lay a level across the rim of the bowl the bowl will be level but not flat. You need both flat and level in your spec if you expect to get what you want. When the contractors cited above say you will get puddles on a level floor that may be true. The floor is level but if it puddles it is not flat.

lg
no neat sig line

 

[jimp]

My contractor poured mine level and flat (I was very impressed by how well, only a couple very small puddels when it rained) except around the 12' door. He lowered the slab 1" at the door and then sloped it over about 20', just enough for me to park. You can only notice it for the first couple feet along the sides at the door, unless it's wet.

The best of all worlds, level and flat over all except a drip area. It keeps almost all the water and ice contained for easy removal.

Sometimes your contractor will take care of you if you don't know what you are doing (I did not, he did).

 

[holdover]

mine is 40 X 60, flat, would do it the same way if there ever is a next time. Snow and rain not a problem, sweep it out. Also my 2- 4 post lifts work better in a flat area

 

[Ign]

Just curious if code requires a slope in a woodshop or art studio?

lg
no neat sig line

This has come up here before when others have insisted they want a level floor (a wise choice indeed) but their local bldg dept insists they must have a sloped floor. I suggested checking w local fab shops to see how they deal with this. Tell a welding shop they have to have a sloped floor and they'll tell you where to stick it.

The easy way out for the bldg dept is to argue residential vs commercial, I guess. But then yeah, tell them your "garage" is a personal art studio or yoga studio, and it just happens to have an overhead door.........to allow for air flow and natural light...........yeah, that's it.

 

[Kevin54]

Level or flat, no matter what, you will have puddles in the garage. Tell the contractor to make it level, not flat. Then ask him to make a depression at the garage door opening for the door so water doesn't come in. If you hose out a garage whether it has slope or not, 9 times out of 10 you have to squeegee anyways.

1/8" per foot is common for a slope, and mine is sloped that way. If I had it to do over I would have asked that it be level. For one, just for the aesthetics of it. If you have a rollaround under a cabinet, the rollaround shows up crooked. Everything is just kind of a pain in my estimation.

And as far as level vs. flat....level will be perfectly horizontal but you can have flat at a 45 degree angle.

 

[ConCretin]

A floor with 1/16" - 1/8" pitch would have to be very 'flat' to fully drain without birdbaths. It's very difficult to get a floor that flat especially on a slope.

To guarantee drainage, you'd need 1/4". Might be OK for parking but you don't want that in a work shop. Build it level except the area adjacent to the OH doors.

 

[darkk]

It's very difficult to get a floor that flat especially on a slope.

It is difficult to get a *flat* floor period, slope has nothing to do with it. To get flat even floors, a skreed machine that rides on rails is usually required.
In my town, It is code that requires 1/8" per foot slope. Drains are not allowed because of ground water regulations.

 

[bmcdowell40]

I have mine sloped to the drains which are in the center of each bay, about 1/8" per foot. Its dead level across the thresholds and slopes away from the OH doors. Really makes it nice in the winter, all the snow & ice melts off & runs to the drain. No puddles the next morning, just a dry floor.

IMHO, you're better off to build it to drain, trying to get it dead level and perfectly flat is nearly impossible without a screed.

 

[Thirsty]

I made a rookie mistake when installing my electrical outlets, I measured from my sloped floor, well all my outlets are sloped also. hehe

 

[Dustin Crawford]

A floor with 1/16" - 1/8" pitch would have to be very 'flat' to fully drain without birdbaths. It's very difficult to get a floor that flat especially on a slope.

To guarantee drainage, you'd need 1/4". Might be OK for parking but you don't want that in a work shop. Build it level except the area adjacent to the OH doors.

This is what I had thought as well. If I have it sloped enough to actually get the water out the garage (with no squeegeeing) it would be FAR too much slope for a shop.

 

[ConCretin]

It is difficult to get a *flat* floor period, slope has nothing to do with it. To get flat even floors, a skreed machine that rides on rails is usually required.
In my town, It is code that requires 1/8" per foot slope. Drains are not allowed because of ground water regulations.

It harder to get a flat floor on a slope because you don't have a consistent reference point for pads. It's not as simple as setting up a laser at a given elevation.

With all due respect, it is not true that a 'skreed' machine is necessary to get flat, even floors. We consistently get Ff 35 or better floors with hand screeding.

About the only place you see pipe rails and power screeds are bridge decks and concrete paving.

 

[Hobby_Man22]

General rule of thumb, entire length of floor is sloped to the door at a rate of 1/8" per foot.

Are you nuts? It's not a pipe it's a slab. The whole building will be angled

 

[dcg9381]

Hey guys gonna pull the trigger on my slab soon. I have heard arguments on each side but what is the most common; slab sloped to doors for drainage or flat?

Might sound stupid, but what I have been hearing (and it sounds right to me) is in a garage (as in primarily a parking spot) slope to drain out doors. But in a shop (as in primarily a work station) make floor flat so heavy stuff on casters and all that sort of stuff stays where you want it.

Mine will be a 'shop' not 'garage' so am I on the right track to want a flat or very slightly sloped slab?

DC

All of my garages are sloped. My shops are flat.
Whatever you do, put a 1-1.5" drop in where the garage doors close. That little "step" will keep water and other things out. In a garage, I slope and do the drop for the doors. Make DARN sure the concrete guys have it. I've had them miss it can have to come back and chip it all out.

The other thing to watch is make sure any walk / path / slab for shed roof is pitched away from the shop. We have one low spot, it's right outside the shop man-door. Make sure the drive slopes away.

 

[andyvh1959]

My attached two car garage is sloped and has a center drain (built in 1973), so winter slop on the cars melts and flows into the drain.

My detached 24x28 shop I built in 2019 has a dead flat floor, with two rows of 8" block around the perimeter. I just had the concrete contractor create a minor slope under the overhead door so any rainwater falling down the door drains away, same for the 36" man door.

 

[racecougar]

Are you nuts? It's not a pipe it's a slab. The whole building will be angled

That member hasn't posted here in four years, and this is a twelve year old thread.

 

[Hobby_Man22]

That member hasn't posted here in four years, and this is a twelve year old thread.

Oh im sorry let me start a new thread then

 

[racecougar]

Oh im sorry let me start a new thread then

To call out a comment from 12 years ago? Seems unnecessary.

 

[Hobby_Man22]

To call out a comment from 12 years ago? Seems unnecessary.

It has to do with the content. It's still relevant even to this day. Apparently this slope stuff has to do with a residential garage that's maybe 20ft deep. I guess this isn't done on a big workshop building type thing

 

[racecougar]

It has to do with the content. It's still relevant even to this day. Apparently this slope stuff has to do with a residential garage that's maybe 20ft deep. I guess this isn't done on a big workshop building type thing

I dunno. I'm not so sure that darkk is the one that's nuts. If he/she was, who's to say he/she still is? Heck, who knows if he/she is even still alive? Not sure how that ever was relevant, much less, to this day.

 

[ArcReactorKC]

Are you nuts? It's not a pipe it's a slab. The whole building will be angled

He was apparently nuts 12 years ago...

 

[maxpower_hd]

I think it really just depends on your use and preference. Mine is sloped to the door. I use it as a shop mostly but I do wash my floor and my motorcycle so I like the slope. I find it to be a minor inconvenience to occasionally put a shim under my welding cart. It's about the only thing that rolls so good that it might roll away. everything else pretty much stays put. But if your going to use machinist tools like lathes and so forth then you might want it dead level. I don't have a lift either so that is not a concern for me. Neither way is wrong. It's just what you want.

 

[Hobby_Man22]

I think it really just depends on your use and preference. Mine is sloped to the door. I use it as a shop mostly but I do wash my floor and my motorcycle so I like the slope. I find it to be a minor inconvenience to occasionally put a shim under my welding cart. It's about the only thing that rolls so good that it might roll away. everything else pretty much stays put. But if your going to use machinist tools like lathes and so forth then you might want it dead level. I don't have a lift either so that is not a concern for me. Neither way is wrong. It's just what you want.

I don't think mine is sloped. I watered it for a week after it was poured and the water didn't flow in any particular direction. There are a couple low spots though. I actually forgot to ask the contractor about this but it seems flat enough lol the shop sits on top of the slab so I don't see how it would work out well being slanted

 

[theoldwizard1]

Make sure your slope spec is in writing !

Friend of a friend had a new driveway installed that butted up against the house. Not sure what was spec'd but it went the wrong way ! First good rain flooded the basement (which had never flooded before despite cracks in the wall).

Not sure exactly what happened, but the new driveway was removed and re-installed with proper slope away from building.

 

[mogandave]

So is a flat wall sloped?

 

[Walkers]

Are you nuts? It's not a pipe it's a slab. The whole building will be angled

Well, whatever happened he did it over a decade ago…