Level floor or sloped for drainage?

[Harley Monster]

I am in the concept stage for a fairly large metal garage, 50 X 96. I have a question about the slab, should I pour it level or have a slope of say 1/4" per foot for drainage in case I want to hose it out or something like that?

If it is sloped, that is 12 1/2" in 50'...how would you plumb the building? I guess the posts could be elevated on footings.

Any one have any suggestions?

Thanks in advance.

 

[Ironcrow]

Level. To clean, you sweep and mop.

 

[boiler7904]

Level is more useful and makes framing easier.

Sloped will cause the exact problem that you're encountering unless you can pitch it to a trench drain down the center of the building. Good news is that a concrete or block stemwall 16" above the slab (3 1/2" at the high end of the slab) will give you a level surface to frame off of. 12 1/2" of pitch is excessive. You could probably get away with 6" if you have a good concrete finishing crew.

What's the building inspector going to want to see?

Whether it's level or sloped, a mop and squeegee will become your new best friends. Get a bucket with wringer like they use in schools.

 

[Crusty Nut]

Level, the most I would consider is to have the last 3 feet or so in front of the big doors slope to the outside. That way if it is raining and the doors are open it wont puddle, it will just run out.

 

[Kevin54]

The concrete guys can slope it to the center or to an opening with the opening being level. You want the outer perimeter level all the way around for building purposes. And concrete doesn't quite get slope at 1/4" per foot. I think in 28' mine is only sloped a only about 1 1/2". On a slab your size, I would have it sloped towards a trench drain somewhere convenient. Most likely in the middle. This way, any water will run away from the outer walls.

 

[kvom]

If you need to move a vehicle around on wheel dollies or heavy equipment on a pallet jack, you'll be thankful the floor is level.

 

[autoist]

Are you going to be jacking cars up onto jack stands? & rolling around on a creeper?

I say level except for the last 2' or so by the large doors....that's the way mine is done &, usually, everything ends up running out under the doors after I've pulled a car inside.

 

[blkhonda1991]

definintely sloped at one point for drainage if you re parking wet cars in there. As for framing with a sloped floor you wouldnt be framing on the slab, you'd have frost wall around the perimeter and a floating slab so it can slop as much as you want and framing will still be simple

 

[Harley Monster]

I am thanking all who have replied so far with your thoughtful comments.

I live in So. CA so I am not sure of the requirements for a "frost wall" though I think it would be a good idea just to keep moisture out.

Please keep the comments and ideas coming.

Thanks!

 

[IDASHO]

Most inspectors will want a slope.

I had one that wanted one, and wouldnt budge. So i have a sloped floor.

You cannot even tell. Seriously.

And it is nice, when the snow and ice melts off the car or truck, that it drains to thew door. Id much rather it do that than have standing water, that will eventually be ICE.

 

[rcleaver]

I plan on putting a french drain all the way down the center of the garage, parallel to the longer dimension. But I also want to be able to wash my vehicles inside in the winter and clean the floor without opening the overhead door.

 

[Deltarat]

I wanted mine level to build something it will be level without shimming it at the floor

 

[Ironcrow]

I feel strongly that I want it level. Fortunately my inspector was cooperative. If I had an uncooperative inspector I'd design my garage with the floor 4 inches lower than the real finished location, get my C of O, and then pour a level floor on top of whatever the inspector saw. F'em.

 

[ckacrum]

I have a 30' x 36' slab that is sloped with a drain in the middle. It does pose some challenges when trying to level things out on cars and certain types of equipment, but it's not that bad. If I had it to do all over again I think I would go level.
All you need is a good squeegee and mop and bucket.

 

[dps]

I'm surprised no one has suggested doing both. The floor will already be poured and screeded in sections. If there is a more-or-less permanent shop area, that could be level. Any areas with a higher amount of traffic or where you might want to wash vehicles or equipment could be sloped to a drain or a door. And a 1/8" slope would be plenty.

 

[Kevin54]

I went out and measured the drop in my floor yesterday. It has 1 1/2" drop in 28' which equals out to a little less than 1/16" per foot. It allows for drainage, but never had a problem with jackstands, dollies, etc. The floor is flat, and it is level from side to side, it just slopes the 1 1/2" from front to back.

 

[dcovey]

My shop in Texas was level..Unfortunately it still puddled water against one wall. So I had to broom it out.
The garage I'm building here in KY. I had the floor sloped (sp) towards the door. 2" in 28'. I had to put the gutter downspout on the front because the whole shop sloped that way. I didn't think of that and evidently neither did my contractor. (I'm a rookie, evidently he is too!!)

He has been building this since 22 Sept and just now maybe 1/2 done..Not to mention I now have a mechanics lein on my house because he hasn't paid for the materials...I do have a plan for him though..

Dave

 

[sonett43]

my builder told me that floor drains are no longer acceptable. Where to drain them off to? For fear of contamination with Glycol, motor oil, brake fluid, etc, the builder said he couldn't run it to the street, nor to daylight, nor to an underground seepage pit, so for the garage with teh daily drivers, we sloped the floor. My workshop, it is flat.

Lewis

 

[Ironcrow]

Yeah, that one cracks me up. There ain't nothing going down the floor drain that wouldn't be running down the driveway.

 

[5wndwcpe]

My shop is 58' feet long and the fall is 6" total, back to front. If I had to do it all over again, I'd make the back 30' level to accomodate building projects and the front 28' sloped to allow for natural drainage when I wet sand or wash vehicles. It really depends on what you plan to do in the garage. One thing I did plan for though were drains just outside of the overhead doors so anything that does get washed out of the garage doesn't **** up the driveway.

 

[Bob Paulin]

Whatever you choose, make sure to communicate it in no uncertain terms to the concrete slab guy.

Friend of mine was building a new 40' x 40' shop for his race car, and had his floor layed out perfectly level.

Told the slab guy to pour it just as it was layed out.

Came home from work only to have his idiot slab guy explain that the "idiot contractor" had not incorporated any floor pitch for drainage, but the slab guy said he took it upon himself to "....straightem it out."

My friend went from a six-inch slab to a 10-inch slab at no extra cost - thanks to the local judicial system along with paperwork signed by the slab contractor stating it was to be poured as layed out.

 

[ddawg16]

I don't think you are going to be able to get something that large perfectly flat. I think 5wnd had a good idea....back half flat and the front half with a slight slope..

I think you can have both....it can be flat...but with a slope...it just won't be perfectly level.

If you have even a 2" drop for the length of the garage, that little of a slope is not going to be an issue for projects and water will drain out...slowly, but it will drain.

My garage is 25' deep and I have about a 1/2" slope. When the foundation was first poured, I was keeping it wet for a week....and found all my low spots.....I have a couple of areas where I get about a 1/16" puddle....but for the most part it all drains out.....and that I like.....especially right now with all the rain we are getting here in S California....and I only have 1/2 my roof up....plenty of tarps but the rain is still finding a couple of ways in.

 

[tcianci]

The amount of pitch you need for water to drain is very slight, maybe an eigth of an inch to a foot of run but that requires that the floor be finished very smoothly because any dips in the floor exceeding that eight of an inch will result in a puddle. Where I live in Massachusetts, any garage attached to the house has to have a sloped floor and a minimum 6 inch curb or step where you enter the living space. This is so carbon monoxide which is heavier than air can not readily seep under the door to the living space. Also the issue with floor drains is that they are just like the bilge in a boat, flammable fumes can collect there and thats trouble.

 

[FlameOut]

I see this thread is about a month old, but found it doing my search for floor drains. I'll be pouring my 28x34 slab soon, and really didn't want a drain, but now I'm not so sure. Has anyone with a 2 bay garage made one side level and a floor drain on the other?

I was thinking of making the bay with my lift level, and other other bay with a drain in the center

 

[Harley Monster]

My first attempt at a garage in 2008 resulted in a false start for a lot of different economic reasons, I am sure you all understand.

I am once again designing a garage and have hired a contractor.

I am still interested in input on this subject; I learn a little from every post.

What slope do you have in your garage, why and are you happy? Would you do it that way again?

Sometimes things look one way on paper and turn out another after a couple years use.

Please comment.

 

[rickycobra]

Level safe yourself the headaches that arise with a sloped floor.

 

[dcovey]

I would think it all depends on what you do in the garage..

I work on race car chassis. So I want mine as level as possible to allow me to easily work.

If I was to wash a lot of cars or that type work I would want it to slope towards where ever I was to drain the water (drain or door).

Mine is slick and level, and I use a squeegie (?) to push the water out..

I had a friend with a drain in the floor that used to wash the oil dry and dirt down the drain. It stopped up and was a pain to get cleaned out.

Just food for thought.

Dave

 

[Steevo]

I wanted to do a floor drain down the middle of my shop, but the grease trap requirement was a PIA, and after thinking about trying to roll a creeper across a grate, and fish dropped nuts and small parts out of the drain, I decided against it.
I had my slab poured level (24x40), and the only issue I have is that in pounding rain or when snow is blown up against the roll-up doors, I get some seeping water inside that just sits in a puddle near the door, because it doesn't slope.

 

[Falcon67]

What he said. Mine is flat (well, now has a crack and a 1" slope on the east side) and I liked that. For washing things, they get kicked out the door.

 

[larry_g]

Dry workshop = flat and level
Wet parking = flat and sloped

I have what I consider a workshop and I did the flat and level.

lg
no neat sig line

 

[59 wagon man]

level on perimeter 1/8" pitch would be plenty towards floor drain this would reduce the pitch on the floor if you have a drain. near door def pitch out towards door

 

[fflintstone]

level, unless you wash inside a lot then you need a drain.

 

[mikeyr]

my shop is basically 2 garages, first one I park the motorcycle and rainy day car, second part I work in. I made the mistake of ASSuME'ing that the floor would be flat all over. By the time I got home the front half was finished and they were working on the second half, the entire thing had a slope. I raised my voice a little and they were able to fix the second half before the truck delivered that load, so the front half is sloped the back half is flat.

The sloped part *****, my 4post lift is not as stable and I have to build little wedges for each leg, things roll down hill and it just *****. My fault for assuming and not discussing it.

 

[santagary]

My 40 x 60 barn slab has a grate/drain in the middle...the slab is cut on the diagonal from the four corners toward the drain...works great

 

[Chris Adams]

Just thinking about a sloped floor makes my skin crawl. I can see me chasing 4500 lbs of tool box as it picks up speed for the door...
Or shimming all my shelving.
Or shimming my lift.

Even a tiny bit of slope means things wander or wobble.

I guess if it just for parking, and you live in snow it makes sense.

I have three concrete pads on my property, one in front of my Garage, sloped to the street, one in front of my shop, flat, one behind my shop, flat.

There was no more water on the two flat ones than the sloped one during our recent record breaking rains.
Any water in the shop gets squeegeed out in a couple seconds.

 

[Iroc-Z]

My shop at work has four bays double deep. Eight lifts total. Trench floor drain is in the middle. Both floors slope to the middle. I would highly recommend doing this. You don't need much slope and the water goes to the drain. As for leveling a lift its no more then 1/8 spacer. As for tool boxes. We put the front wheels on a 1/16 spacer. Problem solved. Never have a car even roll when out of gear. I would not build a shop without sloped drains.