Garage slab flat or pitch?

Finally getting ready to break ground on my new garage!

Quick question about the floor slab pitch. Architect says standard is 1/4 inch per foot toward the door, and has never had anyone do anything different. Concrete guy recommends a flat pour. Im not planning to use the garage as parking, so it won't see the snow melt that most garages would on a regular basis, but I'd still rather not have water pooling.

Is the concrete guy just being lazy? Or does he have a point? 

27deepx31wide, plan to use space as workspace, will have car lift, etc. Some storage of cars, but not driving in and out on regular basis. We have attached garage already for that.

My garage is pitched two inches over 26 feet and water still pools in places. I'd go flat next time.

What really annoys me is that my concrete guy smoothed everything out and then added small grooves eight inches from the door end so "wheels don't spin when it's wet". It holds the dirt and water and looks like E36 M3.

I went flat.  I did my slab to Texas Highway Department specs.  Probably the only uncracked slab in Arkansas.

I'm no expert and really have no clue as to what it should be.  But a quarter inch per foot is 1 inch every 4 ft, 2 inches every 8 ft and 4 inches at 16 ft, that seems like an awful large pitch for a garage floor.

 Anyway at that pitch you should always be able to find your 10mm socket. It'll be resting against the garage door every time.

I'd make it flat and buy a big squeegee. 

lrrs said:

I'm no expert and really have no clue as to what it should be.  But a quarter inch per foot is 1 inch every 4 ft, 2 inches every 8 ft and 4 inches at 16 ft, that seems like an awful large pitch for a garage floor.

 Anyway at that pitch you should always be able to find your 10mm socket. It'll be resting against the garage door every time.

 

That is essentially the concrete guy's argument. That at 1/4 inch per foot (or even 1/8 inch), over 27 ft you have a noticeable pitch, and it may not drive water out as well as you would want it to. Downside of 7 inch diff front to back is worse than upside of water maybe migrating to the front.

It's good to hear that flat floor isn't totally abnormal.

I've had both.  I suggest a flat floor in a working shop and a slopped floor in a garage used for parking.  If it's flat you will need to squeegee water out whenever you park a snow or rain covered car in there.  If that's going to be a rarity then go with a flat floor.

Flat. Pitch it toward the door and it freezes you're locked out (or in).

My garage is 24x30 the short way (3 cars wide, 24 ft deep) and its pitched approx 4" over that distance.  It doesnt bother me.  Sometimes my toolboxes roll, I can either set the stops on the casters or stuff a block of wood under them.  Never had a drainage problem or a freezing problem (Wisconsin, so we have plenty of draining and freezing)

Its not enough of a pitch that a car in neutral will roll without a push.  

More than anything I am pissed the expansion joints are right where I want to put my lift so I need to cut out a big section and repour.  

Check your building code. If it is attached to a residence it is required to pitch towards the main door. 

You can design and prepare for either, but the dudes placing the concrete have you by the nuts.  If the truck has a bit too much, or a bit too little, you will have a hump in the middle, or a hollow.  If he doesn't care enough in floating and trowelling, you will have puddles all over the floor.  Hire the right guy, make sure he knows you care, and you will end up happy.

My garage and shop are both pitched toward the door. Water does not run out unless there is a hose running inside. Water off your car will never run out, but it is helpful if you want to wash out the garage. If I did it again I would have a flat floor in my shop, it doesn’t matter where we park the cars.

My 15 year old attached garage, and my 4 month old pole barn are both flat. They do have a ridge about an inch high that is tooled into the concrete just inside of the overhead doors to prevent any runoff from seeping in from outside. Basically the entire floor is about an inch higher than the drive. Water from vehicles hasn't been an issue yet. If it becomes one, I'll get a squeegee or add some grit and a sealer on top of the concrete.

For what you are doing I would suggest flat.   I just had a flat slab poured in the workshop area and did an alignment for the first time.  It was great. Also makes a future lift install easier without the need to shim. 

They are typically pitched in snow regions, and flat in areas without snow.

I've lived in both areas, and built both ways.  I would definitely build flat, unless you are building a commercial style space with floor drains.

Duke said:

Check your building code. If it is attached to a residence it is required to pitch towards the main door. 

That's partly true.

The code says the area of floor used for parking of automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway.

It doesn't say what pitch, what liquid, what viscosity, what drain rate, what the purpose is, nor does it say liquids should successfully drain out of the building.  It only says "toward" the main vehicle entrance.  

If the liquid is gasoline or motor oil, it would not be environmentally appropriate to drain it to a floor drain or the the ground outside.

I would suggest that it is pretty much undefined, and therefore unenforceable.  Code enforcement officials don't generally try to enforce it to the code.  They enforce it to the plans, and let the architects decide what all that crap means.   

I debated this for quite a while for my workshop, and ended up going for flat.

For what I do, flat and level is far more conducive to vehicle fabrication and wheel alignments than sloped.

On the -house- garage, for the dailys, it's sloped and I prefer that - all the winter schmoo runs OUT of the garage and down the driveway.

I bought a big squeegie for the shop, for the few times water needs to be coaxed away.

If you do any fabricating a very flat floor is nice for layout. Also, if you scale a race car a slope throws the numbers off, and when you roll the car on and off the scales it wants to keep rolling which is a royal pain. I would agree with plumbing slope (1/4 inch per foot) for a parking area and pool table level for a working shop. 

Also consider a couple anchor points poured into the slab. In my old shop I had a couple of loops of heavy round stock poured into the floor sitting in depressions. You can use them for frame straightening or a press or whatever. I didn't do that for the current shop and I miss them.

Flat makes for a better surface to lay out chassis when building hot-rods.

1/4" per foot means that whatever you park in there better have a working handbrake. 

I'd go pitched, but to a lower angle.  I had a flat floor at the warehouse and found it a pain when we washed the cars or had fluid spillage.

No input other than to say that it is exciting that you are breaking ground!

Thanks for the feedback all! Yes, groundbreaking is officially today. Very excited. I should update my other thread. I'll stick with flat and make sure the concrete guy does a good job. I'll also quick check that flat won't be a problem with the city, but it is detached so it shouldn't be.

Have him pitch it towards the center, with a groove to catch all the 10mm sockets. 

When my contractor poured the "Alaskan Slab" ,  pitch wasn't even discussed.