Flat or sloped floor? Floor drain?

[Innovate1]

Had originally planned 4" slope over 40' length of 30 x 40 detached garage. Recently considering making it flat as I plan to use if mostly as a workshop. Have a friend who made his shop flat. It will be used for tractor parking and perhaps an RV. One option is to make the front half (toward the OHDs) sloped and the back (which includes half bath) flat. Tractor may get used a bit in the winter but is mostly used in fair weather so minimal issue with ice and water. Even with a flat floor I would want a little slope right by the doors so water doesn't come in during rain - in that case perhaps slope just the last foot or two.

Then the better half says she wants to be able to wash vehicles inside in the winter. Have another friend in another location that put a drain slot down the middle of the bay and drains to daylight. Not sure that would be allowed here. Adding all that moisture to a shop with equipment seems like a bad idea and we could just wash vehicles outside on good days or take them to a car wash (no oversize vehicles except perhaps a future modest RV).

Looking for thoughts on this and what considerations I might have overlooked.

 

[spudley]

I went flat with a slight slope at the OH doors. Also was fortunate that my floor actually turned out nearly perfectly flat as only one small "birdbath" is present. By the time I sweep that area, the remaining water dissipates within a foot or so and dries.

If you do slope I'd cut that 4" to 2". You're not hanging a gutter or a drain pipe and water will always flow downhill. Worst case, buy the wife her own personal squeegee.

 

[BillK]

When I built my 24x24 detached garage I made the slab perfectly flat and level. I don't see any negative to it. I have never had an issue with water coming under the door and it is perfectly flat all the way out past the door.

My 22x22 attached garage is sloped and I don't mind it too much but it is a pain if you want to work on a car and not have it in park or with the parking brake on. I built a work bench down one side and had to custom cut everything to make sure the top was level.

If you plan on doing any type of wood working / fabricating etc you will want the level floor.

 

[John in OH]

I've always put a small amount of pitch on concrete floors that I've had poured, although not quite as much as 1"/10'. Your proposed 1"/10' is certainly not unreasonable, but it may be more than you really need for your intended purposes.

A slight pitch has never been a problem.

 

[KJINTF]

If you ever want to use tire skates on the RV
Flat is required
Even the expansion cracks make it difficult when rolling the beast out of the way

 

[BillK]

A slight pitch has never been a problem.

I really think it depends on what you are using the shop for. If you are building a 5 ft long bookshelf even 1/2" in ten feet will make the bookshelf 1/4" out of level from end to end if you have it sitting flat on the floor. You will have to compensate for that when doing any type of fabricating.

 

[Chilliwack Murray]

I have 3/4” over 32’ and that is perfect for being able to wash the floor and not have water run toward the back wall. It’s easy to get most of the water out the door with just a broom and nothing rolls on it’s own. Nothing worse than water pooled behind benches along walls.

As others have said it’s noticeable when building anything on the floor or putting up a shelf for that matter. I wouldn’t go any more than the slope I have. I’d still have a slope because I like to wash the floor after dirty brake or clutch jobs or just muddy vehicles but maybe slightly less like 1/2” over 32’ if I did it again.

 

[My Old Tools]

Flat for me. Mine's a shop, not a garage. Don't want water around my tools.

 

[MSPoirier]

A slight pitch would be helpful at times but I've always prefered a flat floor and a good squeegee on hand! Just don't make the same mistake I did, make sure you pitch outside on the garage door apron or water could seep in during heavy rains

- Sam

New England Region

 

[Pluribus]

I'd rather deal with occasional squeegee necessity vs. not having a level floor to work on in a shop.

As for a floor drain, I don't want one. Ruins a flat floor. If it's a long, trench style, then it ***** to have to roll equipment across it. **** like sawdust, dog hair, and fir needles will accumulate in it at my place which leads to not a fun cleaning requirement.

 

[matt_i]

I wish I would have identified the specific landing spot for the garage door and made a pocket 1/8" lower than the floor right there. Wind driven rain "leaks" under the gasket a little bit and I think that would help it out.

I don't mind the squeegee-ing from time to time, I really like the flat floor that I had poured and hate the sloped portion (with center drain pot) of the existing shop. My cabinets need shimming so the drawers don't auto-open. I think the previous owner had visions of washing cars indoors.....I see you mentioned it. I would never ever do this in a building intended for tools and materials. Rust is already hard enough to check as-is and this would be a huge aid to it. Take it to the car wash.

 

[maxpat82]

I have a 28x44 garage with 2 door on the 28' wall.

I made a 14x20 "stall" sloped to a drain in the middle and everyhting else flat!

it's perfect to have the car/trator in to melt.

 

[plout99]

I wish I would have identified the specific landing spot for the garage door and made a pocket 1/8" lower than the floor right there. Wind driven rain "leaks" under the gasket a little bit and I think that would help it out.

I don't mind the squeegee-ing from time to time, I really like the flat floor that I had poured and hate the sloped portion (with center drain pot) of the existing shop. My cabinets need shimming so the drawers don't auto-open. I think the previous owner had visions of washing cars indoors.....I see you mentioned it. I would never ever do this in a building intended for tools and materials. Rust is already hard enough to check as-is and this would be a huge aid to it. Take it to the car wash.

The pocket is the way to go, I made my shop floor flat and made the area under the doors 3/4 inch lower than the floor with a slight slope and broom finish. Had several hard wind driven rains and there was no leakage under the doors.

 

[Lassen Forge]

SLoped floor and drain, tho you'll likely be required to have an oil diversion system as part of your drainage... anything from a collection box with oil pads to an actual 3 stage separator, depending on your municipal hazwaste or stormwater code.

I used to inspect and service these things... you do NOT want to deal with the wrath of the local county environmental person if you don't follow their guidance.

 

[Innovate1]

Sounds like people have strong opinions both ways. It all depends on what the space is used for. Since mine will be a place for a tractor and mainly a workship (wood and metal working, very little car stuff). Thinking minor slope for the first 10 feet from the OHDs and then flat. That will still leave room for a lift in the small door section although I don't see me getting one.

I agree washing cars isn't for a building with tools. Either do it outside or a carwash.

 

[tarmy]

I am 32x56...and almost flat...

The other thing to think about is the apron. I went with no lip...as I wanted to roll boats and large mobile tools around the garage and outside for various things. I only get a little water on wind driven rain days...not much really.

I, like you, are in snow/freeze country, no drain is what I concluded...never missed it. My tractor sleeps there too...never an issue with drips. Buy a squeegee push tool if you are worried about it.

 

[theundermount]

mine is sloped, I'm always thankful when I can easily give it a clean and flush it all out, but if anything, and I mean anything can roll kiss it goodbye as it will makes its exit right out the front door and down my driveway lol

 

[CraigStu]

The concrete in my add on garage had a special technique to deal w/ water possibly coming in under the door. Picture your 2x8 (or whatever) on edge across the door opening to keep the concrete from flowing out the door. The top edge marks the final level that the floor will be brought to. Now, grab a 2x4 or 2x6, and lay it horizontally so it's top surface is flush w/ the top edge of your form and screw it to the inside of the form w/ lags. Now when all is done, there is a 1.5 inch deep by either 3.5 or 5.5 wide pocket that the door fits down into. So the door seal is actually 1.5 inches below the floor level. Also the lead-in apron is at the lower level of that pocket.

 

[2level]

I went with a flat floor except for the back portion of my L-shaped garage, which is sloped to an exterior channel drain located outside the entry/man door. I like to clean the floor with soap and water about once a year. I usually wash one or more of our vehicles at the same time -- I'm told that this dual usage of water helps save the planet!!

Pick a hot, dry, and breezy summer day and moisture on tools, etc. won't be an issue.

 

[Matt 330LS]

The attached garage at my place has floors that slope inward toward a round floor drain. My wife loves it because snow/ice/rain that runs off her car hits the floor and runs right to the drain. It drives me nuts because because you have to custom level anything on the floor and everything round rolls towards the drain. I built a 28x32 detached several months ago and that floor is flat with a slope at the overhead door. Couldn't be happier with the decision and I can just sweep/squeegee out any slush or water I need to.

 

[Innovate1]

I went with a flat floor except for the back portion of my L-shaped garage, which is sloped to an exterior channel drain located outside the entry/man door. I like to clean the floor with soap and water about once a year. I usually wash one or more of our vehicles at the same time -- I'm told that this dual usage of water helps save the planet!!

Pick a hot, dry, and breezy summer day and moisture on tools, etc. won't be an issue.

IMHO, if it's a hot, dry day it would be fine washing it outside. I think the idea of a place to wash the car was so it could be done in the winter. But there are car washes for that. We don't have THAT much snow and freezing weather here that it can usually be done during a warmer spell when things melt.

And this building isn't for the cars. It's for all the stuff in the attached garage (with sloped floor) so the daily drivers can go in the attached garage.

Just poured the footings today. Foundation wall scheduled for Jan 2.

 

[2level]

Innovate1 - Just sharing my experience re: to slope or not to slope floors. Indoor washing isn't necessarily a winter-only proposition. And since best practice is to wash vehicles in the shade...

Anyway, it sounds like you have a nice build going. Happy New Year.

 

[aventino68]

From a newbie moving to a cold climate reading the forum I think you have to split between areas you will park a daily driven car that’s covered in ice and snow that has to melt and go somewhere. And garage areas that you’re going to keep closed up and work in through winter.
So I’ve ended up with two bays where the winter beater vehicles get parked in the garage attached to the house and they both have centre drains in them. Then the rest of the garage/workshop is flat with no slope and in the off chance I get a wet vehicle in there I’ll squeegee the floor out. But I have no toolboxes or anything on the areas that have a gradient.

 

[Innovate1]

No daily drivers here. They go in the attached garage that has slope. I might 1 time a year move the tractor in with some snow on it from plowing the drive but that's going to be rare. I decided to go with flat with about the first 2' sloped to help keep the rain out.

I put a floor drain in the very back by the half bath on the plan that was approved. No mention of needing a grease trap, at least not yet, and I don't think they will require it. I am planning to put the water heater on a small mezzanine above the half bath and hang the furnace/AC so was going to go with elevated traps for those to keep the hoses and such off the floor.

So am mulling over if I need a floor drain at all. Think I will go for it as it will allow a future mop sink or be a drain for possible future floor level stuff (not sure what). I will have a large shop sink but a floor one is sometimes handy. Thoughts?

 

[Jackfre]

I did a flat floor on my 30x30. I put a 3/4" lip at the large door and have had no water intrusion. Floor drains can be problematic. It depends upon where you are going to terminate the drain. You don't want it in your septic.

 

[Prospecter]

My 24x30 is flat floor, no drain. My cars live outside, unless I pull them in for service, but my tractor lives inside. I like not having a drain when I spill, as during an oil change. I do not like it in the winter, when I am done plowing and pull the tractor into the garage. The snow melt (Maine Coast) produces enough water for me to wet vac my garage 3-5 times a year, and leave the tractor outside to melt off as much as I can. I think if I lived in St. Louis I would be happy with the no drain solution. Here, I kind of wish I had gone with a drain, but it's manageable. If I were further north, I would be retrofitting a drain.