what is a good slope for garage slab – or what is required. I was thinking of the 1/4″ per foot.
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What are you sloping it toward, floor drain and overhead door?
1/4" per foot works for either one, but you can use as little as 1/8" per foot if you're good at screeding and finishing. Remember this slab is inside the building and will not be trying to shed a lot of rain water. Now if you are planing on using the garage as a wash bay, stay with the 1/4" per foot.
Dave
no floor drain...just overhead door. I got 20' ...so that's 5" seems alot I'm thinking maybe I'll go down to 4".
btw: my own 3-stall garage has a nice puddle under every door extending in for about 6' every time it rains... we got the 4" of pitch alright... just not where we needed it..
u no ? attention to detail ?
the other thing , of course is the pad IN FRONT of the doors should slope more severly ... say 1" per footMike Smith Rhode Island : Design / Build / Repair / Restore
I'll have good slope in driveway as my garage is couple feet above street elevation.
It's a little hard to describe but around here some builders and/or finishers put about a 3/4" lip just inside the big door(s) maybe about 1/2" to 2/4" tall, 2" from the door, and the entire length of the door. It alleviates the prob you descried where water comes in under the door(s) when it rains.
You may want to check the weather stripping on your garage door bottoms. That should normally seal pretty tight to the concrete. - Unless it did that from the get-go.
i've seen the lip you described , but never spec'd it , how do they form it ? is it a metal edge ?Mike Smith Rhode Island : Design / Build / Repair / Restore
Do you suppose that lip is done by forming across for the garage slab pour in line with the inside wall line, then pouring the apron slab next day, the apron coming to the inside slab, but with its slabside elevation dropped 3/4"?
The garage door gasket comes down onto the pitched-away apron slab, and any wind-driven rain that gets under the gasket cannot climb the lip.
First let me say that around here garages are usually built by installing regular footings, and then building up brick/block foundation stem walls. If it is a concrete basement, the stem walls would typically be made of concrete. Later, after backfill, at slab time, concrete is poured inside this stem wall foundation to the desired level.
Re the lip, it's a little hard to explain, but briefly let me say that a 1x4 or 1/2" plywood (OSB) strip is laid flat in the wet concrete just inside the foundation walls to form the lip. The concrete is screeded to the high side of the 1x4 (strip) inside the garage, and to the lower side of the 1x4 (strip) on the outer facing edge of that temp form. Then, during finishing, the strip is removed.
I don't have any pics. The houses I'm doing right now don't have garages. My house doesn't have the lip because I have good pitch in the driveway away from the garage door and therefore it was unnecessary.
Why wouldn't the "mini curb" create a puddle from the water draining out of the garage?
blue
It will, - from any water that is draining out of the garage, assuming that the weather strip on the bottom of the garage door is a perfect seal - which I doubt. But then even if there wasn't a lip there the water would pool at the door. I don't know though, maybe this method isn't that great for people who might be pulling into the garage with 40#s of snow attached. It only snows once or twice a year here... For people who don't know where to to wash their cars, I can't hep them... :-) All the concrete is still pitched to the outside though. Attached is a quick sketch.
I believe the ones I've seen around here (NH) have the lip moved to just in front of the door, which keeps the door out of the puddle, while still helping to keep water from working up into the garage.
I opted for just pitching the bit in front of the door fairly steeply, so I don't have to push the snowblower, etc. over the lip every time.
Don
LOL! Thanks for the picture Matt.
I was thinking the lip was opposite? Duh!
That looks like a good method to me. I wouldn't want the bump though.
I've got really lousy garage seals up north and we get snow blowing under the door. It's no big deal though. I might have to spend 93.2 seconds each year sweeping. I think I'd prefer to sweep, than to have that bump. My grandkids would trip on it with their skates.
blue
I'd slope it as much as you can stand. Your figure of 1/4" per foot doesn't sound bad.
When they poured my garage slab in my last house, I asked 'em to slope it a lot. But they got one low spot - Right where I got out of my car.
So during the winter melted snow and rain would puddle there and freeze. So I got to get into and out of my car on a sheet of ice.
1/4" a foot is a lot. On a 20' deep garage, concrete sloping toward the big door, that would be 5", and 6" on a 24' deep garage. Here a more typical slope would be 2.5 or 3". Of course we don't have to deal with heavy snow, etc.
BTW - how about filling out your profile so we have an idea what area you live in. You've been around long enough...
PS: there is no IRC code requirement - or at least not the the IRC2000 that we use here.
Edited 11/8/2005 7:29 am ET by Matt
i like a 4" slope on a 24' garage... but the most critical part is the 10' near the overhead doorsMike Smith Rhode Island : Design / Build / Repair / Restore
I guess that would be 1/6" in a foot. Not sure my concrete guy could deal with that "direction". :-) 4" sounds good to me though. Much more hould have my sockets rolling out into the driveway :-)
done
In my 36' deep garage that I'm building, I had the finisher run the back half flat, then sloped the front 18' about an inch toward the door. He said that wouldn't be enough, but I didn't want a lot of slope.
I'm still building, but when we've gotten rain, it's drained out pretty well - there's a couple spots where I get 1/8" or so puddling, but I've got a squeegee.
Probably won't have a door or heat in there this winter, so it'll be a while before I can tell what really happens. Don't expect to have a big issue, though. I've tubed the slab, so shouldn't have a problem with water freezing on it.
Don
Then,
When I built my 24 x 24 detached garage, I knew that I was going to be doing some race car chassis fabricating and decided to make the slab as close to level as possible. I have never had a problem with water under the doors etc. And ... the sockets stay right where you drop them :) I guess it depends on what plans you have for the building. The two car garage attached to my house probably has about 3" of slope towards the door and its not too bad.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md