Garage floor slab pitch

[ViperJon]

Hi guys
Building a new 28 x 27' detached garage (just poured footings yesterday) and a question came up. What would be considered the correct (or ideal) pitch of the new slab floor back to front? It will be 26.6 feet from the overhead doors to the back of the garage and obviously want some drainage but not excessive. I was thinking about 2"?

Is there a rule of thumb here thats will drain effectively but not feel like on an angle?

Thanks-

 

[tncatadjuster]

I used 1% when I built tennis courts, that was what was required for draining of rain. Not a fast runoff but within a few minutes it worked. Not a perceivable slope.

3" should do it.

 

[GarageEnvy]

The contractor that poured my slab claimed 3" to 4" over 20'-22' is typical. Mine is 34' deep and the rear 11' is flat. Front 22' drops about 3 1/2" and it is noticable.

 

[ViperJon]

The contractor that poured my slab claimed 3" to 4" over 20'-22' is typical. Mine is 34' deep and the rear 11' is flat. Front 22' drops about 3 1/2" and it is noticable.

Man that seems like a lot of pitch. Since I am keeping two collectable cars in the garage that don't go out in inclement weather and there will never be snow or rain in there I think I'm going to go about a 2" pitch. I really don't want to be able to see or feel the slope.

 

[GarageEnvy]

The typical is about 1/8" per foot and in my case I was fudging down on the floor side because I couldn't raise the header and I was trying to squeeze in a little taller door. Since I was re-doing the driveway it worked for me but may not be the right solution for every case.

 

[vrog]

1/4" per foot if you want it to flow freely

1/8" per foot will require some help with a squeegie/broom

So, the back of your garage would have to be 6 1/2" higher than the front.

 

[Motown 454]

I just did my 22wx26d garage with 2" front to back the water runs out fine. There are a couple of spots that leave little puddles but that is the way it was troweled out. Nothing I can't live with. there is no noticeable slope and I'm very happy with it. I have a friend who's contractor talked him into 7" in 28 feet. when it was done he said it was too steep. It even made it tuff to run shelves along the side walls. Thats 1/4" per foot its too much.

 

[folgers]

I usually recommend an 1/8 per foot. Chalk a line at that grade before you're ready to pour and see if you can live with it.

 

[LegacyIndustrial]

1/4" per foot if you want it to flow freely

1/8" per foot will require some help with a squeegie/broom

So, the back of your garage would have to be 6 1/2" higher than the front.

Vrog is on the money.

 

[larry4406]

I used to build production homes in northern va. All of our garages had 3" slope front to back. Typical depth of about 24'.

The company's standard detail was a weather lip where the garage door came down (mini-curb about 1"). This is a PIA for jacks, etc. My house was done with a weather lip; my detached garage was done without it via carefull slope change - much better.

 

[zsuperbee]

4" over 55' in mine work fine. My collectables in the back drivers in the front.

 

[Ironcrow]

Mine is dead level. If you are going to help 1/8 inch with a broom or squeegee, might as well go with level. Check with your inspector.

 

[59 wagon man]

not sure if i agree about the 1/8" per foot needing help as 1/8" per foot is an acceptable plumbing pitch which carries waste as well as water

 

[csp]

not sure if i agree about the 1/8" per foot needing help as 1/8" per foot is an acceptable plumbing pitch which carries waste as well as water

Plumbing is also confined to a pipe where the slight grade creates a pressure head. Not so much on a flat floor.

 

[Daddy_Rabbit]

my 24'x36' has a 1" pitch per 10' on the 36' length.

 

[folgers]

I reread your post and think 2 inches in 26.6 feet is fine. I'm doing a fire station floor now with that same length and fall to a center trough drain. That's what the general wanted.
When asked I recommend an 1/8 inch per foot to eliminate puddles. If you're going to epoxy your floor it will shed water better than bare concrete.

 

[ddawg16]

My garage has mayb 1/2" of slope at most (25' depth). I do a lot of wood working and having a level floor is more important and draining water....if the floor gets wet....2 min with the leaf blower takes care of the issue.

 

[MrMark]

mine is dead flat and I prefer that, actually.

 

[pattenp]

When my floor was poured the contractor said building code requires the floor to be sloped. Mine is pitched about 1/8" per foot.