Concrete Pad Slope

[JDGREEN4ME]

We are adding a 12' x 24' pad next to our pole barn. Planning on a 1" drop across the 12' width to keep water away from the barn. Is that enough? too much? Thanks...

 

[Lineman North Florida]

We are adding a 12' x 24' pad next to our pole barn. Planning on a 1" drop across the 12' width to keep water away from the barn. Is that enough? too much? Thanks...

I think it's more than enough fall for a 12' wide slab.

 

[arsenix2001]

We are adding a 12' x 24' pad next to our pole barn. Planning on a 1" drop across the 12' width to keep water away from the barn. Is that enough? too much? Thanks...

Not enough, standard slope is 2% or 1" over 4 feet. That would be 3 inches. Bare minimum on a perfectly finished pad is 1% or 1/8" over 4 feet which would put you at at least 1.5 inches.

 

[radman1]

Not enough, standard slope is 2% or 1" over 4 feet. That would be 3 inches. Bare minimum on a perfectly finished pad is 1% or 1/8" over 4 feet which would put you at at least 1.5 inches.

I am with you. I have heard 1/4" drop/12" which is the same as you recommended. That amount of slope should eliminate all/most standing water unless the cement is very uneven.

 

[JB4310]

1% would be more than enough, 2% would be to much in my opinion.

As long as that 1% can be maintained, not heave up from frost.

Sanitary sewers are at 1% so it's more than enough.

Especially if you want to work on things under there, you don't want it to be so out of level.

JB.

 

[bigtiller]

For an outside pad next to a building I would go with a 1 inch in 4 foot fall. And probably a little steeper depending on the terrain. But never any less than that.

 

[JB4310]

For an outside pad next to a building I would go with a 1 inch in 4 foot fall. And probably a little steeper depending on the terrain. But never any less than that.

That's even greater than 2%, Is this going to be a wash pad for cleaning heavy equipment?
Why would you need the water to shed so quickly?

Concrete patios where you would have furniture etc, would typically be 1/8" per foot. My stone patio is only 1" over 16 ft, and never a puddle even right after a heavy rain, of course there are joints everywhere so that helps.

For OP with a 12' wide pad, I would go 1.5 inches or a little over 1%, would provide good watershed and still not be to far out of whack to work on.

I'm speaking from experience on not having to much pitch on a pad. I built a large truck port on the side of my shop and made the slope some where around 4-5 inches in the 20 feet wide asphalt paved surface. It's a pain in the neck working on things that far out of level.

JB.

 

[Lineman North Florida]

I poured a front porch slab off the front of my house that was 20' and 12' deep or 12' out from the house and gave it exactly 1" of fall over the 12' and have never had a problem, if you were pouring a slab for a hog parlor or a skinning rack I could understand more fall, but water doesn't tend to run uphill.

 

[arsenix2001]

If you want to get technical 1/4 per foot slope is 2.1%, 1/8 per foot is 1%. 2% fall is the standard used for landscape archetecture. Will 1% work, sure but you stand a greater risk of standing water depending on the finishing job and backup during a heavy rain. You have to ask, are you more concerned with runoff/water issues or having a more level place to work? Then make the call. Either way im sure 1.5 inches would be ok.

 

[bigtiller]

If you want to get technical 1/4 per foot slope is 2.1%, 1/8 per foot is 1%. 2% fall is the standard used for landscape archetecture. Will 1% work, sure but you stand a greater risk of standing water depending on the finishing job and backup during a heavy rain. You have to ask, are you more concerned with runoff/water issues or having a more level place to work? Then make the call. Either way im sure 1.5 inches would be ok.

That's just what I was going to say. I just went out and measured some of my concrete and I am sticking to my story. 1 inch in 4 feet for a 12 foot wide slab against a building and outside. Most of my stuff is 1&3/4 inch drop in 4 feet. I work on it a lot and never had a concern but I also have a spot about 20 foot square that is level and that comes in handy at times. Its primary job is to move water away from the building. Any other use should be secondary. If we move the slab away from the building then the rate of fall could lesson depending on the intended use.