Footing and CMU laid on a Slope

[marinaman]

I have a site wall that I designed that steps to follow the slope of grade. The wall is to be used as a sitting wall.

My intent, and my details, show the footing stepped with the slope, and once the CMU is laid atop the footing, the top of wall steps, every so often, to provide a horizontal sitting surface.

The GC has poured the footing sloped. Then, he laid the CMU sloped. The top of wall, right now, slopes. In all these years, I’ve never seen a GC try and do this. I have no idea how he plans to get the top of wall, level, at the lengths I’m requiring it to be level.

Per the IBC code, it appears to me that the top of footing must be level (1809)

Do you guys know of any code provision in ACI 530, or elsewhere, that requires running bond be laid horizontally? I’ve been looking, but don’t seem to be able to find anything.

I’m trying to be sure I know all the code provisions about sloped top of footings....and sloped running bond...before I try and make all this work out.

Any information would be appreciated.

 

[racookpe1978]

What is the slope, length of wall, height of wall, purpose (basement, retaining wall, shed, crane foundation ...)?

 

[marinaman]

The length of wall is approximately 70'. The slope is 2%. Height is 4'....with 30" above grade, so people can sit on it. Its a seating wall.....out on a site. Its for a garden park.

Is there a code provision that does not allow running bond to be laid on a slope?

 

[dik]

Better to step the footing... Did a 747 hangar in Lesotho and there were windows added over the machine shop area... they sloped the windows to match the shed roof... did it ever look wierd.

Dik

 

[Ron]

ACI 530, Section 3.3G Site Tolerances, paragraph 2.Elements....allows only 1/4" in 10 feet variation from LEVEL, with a maximum of 1/2" total.

 

[hokie66]

The contractor did not follow your details, so he should take it out and do it again if you insist.

But the contractor probably has a good argument for sloping the wall and the seating if it is only at 2% grade. That way, the seats are at the same height all along. His way is the only way of achieving a uniform height of 30", which by the way, seems too high for that type seating.

I don't think ACI tolerances relate to this issue, and I see no reason a wall can't follow a gentle slope. I've seen it specified and done that way a few times.

 

[racookpe1978]

The bare CMU will look ugly at an angle. Have the contractor put a skim covering of mortar/stucco over the CMU to provide a clean appearance of a solid cast wall.

His expense = He failed to provide a level wall as required.

 

[hokie66]

racookpe,
Maybe in the eye of the beholder. I see no reason a sloped CMU wall would look any more ugly than a level one. We don't even know what type blocks were used. But marinaman didn't want a level wall, he wanted a stepped wall.

 

[Trillers]

Marinaman - If the wall is 70' long I would be more concerned with the supporting soil base and the depth of base course below the wall footing. If the soil is expansive you will have a long-term problem with displacement which may show up sooner than expected due to the sloped footing, even as slight as it is. If you are in a location where seismic activity is a concern then the foundation design including base and sub-base would be a significant concern.

If you have a non-expansive soil layer below the base course you might be OK.

 

[BridgeSmith]

A 2% slope will likely make sitting awkward, but an 8" transition in seating height would be awkward as well. I would suggest finishing the top with a concrete coping with soft 1" or 2" transitions. I also agree with hokie66 that 30" seems too tall for seating. Normal chair height is around 19". I have 24" stools in my house; some with padded seats and some without. The ones with padded seats are about at tall as I'd want to sit on without a foot rail, while the unpadded ones are too uncomfortable to sit on without putting my feet up, and I have longer than average legs. All of the outdoor furniture shown in my Architectural Graphic Standards have a seat height of less than 18".

 

[hokie66]

If it is already built that way, perhaps you should suggest hanging seating off the side. That way, the seats can be level and the appropriate height above grade.

But I disagree that 2% side slope is uncomfortable to sit on. Allowing 2 ft per person, that is only 1/2".

 

[marinaman]

To me, there is just too much wrong here, to allow the wall to stay. Issues began to develop regarding how the GC was going to provide the level top of wall. He was going to have to cut CMU in order to get the top of wall level, which was going to result in several triangular shapes of CMU that terminated almost as a "sharpe point".

A veneer issue was brewing also. Given the sloped footing, something was going to have to be cut in order to get the veneer joints to follow a horizontal line.

The landscape architect wanted a flat, level, wall and not a sloped top of wall.

All in all, the as built condition was no where close to the construction documents. This said, unfortunately, he's taken up the wall and footing and is reconstructing.

 

[BridgeSmith]

"But I disagree that 2% side slope is uncomfortable to sit on. Allowing 2 ft per person, that is only 1/2"."

Try sitting on a hard chair with the legs on one side 1/2" lower. Been there, done that. It takes only about 15 minutes before my back starts to hurt.

 

[msquared48]

Just have the contractor cut in horizontal steps into the top of the wall.

Mike McCann, PE, SE (WA)