CMU Wall Offset

[Einsteim]

I have an architect that wants to offset a CMU course as the wall comes up out of the grade on a building. The offset, or step, is 7/8" and I cannot find much information on whether that is ok. It seems excessive to me since the majority of the bearing weight from above is carried in the face shell that will not be supported by anything below. Comments or references on this subject would be appreciated. See attached detail.

 

[Teguci]

I'd say no. Testing for CMU is for blocks stacked full on top of each other. To even start to consider this option I would want to provide a transition detail which would include a bond beam top and bottom (or a concrete grade beam).

 

[jike]

This may be feasible as long as you use solid (or fully grouted) units above and below the offset and all the related stresses check out. Comply with all requirements for corbels in ACI 530.

 

[Einsteim]

That was what I was going to propose...fully grouted below for sure, and likely a course above the offset..thanks

 

[patswfc]

Whats the reason for the step at this location?

 

[jike]

Make sure the architect places cont. flashing and weeps at the offset.

 

[Einsteim]

The reason for the offset is 1) to keep the brick face lined up with the foundation wall and having a minimum width collar joint. 2) to cover the unslightly void where the slab and rigid insulation are adjacent to the block wall.

I am not sure how many architects are using this detail with the insulation, but I hate it.

My proposal to the architect is to step the brick out 7/8" and keep the inside face of CMU lined up. Problem is, the insulation void is visible and he doesn't like that.