Block foundation transition - InspectionNews

Greg Jenkins · #1 (**permalink**) 06-05-2008, 05:50 AM

I am looking for some detailed info. on the correct method to transition from one block size to the next when constructing a foundation wall. In the posted picture it appears that the block is being reduced from a 12" to a 8". Should the cavity on the top course of the larger block be grouted?
I have not been able to find any details in my construction books.

Brandon Chew · #2 (**permalink**) 06-05-2008, 10:10 AM

I don't have a reference handy for this. This is how I've seen it done.

The top course of the larger block should be either solid or grout-filled CMUs to provide a proper bearing surface for the smaller block. Grout-filled CMUs would be used if the wall needed to have rebar running vertically through the cores to tie it together. The exterior of the wall should be flush and the step should be on the interior side of the wall. This is so that the waterproofing/dampproofing can be done properly on the exterior side of the wall.

Greg Jenkins · #3 (**permalink**) 06-05-2008, 11:11 AM

That is the way "most" of this foundation was constructed. Most of the blocks were grout filled with the exception of a few. (see picture) It is though they ran out of grout and called it a day. Some horizontal rebar was visible when I looked into the block cavity.

Jerry Peck · #4 (**permalink**) 06-05-2008, 06:24 PM

First, ACI 530 requires that face shells be fully bedded. That is not possible unless that course of the larger block is fully grouted or solid.

Second, there is a steel rebar in there, so I suspect it was intended to be grouted, but they probably ran out of grout, said ' I'll get it when the next truck comes for the lintels. ' and promptly forgot about it.

The only thing supporting the face shells of the smaller block are the webs for the larger block, and that ain't good at all.