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CapeCod153 07-26-2010 10:57 AM

join new crawl space CMU footing/foundation to existing CMU basement wall
Hello everyone. I am a new to this forum but it looks like an excellent resource.

I am starting an addition for a 1 ˝ story capecod that I own. The capecod was moved about 10 years ago so the foundation/basement is “new” and was constructed with 12” CMU block and 9’ high ceilings. I do NOT have any construction drawings for the existing basement. The addition I am adding will have a crawl space under it and, therefore, the addition’s new concrete footings and 8” CMU block walls will be much higher than the existing footing.

My questions:
1) Do I need to tie the addition’s new concrete footing to the existing CMU walls?
2) If so, how is that best done? I do not know if the existing walls are grout filled or how they are supported. My research has revealed limited recommendations. My thoughts are to simply drill 2-3 holes into the existing 12” CMU walls where the new concrete footing will butt against it and epoxy/grout in rebar. To do this I assume I drill the holes, insert the rebar into the holes and then fully fill in the penetrated 12” core(s) with grout from a larger(s) hole above in the same core(s). Then I simply pour the new footers for the addition’s CMU walls.
3) Do I need to use a double "L" #4 rebar rod as the connecting rod or are the rebar ridges on a straight rod enough since I am simply trying to prevent different vertical shifting?
4) If the new footing is tied into the existing CMU walls do I have to tie some or all of the new CMU courses into the existing CMU walls, too?
5) If so, how many courses should I tie into the existing CMU wall (i.e. every other course or top and middle course, etc.)?


CapeCod153 07-27-2010 09:58 AM


47_47 07-27-2010 10:11 AM

Don't know answers to your questions, but someone will answer. It would help if you put in your location and frost depth if you know it.

CapeCod153 07-27-2010 10:23 AM

Thanks...located in Flemington, NJ and code requires footings to be 36" below grade.

Aggie67 08-04-2010 07:35 PM


If you get stuck, I do engneering for this sort of thing for a living. I'm in Branchburg. I'm doing calcs for a job right now for a house in Princeton. PM me with some contact info.

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