CMU block foundation construction

This block foundation was observed in a crawlspace. The exterior of the wall is coated with cement stucco so the block was not visible. I question the integrity of wall. The house is built out in the country away from any city ordinances. Is this structurally sound? No mortar in some cases, just a dry stack. This is a first for me. Any thoughts would be appreciated. I’ll be recommending further evaluation by a foundation specialist.

Describe: Block wall was observed in a crawlspace foundation. The exterior of the wall was coated with cement stucco so the block was not visible from the outside. Observed: Blocks were laid in a stack bond pattern. No mortar in some cases, predominantly dry stack… add any other observations, like blocks out of place, visible light between courses, footing condition, etc. Recommendation: Lack of mortar between the block may result in displacement of foundation blocks. Monitor for movement or displacement of blocks.

It is what it is!

Looks like a repair, and someone just grabbed some block and filled in an opening.

My take on that is it looks like the foundation initially was mortared block columns, with dry stack block filled in later. Foundation built in stages - or as you said repaired. Hard to tell from a single picture…

From the picture, the condition and depth of the footing is unknown but is quite important.


Agreed, possibly to access that drain pipe or an old access opening they just filled in with dry stack.

I am curious though, is this an old house on piers with CMU filler between piers?

The house was built in 1995 (47 yrs old) and was a listed at 1,504 sq ft. However, the area with the CMU foundation is less than that as there is an addition of about 300 sq ft that was added outside of the foundation. The owner was in construction which accounted for a lot of different applications on the inside (Masonite paneling on a wall, lots of different shiplap, wood paneling on the ceiling, etc.

Here’s a couple more photos. I suspect the reason for the cement coat on the exterior was to “fill in the gaps”.

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That looks like a beam. Which makes me curious about how much of the CMU block is actually load bearing. Not that you have to make the determination. Going on what I see, I would elevate it to a foundation contractor.

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Dry Stacked concrete masonry wall is an acceptable method if done according to the specifications.

Here is a link form the National Concrete Masonry Association:

Must be NEW math! It’s either 27 years old OR it was built in 1975.

Yeah, I was a little under the weather yesterday. The house was built in 1975.

Dry stack blocks are specially made to interlock. Although that is not visible each course is typically staggered just as in conventional work. Block laid as pictured, even if interlocked, create a weak vertical joint between courses.

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Be sure to mention that PVC drain pipe, which the blocks seem to bear on.
As the soils shift over time, the pipe can be crushed cracked or distorted.

Stack bond is used in many commercial buildings, like schools, etc. Both require vertical core fill and horizontal bond beam components be present. As a HI, in any CMU foundation, it’s impossible to definitively determine if horizontal bond beam is present. With significant inspecting of the top course, one can guess whether vertical core fill is present. The core fill at the anchor bolts may extend the full vertical height of the wall, or it may not, so it’s a guess.

We are not here to recommend best practices, but to report on what is present. So long as the footings are proper, I don’t see any issues structural with this foundation based on the images presented.

From my construction knowledge as a GC, I believe bond beam is typically placed mid wall height and at the top course or one course below. I believe vertical core fill is every six feet. Many foundations are built with these components missing.

In this case, horizontal bond beam blocks are very likely not present. The mortared piers may or may not be vertically core filled.

I see a few


Thanks everyone for your feedback! I appreciate the additional info and for catching the things I overlooked (PVC pipe).

Michael, this is the first time I’ve heard of a horizontal bond beam. Would that help to keep the horizontal alignment correct? If that’s the case then I think the first photo would indicate a lack of a horizontal bond beam. Is that an assumption I can depend upon for further inspections? Thanks a bunch!

Bond beam: