CMU Block Crawlspace Foundation - Openings?

I was inspecting this crawlspace and see these openings where the condo unit separates from the neighbors crawlspace. Can someone please tell me what this is for?

Thank you,

Maybe to get some air moving?..I see some of what appears to be moisture on the blocks to the right.

Maybe to let the cat use the neighbor’s crawlspace as the litterbox?

Man, your guess is as good as mine.

I would just note it and move on, Mike.


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Yes I saw that too, the efflorescence in the first picture on the right side. Should I say the foundation is damaged and need further evaluation by a structural engineer?

Ventilation? Seems like shoddy work for ventilation. Ventilating from one units crawlspace to another?

No. You do not need a structural engineer for that small hole.

Narrative example:

There was a small (approximately)10" x 10" hole punched in to the block wall separating the units. I recommend asking the owner about it, having a foundation contractor assess it to determine its reason and make a proper cure for that reason e.g. air movement?, etc. or sealing it closed.

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Perfect. Thank you Larry.

Foundation Opening for Venting Circulation.
Requires a protective vent cover to impede vermin, rodent and insect entry.
Soil requires vapor barrier.
Rim joist not insulation
My 2 cents.

Not efflorescence.
Staining on the lower courses. Not efflorescence. Not wicking. Atmospheric staining. Think circulation.

Yes indeed. That’s because the “fix” is reactive, not proactive. Likely - long after the original construction - moisture problems were detected. Someone apparently realized that the interior crawlspace of the building was holding moisture and wouldn’t neutralize. The common “fix” (which sometimes works) is to open the crawl to the end units to increase cross ventilation. Of course it’s up to you to determine if it’s working.
I see it fairly often, and find that it’s usually either underdone (and requires some mechanical assistance), or it was done too late - and the previous moisture damage was never repaired. And SOME of them are doing just fine.