Cracked monolithic slab is keeping me up at night.

[CivilTom]

I've owned a 2 flat building for 7 years now. The 2 flat sits on a perfect rectangle monolithic slab on grade. The slab is cracked about 1/5" right down the middle of the slab (short path of rectangle). There isn't any water penetration. Now although I did not know about this crack when I purchased the building, I also did not notice any significant signs of settlement for the past 7 years. The building is 60 years old. I'm concerned because it's a crack in a monolithic slab which I would assume turns it into a structural crack. Is it possible it is "dormant" and that had it been active I would have seen major building changes in the past 7 years? I installed new vinyl and forgot to take a photo, but this is essentially how the crack looks.

 

[SWComposites]

is the photo of a random different slab from the internet??

sounds like you need a local engineer to have an look onsite.

 

[RPGs]

SWComposites is correct, pull together any construction documents you have and get an engineer on-site to assess and draft you a report. Unfortunately, there are way too many considerations that aren't addressed in your post.

 

[CivilTom]

You’re right. I should have a report drafted. Any advice on who to hire? Is it just a local licensed SE? Or “foundation specialist”?

 

[Lomarandil]

Slab on grade... Crack near the middle... Is there any evidence for it to not have been a shrinkage crack from the original pour?

 

[RPGs]

It can be difficult to vet engineers for their experience and confidence in a given situation, but I'd like to think any licensed PE or SE with basic experience in concrete inspections could review the information, rule out some possibilities, and get you a report for this to address your concerns. I wouldn't say they need to be a specialist.

 

[hokie66]

If this is a slab on ground, it is undoubtedly a drying shrinkage crack which has been there for a long time, and in your lingo is ‘dormant’.