Thread: Concrete floor slab, above basement.

I am considering purchase of a 1957 vintage house that was origonally built with a crawl space, but has an add-on section where a basement was dug and the floor above it is an elevated concrete slab. My inspection ( I am a retired engineer) from below looking up, reveals that much of the rebar is exposed and very corroded. Aparently the rebar was placed on the bottom of the formwork. The concrete was obviously not vibrated, there are voids and exposed aggregates. Under the center of this slab is a stack of concrete blocks, resting on the basement floor slab, that I suspect was added to either prevent some observed settlement or movement of the floor slab. My question is, would a certified Home Inspector be qualified by virtue of Home Inspector training be qualified to recommend whether this is a fatal flaw and a suitable reason to pass on purchase? Or woud a HI recommend getting a structural engineer to evaluate? And, it seems this type construction is very unusual. Why wouldn't the add-on floor have been built using conventional wood floor joists?

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Originally Posted by Robert Cromwell

I am considering purchase of a 1957 vintage house that was origonally built with a crawl space, but has an add-on section where a basement was dug and the floor above it is an elevated concrete slab. My inspection ( I am a retired engineer) from below looking up, reveals that much of the rebar is exposed and very corroded. Aparently the rebar was placed on the bottom of the formwork. The concrete was obviously not vibrated, there are voids and exposed aggregates. Under the center of this slab is a stack of concrete blocks, resting on the basement floor slab, that I suspect was added to either prevent some observed settlement or movement of the floor slab. My question is, would a certified Home Inspector be qualified by virtue of Home Inspector training be qualified to recommend whether this is a fatal flaw and a suitable reason to pass on purchase? Or woud a HI recommend getting a structural engineer to evaluate? And, it seems this type construction is very unusual. Why wouldn't the add-on floor have been built using conventional wood floor joists?

Rusted re-bar and a stack of concrete blocks resting on the slab that's supporting another slab. You need a structural engineer.
Home inspection training teaches us how to recognize and identify a defect, and who to defer it to.

Dan's explanation is dead on. We are generalists. Even a PE that becomes a home inspector will still be a generalist outside of his/her specialty. While we can and do often make recommendations that don't need a second assessment from a specialist, we often see things that call for evaluation by an appropriate specialist. In your case, I too, would call for further evaluation by a structural engineer.

Re-bar has to be in the middle of the slab to be effective. Which is basic construction knowledge which be attested by most contractors, but for court get the engineer opinion.

Was the block sitting on a footer?

The issue of "certified Home Inspector " is a discussion in itself. By HI training from some organization from a training video or online course I would say not qualified. By virtue of a class in Home Inspection as part of a state licensing, I would say not qualified. If the HI had the practical experience in the correct use of concrete construction, I would say qualified. But if you want to go to court get the structural engineer for the opinion.

I question what you meant by "certified" in conjunction with Home Inspector. There is licensing and then there is the created title of "certified" which really has little value other than as a marketing ploy to puff up appearances.

Typically a licensed Home inspector has little education and experience for the opinion that you require. The HI can/should recognize that something is wrong and direct you to someone with the professional experience. A contractor can give you an opinion but if you want real recourse for the opinion I suggest a structural engineer. Make sure you know what you are getting into with this property.