Suspended slabs

[palmettoinspect]

I ran into these suspended slabs at my inspection today and need some help understanding them. Home built in 1984.

The slabs are installed over treated plywood and supported on the perimeter by concrete block and bricks. There are piers installed in the middle of the forms with steel lintels spanning from the piers to the perimeter block wall. The piers are not in contact with the plywood. The slabs are exposed to the exterior and not completely covered. The slope isn?t very good for shedding water. The steel lintels have rusted out at the ends and the plywood is beginning to rot away. There?s no major movement with the slabs and only minor hairline cracks.

My question is what?s the plywood doing? I?d imaging it?s just a form that wasn?t removed after the slab was poured.

Does the steel need to be replaced and are the piers suppose to be in contact with the slab?

Are these suspended slabs just junk all together?

Thanks,

Kiel

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[Jim Katen]

Most of your questions can't be answered without knowing what kind of reinforcement is inside the concrete. You're not about to be able to do that in the course of a home inspection.

I've seen slabs like this that were 100 years old and completely self supporting. I've also seen them crack and fall apart because they weren't properly reinforced or because the reinforcing metal rusted.

I'd be very suspicious of a house built in 1984, it's too close to 1981 for my taste.

When I run into these and I see rotting wood I recommend that they hire a contractor to remove all of the formwork from under the slab, determine what, if any, permanent support is needed, and install such support.

[Marc]

We build a few houses in Atlanta in the late 80's, early 90's that way. Substituted 1/2" cdx for 3/4" subfloor then later a contractor would come and pour 2" of fiber reinforced concrete mix over it. The boss said it made for a very good floor. Very quiet and solid to walk on. These were for upscale homes.

This was with the joists at 16" centers.

Marc

[Tom Raymond]

It needs more than adequate support, it leaks like a sieve.

[Jim Katen]

It needs more than adequate support, it leaks like a sieve.

Perhaps I'm misunderstanding the situation. The ones that I see are always porches or elevated patios. If they admit some water, it's not usually a big deal.

Is this post about a concrete slab over the entire first floor of the house?

[kurt]

No, he described it as exposed to the exterior.

I see pretty much what Jim said; sometimes they're just fine after 50 years, other times they're collapsing after a couple years.

Either way, leaving the plywood in place is a dogmeat methodology. I wouldn't have anything good to say about it.

[palmettoinspect]

It needs more than adequate support, it leaks like a sieve.

Perhaps I'm misunderstanding the situation. The ones that I see are always porches or elevated patios. If they admit some water, it's not usually a big deal.

Is this post about a concrete slab over the entire first floor of the house?

No the suspended slabs are just the concrete patios/porches. Three total on this particular house. The home is wood framed. They basically don?t have any support in the middle other than the lintels which are rusted out.

[Jim Katen]

No the suspended slabs are just the concrete patios/porches. Three total on this particular house. The home is wood framed. They basically don?t have any support in the middle other than the lintels which are rusted out.

In that case, I'd just say what I said in my first response. If the water entry seemed to be a problem, I'd add something about preventing water from getting into the assembly.

In the pictures, the steel angles don't look all that badly rusted. Where there others that were actually rusted to the point that they were unable to provide support?

[palmettoinspect]

No the suspended slabs are just the concrete patios/porches. Three total on this particular house. The home is wood framed. They basically don?t have any support in the middle other than the lintels which are rusted out.

In that case, I'd just say what I said in my first response. If the water entry seemed to be a problem, I'd add something about preventing water from getting into the assembly.

In the pictures, the steel angles don't look all that badly rusted. Where there others that were actually rusted to the point that they were unable to provide support?

Jim, Thanks for your help. Yes the steel is badly rusted at the ends to the point where they should be replaced. I've circled one of the pictures to show you. I think your right to suggest removing the wood and determine what support is needed.

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