Porch structural question

Did a house today with an enclosed (non-dirt-filled) porch at the front of the home. When they poured it, they used a plywood form beneath it. House was built in '77. The plywood is rotted and there is water getting in from somewhere I couldn’t determine (they actually had a drain pipe rigged to the front porch wall to accumulate the water that’s getting in). Water intrusion into the crawl space is an issue I’m comfortable addressing.

However, is there an issue with the plywood rotting? I couldn’t tell if the porch was flashed. The house band sill on the other side of the block porch wall was OK…no sign of decay. Comments appreciated.

Picture 1 shows the front of the home.
Picture 2 shows where the siding is covered by the porch slab.
Picture 3 & 4 show the plywood beneath the slab.

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What we usually see is one or more of following,
…some sort of opening(s),gap(s) etc above/along/in the porch cap and-or…

Hard to tell from exterior pics…if its not condensation then some of the
openings we`ve seen are
…in the cap,like small hairline cracks or
…small,tiny openings where those white posts are in pic 1 or
…if pics 3,4 are right under the front door then,something is open/amiss
in this area around the threshold

and…drain pipe ‘rigged’ to front porch? Do you mean this pipe is IN the slab/porch cap,
like some sort of drain?
You could run a water-test w/hose to find any possible exterior openings that allow water to enter.

I am amazed at how ignorant some builders are…especially the ones when questioned about the installation of a product will respond that “we’ve been doing it that way since my grandpappy was building.”

They simply never learn proper building techniques…in regards to the plywood, it is common (although wrong) to use plywood as a form to swing a concrete a porch unless the plywood form can be removed as in the case when doing poured basements with oiled plywood forms otherwise it will eventually rot as is evident with your inspection…I suspect that is where these brain surgeons have gotten the idea or they are simply cheap and don’t want to pay for the metal forms and steel piping. I write it up as a condition that can promote an environment for wood destroying insect but an even more concern is the structural integrity of porch or area in which they are swinging the concrete.

Usually when you come across something like this you will also find improper flashing around the bandboard (header joist), structural concerns from not properly supporting the weight of the concrete underneath, and just general concrete problems as is the case with this inspection.

Concrete poured against wood siding is simply moronic; with vinyl siding it is wrong as well…(I had an disagreement with a builder over same)…being that vinyl siding needs to be able to move as in accordance with nailing instructions of same.


On a side note about bandboards (header joists) the interior band may be alright but that does not say anything about the outer band, (band joist are usually doubled)…Im not saying the outer band in this case is decay but it should be noted that simply because an interior band appears to be fine should not lead one to conclude the outer band is fine as well…as a builder I have had to repair many outer bands where the interior band was still intact…just becareful how you word that part of the report…don’t give your blessings to a system or component of which you can not fully see or inspect.



Jeff, thanks. The wood siding in the concrete has been that way for 30 years. No sign of decay. I can’t see flashing: uninspectable because of the construction technique. I referred it to a contractor to determine the source and severity of water entry.

Once the plywood dedcays enough to crush, the slab will drop the thickness of the plywood, and so will anything thde slab supports.