Re: hollow open concrete porch help
as mentioned in the private message here are some comments.
The metal you described is known as deck pan. Instead of using wood, a metal form used in pouring concrete on horizontal planes such as roofs , porches ( like yours ) etc. ---- in other words -- where there is nothing underneath to hold the concrete in place while being poured.
This deck pan stays in place once the concrete is poured and cured. Unfortunately this material does rust out , as in your case. In the use for the porch that deck pan is not likely being used for any structural reinforcement.
Your concrete should have at least 10 or 6 inch wire mesh or rebar ( which is more likely ) along with 4 " ( minimum ) or thicker concrete pad.
Based on the the width of 5 feet and the intended use it's likely fine.
If you are in doubt there's nothing wrong with contacting a structural engineer to evaluate the concrete porch. For around $300 - $500 the engineer will give you peace of mind.
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