screened porch on 4 inch slab

A professional mason poured our concrete slab, did a fantastic job. I took it from there building an enclosed screened porch with poly roof panels covering the roof. It was poured on hard packed soil with perimeter screened all around. It's not attached to the house.and there are no sub-surface pilings. Thinking of winterizing it and don't know what weight the slab can handle. Not sure I'll begin this sping and would like some advice. Thanks!

 

Where are you located? What was the concrete mix used? Was there reinforcing or additives used in the mix?

You'll find out how much the concrete can support when it fails. Most patios and driveways eventually crack and fail with temperature changes, ground movement and load. Asking it to support a structure above with point loads (your columns) just adds to the stress and may shorten it's life. That yours appears to be on a thick layer of fill only increases the risk. You have to consider that nowhere in construction is a 4" (more likely closer to 3 1/2") slab used for structural purposes. No walls, posts or columns ever rest on concrete that thin. Is it going to fail right away... probably not. Will it last for years... probably. How long until it cracks... nobody knows.

The next big issue is how you plan to enclose that structure? It certainly wasn't designed with that in mind which makes sealing it up for winter more difficult and expensive. Without knowing your location I worry about snow loads on the roof since I don't see any collar ties to prevent the sides from pushing out though the modified octagon shape helps some.

 

Well, I got what I needed, a slap in the face. Kidding aside, appreciate your knowledge. I built it five years ago in Catskill, NY. The mason is a quality guy. No reinforcement was used but it is a solid 4 inches. No matter, my question's been answered. It'll remain as is. Thanks. BTW, code here is strict, as for the snow load, that was covered by doubling up all the rooftop lumber, everything signed off. .