There are a lot variables here to consider.
- Does your slab have reinforced wire mesh?
- How thick is your slab?
- You'll need to form a 8' wide by 12" high concrete wall around the entire perimeter excluding doorways, and your slab will need to be thick enough to not only support the cement, but also the wall framing, sheething, siding and roof load as well.
Without being there, it's a challange to steer you in the right direction here. How about some pictures? The cement wall is to prevent any water from seeping in.
I would highly suggest getting a contractor out there to assess the situation. Find someone who you know has extensive experience (hopefully a friend or acqaintance). I know that's a foregone conclusion, but I think it's the wisest approach in this case.
Reason being, hopefully whoever poured the slab, they formed it properly to have the carport inclosed in the future. If anything, the posts that support the roof most likely have a pier underneath going down to a depth according to code for your area, and the slab should be at a the thickness according to code as well. (maybe 6-8"'s) and IS reinforced to support the weight of the vehicles. Considering that the slab was poured after the house was built, I highly question if it was done properly. That's just my "gut feeling".
In any event. most contractor's are willing to go out and give you an estimate. Give that a try.
Good Luck :wink: