I have an attached carport that I'd like to add to my shop space for my computer/office space. Currently, it's open with gravel on dirt. The shop is concrete, and I'm trying to find the most economical DIY solutions to get a floor covering for the carport to add it as functional shop space. Poured concrete would be ideal, but I don't know how I'd do with b/c the structure is already in place, and it's a huge area to cover by myself w/out paying for a cement truck, which is probably out of my budget (any idea how much for 3-4" deep in 250sf?). The top contender right now is a vapor barrier, PT 2x4's in a decking-type frame, and plywood on top (maybe with laminate over that). Any advice?