My early 70’s house had a single arched entry carport that my car couldn’t fit in. It was built-in, using salvaged materials, lined with timber from an old wooden horse float and a raised floor using Bunnings tongue and groove sheets, covered in verge collected vinyl plank flooring. It has a mezzanine storage area, part of which snuggly fits a single mattress, which is handy. The room has serviced all manner of uses over the years. Currently it’s used for storage and sewing.