I'm finally having a contractor come in and replace the rotted jalousie windows in my porch. The porch was originally open to the elements but was closed in by the previous owners years ago. I am going to insulate the short knee walls and soffits, but I was curious how I should insulate the floor? The porch is up off the ground by about 2.5ft on piers and has empty joist bays right now. I'm thinking rigid insulation in the joist bays would work. Would I need a vapor barrier if I use rigid foam?
A second question I have is the porch currently has a double column design on each corner. The two columns are about 8 inches apart and the previous owners stuck a single pane of glass in the opening with stops on either side. I plan to get rid of the glass, add some blocking in between the columns and close the opening, insulating the gap, and using paneling on the inside to match the rest of the interior. On the outside I was going to sheath it with OSB, and then cover that with clear pine and paint it. I'm not sure what sort of weatherproofing I should add on top of the OSB. Should I just do tar paper, or house wrap and caulk all of the seams, before I put on the finish trim, or is there more I should do?
Thanks for any advice. I can supply photos if it would help.