This old house had a porch with storm windows that for years caused much agony. It leaked everytime it rained hard and required replacing wood and painting every few years.
A contractor was hired last year and replaced a lot of wood and installed replacement windows. The windows didn't have the extra piece like a new window, he did it like a replacement window. He felt the rotting wood was caused by a bad roof. The roofing, gutters and siding were replaced and the grading around the porch was changed. Today, the porch is air tight and covered with aluminum trim and there have been no leaks that I can see. But I noticed the caulking splitting here and there and the aluminum trim changed shape a bit. I've had to caulk after one year. I think there is a moisture problem.
I looked under the porch and found there was no insulation or vapor barrier. How much do you think the lack of a vapor barrier adds to this problem? If I were to add a barrier only, could I just attach it to bottom of the joists? Your prayers are always welcome.