u/John--Henry — reddlx

I am building a screened in porch and this spring noticed condensation on the underside of the roof decking. The roof is a standing seam metal roof, underlayment, sheathing. The condensation only happened for a few days when there was still snow on the roof but the weather was unseasonably warm and humid. There are no soffit vents and no ridge vent. I was hoping to put up a ceiling on the underside of the rafters but don't want to trap moisture. The only solution that I can come up with is to glue rigid foam board between the rafters and seal the edges but I'm not sure if this will work or just cause different problems if a ceiling is installed below it.