My screened in porch inside roof gets mildewed during the winter. Does anyone know why? I'm considering converting to a 3-season but want to solve the mildew problem before thinking about adding a ceiling with or without insulation.
Not enough ventilation. You probably need vents at gable end, if it is a gable roof, or high on either side for a shed type roof. But if you will be closing it in, you should have soffit/ridge vents. Soffits are usually easy as are gable roofs, but shed roofs are harder. They do make a vent for adding to the top of a shed roof.
Thank you, Just Bill. I'm having a roofing contractor come out this week to look at putting in more ventilation. It is a gabled roof. I really appreciate your input. Planning to have a ceiling put in once it's ventilated and possibly insulate it, thinking it will keep the room cooler.