I added a 3 seasons porch to my existing cottage, but now like it so much I'd like to have year round use. Porch is 8' deep, 32' long, 7:12 pitch open ceiling with 2x6 rafters (16" on center)...connected to anchor on house. Porch just has storm windows on it. I added wiring for 2 6' baseboard heaters. Floors and walls are insulated and finished. How do I insulate in the rafters so there's proper air flow/venting. Is it possible? There is a 1' overhang of end of porch roof.