You definitely will want some ventilation between your roof insulation and the bottom of the roof deck. As littel as 1" will be fine. The chutes or baffles can help with this. You also need soffit intake air vents to feed air to this area and some sort of other vents on the roof for exhaust. That said, with what you're doing, ventilation will be a challenge because of the hip roof.
Todd Miller
2011-06-04 06:57:18.000000
We had a metal, exposed fastener roof installed last fall. The contractor removed the one air vent. We have a 2 foot overhang but no soffit vents. The house is about 70 years old and drafty but we are going through(slowly) and gutting, re-wiring, and insulating, hoping to make it more air tight to keep more of the Minnesota wind and snow out! The attic floor is, well, FLOORED with planks. There is a small amount of insulation underneath, consisting of what seems to be sawdust encased in 2 sheets of tar paper. As we have gutted rooms below, we've replaced this with fiberglass batting with a kraft paper vapor barrier toward the room below. I'd like to make the attic into a craft room so I want to insulate the roof. What are my best options? Do I need vents? If so, how do I install them on a hip roof? Do I use chutes and fiberglass and put knee walls and a dropped ceiling in the center for air to move around? Do I need vents if we go the spray foam route? I'm concerned about moisture problems. I don't want to solve one problem while creating another! The rafters are only 2x4s with the hip and ridge rafters being slightly wider, perhaps 2x6.
I'd appreciate any advice I can get since I'd like to get this done soon in the hopes of keeping the house cooler this summer!
Thanks,
Darla
Darla Friesen
2011-05-31 17:30:24.000000
That room is going to be cold regardless.
If you were going to really try to make it comfortable, you are going to have to spend some money on spray foal (2lb closed cell) for the underside of the roof deck.
If you go the more traditional insulation route, I would install a vapour retarder on the otherside of the finished ceiling (drywall).
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