# Insulating Attic - Peaked Roof addition over Built-Up Roof



## Gary in WA (Mar 11, 2009)

Welcome to the forum!

"Now for insulating this space... can I assume that the built-up roof will provide a decent vapor retarder? Then I could just fill above it with blown in insulation. I would still have to add some insulation in the cavity at the outside wall." --- It will stop moisture unless there is air getting under the flat roof, which it sounds like. The insulation on stops heat when close to the source. Any air space is counter-productive; http://www.diychatroom.com/f98/biggest-loser-fiberglass-insulation-90438/

"Or... fill the cavity between drywall and built-up with closed cell foam. Leave old paper backed batt in there? " --- Would only work if the ends are air tight.

"Or... remove drywall, old batt, put in new batt, new poly vapor barrier then new drywall." ---- Doubt you could get the 16" required in the old roof, though could add insulation above old roof also. Don't like the two v.b. idea for condensation for sure because old roof is impermeable.

Gary


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