Recommendations for insulating existing space over garage with a cathedral ceiling
I live in Massachusetts (Zone 5A) and have some space over the garage that I would like to finish as an office. The space has a sloped roof with 2x8 rafters, with soffit vents and a ridge vent (but no existing insulation). I'll be adding some 5 foot kneewalls and a ceiling, leaving about 4-5 feet of cathedral ceiling between the two.
What are my options for insulating the space? I have looked at closed cell insulation but quotes have come in at about $5-6K to insulate the entire roof deck (no venting). So I'm looking for cheaper alternatives.
I am thinking this (outside in):
Roof deck | 1" vent " | Fiberglass Batt | 2" Rigid foam insulation | Drywall
Where should the vapor barrier go? Should I use faced batts or something else (either between the fiberglass and rigid foam or on top of rigid foam?)
Which rigid foam would would I use? XPS or polyiso?
Posted Fri, 10/04/2013 - 09:02
Edited Fri, 10/04/2013 - 09:34
Other Questions in Energy efficiency and durability