Cathedral ceiling vs. standard ceiling: Insulation issues
I’m building a 20×20 detached garage with a finished loft area. Loft area will have 2 foot knee walls and a 14/12 roof pitch to maximize space where I won’t hit my head on the ceiling. I’m trying to decide whether the loft should just have a cathedral ceiling, or if I should add in framing for a standard 8′ ceiling.
From an insulation perspective, if I do a cathedral ceiling, should I just do an unvented roof and closed-cell spray foam insulation? I read the article on this webpage about unvented cathedral ceilings, and that seems to be the way to go. I’m in the Washington, DC area by the way — hot, humid summers and cold-ish winters, but only about 20″ of snow per year (maybe even less on average).
Other option is to go ahead and just have standard 8 foot ceilings framed into the loft, which would leave a small “attic” area above the ceiling. If I were to go that route, what would preferred insulation method be? Should I still just go ahead and do an unvented roof and do spray from on the entire roof? Or would I be better off doing a traditional vented roof, not insulate the roof itself, and just insulating the 8′ ceiling?
Any advice appreciated. Cost not particularly a concern. I just want to do whatever is going to be most reliable and last the longest.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part