How to insulate a cathedral ceiling from within the rafter bays
I have a zone 7 1840s house-and-a-half style house, with the second floor walls going about 4 ft up, then sloped cathedral ceiling for another 3 ft up, capped by the flat ceiling and a 4′ high crawl space attic. Essentially the second floor looks like a rectangle with the upper corners knocked off, and every surface but the top and bottom is exterior facing. So the sloped ceilings are the thickness of the lathe and plaster, the rafters, and the roof.
目前我有纤维素(许多年吹ag)o), and not enough of it. Not entirely sure if i have vent baffles put in or not, nor what they might be made of if they are in, but either way there are no soffit vents anyway so i doubt they do much good. The roof itself is relatively new and in very good shape, so i don’t want to remove it. The ceiling was re-plastered a few years ago and i would also not like to remove it.
Is there a way to insulate this structure to code, or even kind of close to code, without tearing off one or the other? Ideally i would like to have all the cellulose removed, put vent baffles in (and put soffits into the eaves so they go somewhere), and fill the gap between the lathe and the baffle with closed cell foam, and fill the rest of the flat areas with blown in cellulose (new, non-mouse-dropping filled stuff). I’ve been told by a local insulation company that they wouldn’t be able to put in the foam by shoving the applicator down the rafter bays and filling it from the bottom up because it wouldn’t cure properly.
Is this correct, and if so does anyone have any other ideas? It would be nice to have the proper amount of insulation for a change, but tearing off all the ceiling surfaces in the entire house and starting over from scratch is a hassle i don’t need.
Thanks!
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Replies
Terry,
Q. "Is there a way to insulate this structure to code, or even kind of close to code, without tearing off one or the other [the roofing or the ceiling]?"
A. No. For more information, seeInsulating a Cape Cod House.
-- Martin Holladay
I suppose its close to a cape cod house, but i don't have the lower triangular knee walls - the roof actually ends halfway up. But fair enough - half of the cape cod problems are the same.
Supposing i do try ripping down ceilings. The insulation guys said that i would probably be running into stack effect problems if i only did one part at a time. One half of the house is the original and the other half is the addition (circa 1900), and they are quite separated (only one doorway on the upper level between the two). I was thinking that eventually i need to do some work on the addition section anyway, so i could get that half of the house insulated properly. Will that cause me more trouble than its worth?
Terry,
Q. "The insulation guys said that i would probably be running into stack effect problems if i only did one part at a time."
A. I disagree with your insulation guys. Your house may well have stack effect problems now -- most houses do -- but addressing these stack effect problems by performing air sealing work and improving insulation details, even in just half your house, won't make things worse.
Q. "I was thinking that eventually i need to do some work on the addition section anyway, so I could get that half of the house insulated properly. Will that cause me more trouble than it's worth?"
A. No. Go ahead and do half the house now.
-- Martin Holladay
Awesome. thanks!