Tim Lange is taking on a major renovation of his 1910 home in North Dakota that will include a new roof, exterior spray-foam insulation, and new doors and windows. His quandary is what to do in the attic.
“I think I’ve got a good handle on the exterior insulation process — using window bucks to create an ‘outie’ style window is the current plan,” Lange writes in a Q&A post at GBA. “The third floor and attic are where I need some help.”
In the attic, Lange is dealing with three distinct zones: the area behind the kneewalls, the sloped ceiling in the living space, and the flat ceiling in the living space. He assumes the rafters are 2x6s on 2-foot centers. Judging from the photos he provides, none of it appears adequately insulated.
Lange is considering a number of possible approaches. “For the area behind the kneewall,” he writes, “one option would be to remove the fiberglass, add a layer of spray foam against the roof sheathing and finish with dense-packed cellulose to get the desired R-value,” he writes.
“I don’t see a way to effectively insulate the sloped section of the ceiling,” he continues. “There is just not enough room and it can’t be accessed easily. I suppose we could remove this part of the ceiling, fill the cavity with spray foam, then Sheetrock back over the foam. UGH. One suggestion was to dense-pack the area behind the kneewall and in the sloped ceiling area and pile lots of loose-fill in the main attic area. Not code-compliant, I know. But they do it out East.”
He could gut the third-floor attic to remove all the lathe and plaster, then spray-foam the underside of the sheathing to R-49 — that’s what’s recommended for his…