ceiling-roof insulation 1880’s Vermont
Hello,
I live in Montpelier Vermont and am renovating a 1880’s house. the upstairs bedrooms have 3 regular walls and 1 that is the pitch of the roof. The pitched ceiling/roof starts about 2’6″ up from the floor and connects to the non-conditioned attic space. We recently removed the plaster (as it was cracking and falling away from the lath) from this section and see that the rafter -bays have been dense packed. In Martin Holladay’s book he specifically says this is done a lot in the Northeast and not correct. I am thinking of removing the dense pack and putting polyiso 2″ (cut and cobble method with spray foamed seams) then about 3.5″ of rockwool, then sheetrock. I know the R-value is going to under preform, however this section of wall/ceiling is only about 8’X8′ and I’m worried about $$$ & losing space in an already small room. Would anyone recommend a different approach? Also, curious to see the area is dry and seems to be preforming okay is that because the rafters connect up to the attic where there’s about 2′ of fluffy insulation?
Thanks for any help / ideas.
-Elden
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
When renovating your 1880s home with pitched ceilings, consider whether fully replacing the existing, functional dense-packed insulation is necessary. Your plan to use polyiso, rockwool, and spray foam is effective for sealing air leaks and enhancing insulation, but ensure it doesn't affect roof ventilation to avoid moisture problems. Since the affected area is small, consult a local expert to ensure your updates are cost-effective and meet local building standards. This focused approach will help optimize your renovation's impact and efficiency.