Jason Shapiro took the plunge and invested in more insulation for his house: blown cellulose for his attic and dense-packed cellulose in the exterior walls. No doubt he’d like to be enjoying a warmer house and lower energy bills. Instead, he’s dealing with a mess.
“We have now had significant snowfall and freezing rain, and today I noticed a leak from the top of a window casing in the wall that was dense-packed,” Shapiro writes in a Q&A post at GreenBuildingAdvisor. “When I went up on a ladder to look at the gutter, I found a significant amount of frozen cellulose protruding from a gap between the slate roof tiles and the sheathing underneath.”
It looks like the cellulose was wicking up moisture from the outside and allowing it to get into the wall, but why is the excess cellulose there in the first place? Shapiro says foam insulation baffles were placed between each rafter before the cellulose was blown in, and the top plate was sealed with spray foam.
“The soffits appear to be filled with cellulose that is poking out through the vents, and which can be easily seen from the outside of the house,” Shapiro says. “I am also able to reach up through and behind the gutter and under the sheathing and can feel a large amount of wet cellulose. The contractor is saying that there must have been a problem with the roof that allowed the cellulose to communicate to the exterior in this way. He is also saying that there is no need to remove the wet cellulose because it is treated with borate and will not mold.”
Source of the problem
GBA senior editor Martin Holladay points to one potential cause:…