We’re building a home originally designed for Atlanta’s climates, but we’re in Central Pennsylvania. Plan has brick and cedar shingle siding and specs 2 x 6 exterior walls under shingled areas and 2 x 4 walls under brick. My builder and I have discussed using just Tyvek over the sheathing versus a layer of blue dow board to give us some extra insulation.
Your thoughts?
Replies
Chuck - Use a higher-R-value FG insulation like R-15C in the 2 x 4 walls and skip the foam. click here for FAQ's regarding Tyvek. Although Dow says it's OK, some folks feel that as a matter of practice it is NOT recommended behind brick veneer - use 30-lb felt. Note in the FAQ's that depending on exactly which product you use, minimum airspace requirements may apply. These may not always be achieved in standard residential construction.
T. Jeffery Clarke
Edited 4/23/2002 9:25:37 AM ET by Jeff Clarke
Thanks for your suggestions. By the way, what makes a 3 1/2 in layer of insulation R-15 instead of R13? It wasn't clear from the Owens Corning site.
Higher density fiberglas.T. Jeffery Clarke
Quidvis Recte Factum Quamvis Humile Praeclarum
It's not 3 1/2" thick, it's 3 5/8" inches thick.
Like Jeff said, it's also more dense, but not a whole lot more.
I've seen 100% cotton batts that are 3 1/2" and rated at R-19. BOY is it expensive though!James DuHamel
J & M Home Maintenance Service
"Southeast Texas"
Thanks, James & Jeff, I was a little worried about the standards--we've got one guy in the area building the foam block/concrete-filled homes (R=50?) up to the second floor. Waste of money? We don't have hurricanes here, so I think he just likes really big window sills.
Chuck.