Cedar Breather under metal roofing?
Hello helpful people,
We have been mulling over our unvented vaulted roof assembly and wondered if using cedar breather is redundant. The assembly is Huber Zip sheathing, three inches of polyiso above deck, 2″ wide furring made from ripped Avantech spaced 12″ apart over the foam and a metal standing seam roof. Do we need cedar breather between the metal roof and furring as well or will there be sufficient circulation between the furring strips to prevent issues with condensation? We are aware of the 40/60 insulation above and below deck recommendation for this kind of roof assembly and have planned accordingly.
This is a home in Virginia.
Thank you!
Lisa and Paul
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Lisa and Paul,
You don't need Cedar Breather under the metal roofing.
Note that building codes require the installation of roofing underlayment (for example, asphalt felt or one of the new synthetic roofing underlayments) under your metal roofing. In your case, the roofing underlayment would be installed between the top of the rigid foam and the furring strips.
For more information, see these two articles:
"How to Install Rigid Foam On Top of Roof Sheathing"
"Combining Exterior Rigid Foam With Fluffy Insulation"