Quick background - We're trying to use greener options where we can
and were hoping to use cedar shakes for exterior siding. The
architect/builder helping us with design recommended using Zip R9
sheathing, which includes 1.5" polyiso and 7/16 Zip/OSB.
However,
Massachusetts code states in R703.6.1 "Wood shakes or shingles shall be
applied either single course or double course over nominal 1/2-inch
(12.7 mm) wood-based sheathing or to furring strips over 1/2-inch (12.7
mm) nominal nonwood sheathing . . . When installing shakes or shingles
over a nonpermeable water-resistive barrier, furring strips shall be
placed first vertically over the barrier and in addition, horizontal
furring strips shall be fastened to the vertical furring strips prior to
attaching the shakes or shingles to the horizontal furring strips."
So
the question is - do you interpret this to mean the only way to use the
Zip R9 is with furring strips OR does it mean we can't use cedar
shakes/shingles at all due to the 7/16 OSB?
That
lead us to look into Hardie shingles as an alternative, because there
is no minimum sheathing thickness requirement. However, they are 1/4"
thick and Mass code says 5/16 thick nominal for fiber cement siding . .
. Hardie lap siding is 5/16" but we initially weren't interested in
lap. So are the Hardie shingles a non-starter also?
That seems to push us to vinyl as an option or rethink the exterior insulation with Zip R.
Are we reading the code right and identifying the issues correctly?
Thanks for the help