Potential wall design feedback from professional
I will be building a house in climate zone 7B (dry) in Colorado at 9300 ft. I am wanting a “pretty good house.” average low temperature for Dec, Jan, Feb is -2F. Average high temperature for Dec, Jan, Feb is 35F. I have read Lstiburek’s book on building in cold climates and learned a great deal. Through my reading and google etc… I keep coming back to this design from outside to inside:
James hardie siding
1×4 rainscreen screwed with heco topix screws
3″ ComfortBoard (outtie triple pane vinyl windows using thermalbuck)
dorken delta vent s
1/2 plywood sheathing over 6″ studs 16″oc
2″ closed cell foam
fiberglass batt (flash and batt system)
I landed on the closed cell foam between the studs for two reasons. If I understand this correctly this will change the position of the first condensing surface to be on the sheetrock side of the foam. based on temperature of sheathing calculations in Lstiburek’s book this should keep me above the dew point “most” of the time. The second reason is I believe this would eliminate the requirement for an interior vapor barrier if I understand the code correctly?
I am not a builder, contractor, engineer etc… just a guy that can read a book and get a membership to GBA. Would some smart people that have experience give me their opinions of this design? If you need any other information that I left out please let me know.
Thanks in advance!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part