Housewrap, foam board, vapor retarder
I know this topic may have been beaten to death, but I’m struggling finding a definitive answer to my questions.
I live in zone 5b (Colorado east of Rockies). I am replacing my old cedar siding and windows at the same time with Hardiplank. This house was built in the early 70’s. 2×4 construction, kraft-faced insulation. The exterior sheathing is about 3/4 fiberboard, in decent shape. It appears an R-5 is minimum for my area regarding rigid foam board. I had planned on using tyvek as well. I’ve read many papers at BuildingScience.com as well regarding this topic.
According to building science, the paper suggested that foil-faced boards weren’t recommended in cold climates, however I find many people using it in cold climates. I am keen of foil faced because of the reflectivity of the foil regarding radiant heat, higher R value (6.5) and higher compression strength. If I can use foil-faced, should I tape the seams if I use tyvek over it as the water plane? Should I even use tyvek? Should I use Tyvek with a xps board instead? I find a split preference of placing the tyvek on top of or beneath the foam board. The Tuff-R has a low permeability, and wonder how that would work in conjunction with housewrap.
At this point my wall would be: siding, Tyvek, foam board, fiberboard, 2×4, drywall.
We get very little rain, other than flash storms for 5 or so minutes at a time. Not sure if a rain screen wall is necessary?
So in summary, I’m stuck at order of wrap and foam, and type of foam.
Thanks for any guidance.
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