Trouble brewing mid retrofit in zone 6A
Energy efficiency remodel on 1953 ranch house. 2×4 studs, no vapor barrier. Half way started, then abandoned. 2 exterior walls untouched, the others were stripped, airsealed, R13 mineral wool between the studs, covered with Zip sheathing system, one wall had the incorrect eps installed before work ceased.
Exterior insulation and rainscreens are far from the norm here in western South Dakota. I hired the only local company that was willing to take this on. Unfortunately products were substituted, crew didnt understand how tape gets lapped, air sealing would have been skipped had I not been able to jump in as needed, multiple things built up until the company I hired quit, which I view as a fortunate thing. Attempting to rehire this company is not something I’m willing to do. This completely wrecks my goal of two 1″ layers of unfaced EPS with offset seams taped; topped with a furred out rainscreen.
I’m left with one company who would do metal siding with a layer of metal faced insulation of R3 but no thicker, which is not sufficient R value to guarentee safety from mold due to condensation on my sheathing, which makes this not a option for me.
Or a second company that would tear down to studs a second time, and install hubers Zip-R sheathing. Which I dont fully understand it’s possible issues.
I read a article on GBA.com about a North Dakota site but I didnt grasp it’s full understanding. I have R 13 in my 2×4 walls which means I need a minimum of R 7.5 exterior insulation to be assured of mold free sheathing issues. But Zip R has its insulation on the interior side of its sheathing, correct? What issues would I face if I went this route? If I dont do the Zip R then I am out of options for additional insulation. I dont have the ability or the friends to call on to do the insulation & rainscreen ourselves before paying a siding crew to finish it off. Would Zip R 9 be a viable option or not? Any additional concerns or points this raises?
Thank you GBA for being such a great resource to call upon.
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