Smart ways to fasten mineral wool and spend insulation budget
I have been trying to figure out the best way to spend my insulation budget on a new home I’ll be building this spring. I’m in climate zone 6A. It’s a 2 storey single.
For the enveloppe it will have 2×6 walls with batts, Blueskin vp100 as the WRB/air barrier, then either 1.5 or 2” or mineral wool followed by strapping and James Hardie lap siding.
When pricing out materials for the outsulation, it seems to jump from 1.5” to 2” mineral wool I would need to upgrade fasteners for the strapping from a fairly inexpensize (20 cents) 4” construction screw to something more like a 4.5” or 5” headlock screw which goes for about 80 cents each. Might not seem like much but it adds up to over $1000 for the entire project. Ironically the 2” roxul is actually cheaper around here than the 1.5”. Has anyone done any analysis to see if this $1000 would be better spent on something like blowing in another r30 or more into the attic instead of adding r2 to the walls? $1000 can buy a lot of cellulose. I do get there are limited returns after you reach a certain point.
Any thoughts or suggestions on this setup would be much appreciated!
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