Insulation advice please
I’m somewhat confused on the whole insulation issue. I’m working with an engineer on a 2,500 sq. ft. home in Truckee, Ca (Sierra Nevada, 6,000′ elevation, 210 lbs psf snow load: Wall construction will be 2×6 on 16″ centers. This is a cold climate:Zone 5, I think. Mostly dry in the summer, very little rain, precipitation mostly snow.
We are still in the planning stage. I want the house (my primary residence) to be well insulated: Walls R-24/R-25, Attic R-49, Sub-floor R-38 are my targets.
The more I read the more confused I get. Trying to get to the most cost-effective, proven solution. We have gotten prices on a couple of alternatives, one for $3,000 for R-21 in the wall cavity, the other for $6,000 for R-23 cellulose (JM Spider ?), again in the wall cavity. Is this the best use of $3,000 (going from R-21 batts to R-23 cellulose)? If not, what is the most cost-effective solution?
I also want the house to be air-tight, is spray-in-foam the only way to ensure the house is air-tight? Or should I look at air-tight drywall?
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