Extra insulation costs reasonable?
We are planning to build a new home in climate zone 4A (DC metro area), and I’m wondering about the best place to invest funds for more insulation.
The builder includes this insulation:
Ceiling R-Value: 38
Wood Frame Wall R-Value: 15
Floor R-Value: 19
Basement Wall R-value: 10 (continuous insulation)
Basement Wall R-Value: 13 (cavity insulation)
Slab R-value: 10, 2 ft
And there are some more options that we are considering:
Closed cell spray foam, 0.5 inch thick, in the wall cavities, in additional to the standard batt insulation (hybrid? They already use some spray foam between floors, behind switches/outlets, but this adds to walls): $5500
Change attic insulation to R-49, (and change roof trusses): $1500
Change first and second floor walls to 2×6 with R-21 insulation: $5500
Add R10 rigid foam insulation under basement slab: $4900
The builder has been emphasizing that they create really efficient homes already (HERS rating of 58?), but it seems like during build time is the best time to put in more insulation.
Apologies if I asked something stupid. All of this is pretty new to me. Where would you spend money? Especially to get the biggest bang for your buck? Or are all of these additions overkill? We are hoping to keep utility costs down, with a comfortable home.
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