Limited budget: Dense-packed cellulose or Zip R-3?
We are building a custom house in central Maryland, which is in Climate Zone 4 and has adopted the 2015 IECC.
Our budget is already stretched pretty far, so it looks like we can only afford one of these upgrades to our walls:
(1) Dense-pack cellulose insulation (instead of inexpensive fiberglass batts – exact R-value unknown)
(2) Zip R-3 (instead of regular Zip)
Which of these options would the Green Building Advisor Community recommend?
We are leaning toward the dense-pack cellulose for the slight increases in R-value, airtightness, and STC rating of the walls. The Zip R-3 would be a bigger boost to the R-value, but it wouldn’t have the other benefits.
A few other details:
– The wall assembly will be quite simple: HardiePlank siding, Zip sheathing, 2×6 studs + insulation, 1/2″ drywall, latex paint. A rain screen probably will not be included due to the extra cost it would incur, but we’ll have some pretty wide overhangs, which should mitigate this somewhat.
– We’ve asked about 24″ o.c. stud spacing, but it’s unclear if our builder has bought into that idea yet, so we might end up with 16″ o.c. studs.
– Our builder’s practice is to install interior strapping when using dense-pack cellulose to avoid concerns about bowing and fussiness with drywall installation (i.e., gluing drywall over stapled InsulWeb). This increases the cost of the dense-pack upgrade, but it seems they are unlikely to agree to install it any other way.
Thank you for any insight.
Joe in Maryland
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