Plymouth County, MA Insulation Payback
Attic insulation payback for Plymouth County, MA
Plymouth County, Massachusetts is zone 5 under DOE's climate map (Cold), which means winters that dominate the energy bill, with cooling a minor factor. An uninsulated attic there should be built up to R-60. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-60 runs an estimated $3,480, and saves about $1,549 a year in heating and cooling — a payback around 2.2 years. Hard to find a home improvement with a faster payback than this.
The breakdown behind the number
Of that, about $1,420/year comes from reduced heating and $129/year from reduced cooling load through the ceiling. Plymouth County beats 56% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 745 counties DOE places in zone 5, Plymouth County ranks 695th. Against Massachusetts's own average of $1,728/year, Plymouth County runs 10% below that.
The climate data behind this
NOAA's PLYMOUTH-KINGSTON, MA US station, 2.4 miles from Plymouth County, supplies the 5,309 HDD and 805 CDD this estimate runs on. That combined heating-and-cooling load ranks Plymouth County 1446th nationally by total degree days — the 54th percentile. DOE also classifies Plymouth County as moisture regime A (humid) - ask a local contractor whether that changes the vapor-barrier approach for this job.
The smaller top-up scenario
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $226/year saved — roughly 10.1 years to break even. It is close - the payback only just fits a reasonable timeframe.
Quotes and materials for this job
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $3,480 as a starting estimate for a Plymouth County job, not a quote. Expect at least a $600 minimum charge from most contractors.
More on how this was built
Nothing here is a guess: the methodology guide names the DOE climate map and NOAA station data behind every number on this page. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.