St. Clair County, MI Insulation Payback
St. Clair County, MI: what topping up your attic actually costs
St. Clair County sits in IECC climate zone 5 (Cold) — cold enough that heating, not cooling, is what decides the bill. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-60. Going from R-2 to the recommended R-60 costs roughly $3,480 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 1.8 years at an estimated $1,918/year saved. That's about as fast as attic paybacks get.
Heating vs. cooling in St. Clair County
The estimated savings split roughly $1,814/year heating, $104/year cooling. Out of every 100 US counties tracked here, St. Clair County's savings potential beats roughly 78 of them. Within zone 5 specifically, it ranks 125th of 745 counties by estimated savings. Michigan averages $2,064/year across the counties tracked here; St. Clair County comes in 7% lower.
Where these numbers come from
St. Clair County's climate figures — 6,785 heating and 649 cooling degree days a year — are read from RICHMOND 4 NNW, MI US, 7.3 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, St. Clair County sits at the 78th percentile nationally. St. Clair County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
The smaller top-up scenario
If St. Clair County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-49. That smaller top-up costs around $2,280 and saves an estimated $280/year — payback about 8.1 years. This one is a genuine toss-up, not a clear yes.
Getting it done in St. Clair County
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 St. Clair County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Nothing here is a guess
Every figure on this page traces to DOE/IECC climate zones and NOAA degree-day normals, documented in the methodology guide. The guide to what R-value actually means explains why R-60 is the target here specifically.