What R-value do I need in an attic in Minnesota?

Insulate attics in Minnesota to R-60, which is the practical target most utility rebates key off, even though the residential energy code sets R-49 as the minimum floor.

Minnesota spans Climate Zone 6 and 7, where winter design temperatures regularly drop below -10°F. Code is the legal minimum, not the comfort or rebate threshold. Most utilities in the upper Midwest structure their insulation rebates around R-60 for attic flats because that depth captures the diminishing-return sweet spot for heating cost reduction.

• Attic flat: R-60 target, about 16–18" of blown cellulose or 20" of fiberglass.
• Vaulted / cathedral ceiling: R-38 minimum with a continuous air barrier; R-49 is preferable.
• Walls, 2x6 framing: R-20 cavity plus R-5 continuous insulation, or R-21 cavity in existing framing.
• Rim joist: R-10 minimum, achieved with 2" of closed-cell spray foam.
• Air sealing first: an unsealed attic at R-60 performs closer to R-35 in a January wind.
• Rebate timing: most utility programs require pre-approval and a post-installation inspection, so apply before work starts.

The trade-off is thickness versus headroom and storage. R-60 in a flat attic is easy; in a shallow vaulted ceiling it can require furring or a hybrid foam approach. Chasing code minimums saves material but often leaves money on the table in rebates and heating bills.

Air-seal top plates, penetrations and chases first, then blow to depth and keep photos of the finished depth and baffles for the rebate inspector.