Insulation requirements in Montana
Short answer
Montana spans climate zone 6. For most of the state (zone 6), the DOE recommends about R60 of attic insulation, with more in its colder areas.
Climate zones
6
Most of the state
Zone 6
Recommended R-values for Montana
Based on zone 6, which covers most of Montana. Colder parts of the state (higher zones) need more — enter your ZIP for your exact numbers.
| Area | Recommended R-value | Blown fiberglass |
|---|---|---|
| Attic / ceiling | R60 | 24.0" |
| Exterior walls | R20–R30 | 12.0" |
| Floors | R30 | 12.0" |
| Crawlspace / basement wall | R15–R19 | 7.6" |
Montanarebates & tax credits
The federal 25C tax credit (30% of insulation materials, up to $1,200/yr) applies everywhere. Montana's IRA rebate programs are administered by the state and rolling out on their own timeline. Check the official finder for Montana's current status and how to apply.
Find Montana's rebate programs →Last verified 2026-07-07.
Your exact numbers
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Frequently asked questions
How much insulation do I need in Montana?
Montana is in IECC climate zone 6. For most of the state the DOE recommends about R60 in the attic, with more in colder areas. Enter your ZIP for the exact zone.
Are there insulation rebates or tax credits in Montana?
Yes — the federal 25C tax credit covers 30% of insulation materials (up to $1,200/year), and Montana's IRA HOMES/HEAR rebate programs (up to $1,600 for insulation) are administered by the state. Check the official finder for current Montana status.
What climate zone is Montana in?
Montana is entirely in IECC climate zone 6.