Insulation requirements in District of Columbia
Short answer
District of Columbia spans climate zone 4. For most of the state (zone 4), the DOE recommends about R60 of attic insulation, with more in its colder areas.
Climate zones
4
Most of the state
Zone 4
Recommended R-values for District of Columbia
Based on zone 4, which covers most of District of Columbia. 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 | R25–R30 | 12.0" |
| Crawlspace / basement wall | R10 | 4.0" |
District of Columbiarebates & tax credits
The federal 25C tax credit (30% of insulation materials, up to $1,200/yr) applies everywhere. District of Columbia's IRA rebate programs are administered by the state and rolling out on their own timeline. Check the official finder for District of Columbia's current status and how to apply.
Find District of Columbia's rebate programs →Last verified 2026-07-07.
Your exact numbers
Enter your ZIP codeOther states
Frequently asked questions
How much insulation do I need in District of Columbia?
District of Columbia is in IECC climate zone 4. 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 District of Columbia?
Yes — the federal 25C tax credit covers 30% of insulation materials (up to $1,200/year), and District of Columbia's IRA HOMES/HEAR rebate programs (up to $1,600 for insulation) are administered by the state. Check the official finder for current District of Columbia status.
What climate zone is District of Columbia in?
District of Columbia is entirely in IECC climate zone 4.