Insulation R-Value Guide: What Your House Actually Needs in 2026

IECC 2024 minimums (residential)

These are the codes most states adopted for 2026 permits:

• Zone 1–2 (FL, TX Gulf, LA): attic R-38, walls R-13
• Zone 3 (most Southeast): attic R-49, walls R-20
• Zone 4 (VA, KY, TN, NC, CA coast): attic R-60, walls R-20
• Zone 5 (Midwest, PA, NY, MA): attic R-60, walls R-20 + R-5 continuous
• Zone 6–7 (northern MN, ND, ME, AK): attic R-60, walls R-20 + R-10 continuous

Where extra R-value pays back

Attic insulation is the single best dollar you can spend on an existing home — payback under 5 years in zones 4+. Wall insulation retrofits rarely pay back before 15 years unless you're already opening walls.