Climate zone 4 insulation R-values

Short answer

In IECC climate zone 4, the DOE / ENERGY STAR recommendation is R60 in the attic, R20–R30 in exterior walls, and R25–R30 in floors over unconditioned space.

Recommended R-values (zone 4)

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"

U.S. DOE / ENERGY STAR recommended levels (2021 IECC). Thickness shown for blown-in fiberglass; the calculator converts to eight other materials.

Your exact zone

Climate zone 4 covers many counties across several states. Enter your ZIP to confirm your exact zone and get material thicknesses, cost, and savings for your home.

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Other zones

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Frequently asked questions

What R-value insulation do I need in climate zone 4?

In IECC zone 4, aim for R60 in the attic and R20–R30 in exterior walls, following the DOE / ENERGY STAR recommended levels for the 2021 IECC.

How much attic insulation is recommended for zone 4?

About R60 for the attic in zone 4. Blown-in fiberglass or cellulose is the usual choice — enter your ZIP in the calculator to see the exact inches for each material.

Is upgrading attic insulation worth it in zone 4?

Topping a 1,000 sq ft attic from ~R11 up to R60 saves an estimated $150/year on heating in zone 4, and may qualify for a 30% federal tax credit on materials.