Recommended R-values in zone 3
These follow US Department of Energy and ENERGY STAR recommended levels for existing homes. Local building code may require more — check before you start.
Attic
R-60
Minimum R-49
Unlimited depth — the cheapest R-value in the house
Walls
R-20
Minimum R-13
Capped by framing depth
Floors over unconditioned space
R-19
Matters most over vented crawl spaces
Crawl-space walls
R-15
Minimum R-10
For sealed, conditioned crawl spaces
Where zone 3 is
States whose most populous area falls in zone 3:
Representative cities: Atlanta, GA · Dallas, TX · Los Angeles, CA · Charlotte, NC.
Several states span three or more zones — California, Texas, Nevada, Arizona, Oregon, Washington, New York, New Mexico, and Idaho among them. Altitude matters as much as latitude. If you are near a boundary,check the map or confirm with your building department.
What insulating costs in zone 3
A 1,240 sq ft attic taken from bare joists to R-60 with blown cellulose, in this zone:
DIY total
$930–$1,650
Material, air sealing, blower, safety gear
Professional
$2,450–$4,950
Includes a 0.95× regional labor adjustment
Material needed
69 bags
17.1" of cellulose
Generated by the same engine as the calculator. Our assumptions.
What matters in this climate
- Air sealing often returns more than extra attic depth in this zone
- Crawl spaces are common and frequently the weakest point in the envelope
- Wall insulation starts being worth the disruption at this latitude