Recommended R-values in zone 4
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
Unlimited depth — the cheapest R-value in the house
Walls
R-20
Minimum R-13
Capped by framing depth
Floors over unconditioned space
R-25
Minimum R-19
Matters most over vented crawl spaces
Crawl-space walls
R-15
Minimum R-10
For sealed, conditioned crawl spaces
Where zone 4 is
States whose most populous area falls in zone 4:
Representative cities: Washington, DC · Nashville, TN · Portland, OR · Kansas City, MO.
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 4
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
$2,600–$5,200
Includes a 1.00× 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
- Attic R-60 is the recommendation and is genuinely worth reaching here
- Vapor control starts to matter — avoid double vapor barriers
- Floors over unconditioned crawl spaces are worth insulating