Recommended R-values in zone 7
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-21
Minimum R-13
Capped by framing depth
Floors over unconditioned space
R-38
Minimum R-30
Matters most over vented crawl spaces
Crawl-space walls
R-19
For sealed, conditioned crawl spaces
Where zone 7 is
States whose most populous area falls in zone 7:
Representative cities: Duluth, MN · Fargo, ND · Fairbanks, AK · International Falls, MN.
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 7
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
$3,000–$6,000
Includes a 1.15× 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
- Exceeding the recommended R-60 can be justified here, unlike most zones
- Continuous exterior insulation on walls is worth the cost
- Moisture management is critical — warm interior air meeting cold surfaces condenses