Zone 6B covers 119 counties in 7 states, home to about 2,394,682 people (FEMA NRI population). ENERGY STAR’s target for an uninsulated attic here is R60; with 3–4 inches already in place, add to R49.
Insulation targets for zone 6B
| Where | Guidance |
|---|
| Attic, uninsulated | R60 |
| Attic, 3–4 inches already | R49 |
| Floor over unheated space | R30 |
| Walls | When siding is removed: blow insulation into empty cavities and add R5 to R10 insulative sheathing; on an insulated 2x4 wall, add R10 sheathing. |
| Basement or crawlspace walls | Add R15 insulative wall sheathing or an R19 batt. |
Homeowner retrofit guidance, not your local code. Your jurisdiction may enforce an older or amended IECC; ask the building department before a permit job.
What it means for upkeep
Most zone 6B counties fall in the cold Building America region. Heating season dominates. Freeze protection, ice dams and furnace care are the big-ticket risks.
The “B” (dry) regime means low humidity, high sun and often hard water: sealants, roof coverings and water-using appliances wear faster.
See this month’s tasks for the cold region.
Largest counties in zone 6B
Yellowstone County, MT164,624Bonneville County, ID123,895Gallatin County, MT118,825Missoula County, MT117,719Flathead County, MT104,238Bannock County, ID86,991Cascade County, MT84,327Natrona County, WY79,870Lewis and Clark County, MT70,922Eagle County, CO55,552Madison County, ID52,900Bingham County, ID47,925Campbell County, WY47,000Bonner County, ID46,954Stevens County, WA46,368Ravalli County, MT44,109Summit County, UT42,322Fremont County, WY39,175Albany County, WY37,019Uintah County, UT35,592Silver Bow County, MT35,110Wasatch County, UT34,769Lake County, MT31,051Sheridan County, WY30,921Jefferson County, ID30,825Park County, WY29,572Blaine County, ID24,251Lincoln County, MT19,614Duchesne County, UT19,596Chaffee County, CO19,470Park County, MT17,153Alamosa County, CO16,357Hill County, MT16,298Carbon County, WY14,494Converse County, WY13,728Glacier County, MT13,712Archuleta County, CO13,356Pend Oreille County, WA13,347Fremont County, ID13,341Moffat County, CO13,270Mono County, CA13,147Big Horn County, MT13,034Sanders County, MT12,399Morgan County, UT12,295Boundary County, ID12,050Jefferson County, MT12,032Custer County, MT11,841Valley County, ID11,617Teton County, ID11,613Big Horn County, WY11,503Fergus County, MT11,438Roosevelt County, MT10,754Carbon County, MT10,455Deer Lodge County, MT9,414Beaverhead County, MT9,351Stillwater County, MT8,936 States in this zone: Montana (56), Idaho (22), Wyoming (17), Colorado (12), Utah (7), Washington (3), California (2).