Zone 5B covers 146 counties in 10 states, home to about 13,746,629 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 5B
| 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 5B 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 5B
Salt Lake County, UT1,185,141El Paso County, CO729,693Denver County, CO715,210Utah County, UT659,138Arapahoe County, CO654,201Jefferson County, CO582,825Spokane County, WA538,806Adams County, CO519,291Ada County, ID494,805Washoe County, NV486,264Davis County, UT362,649Larimer County, CO358,792Douglas County, CO357,700Boulder County, CO330,652Weld County, CO328,800Weber County, UT262,158Yakima County, WA256,420Canyon County, ID230,937Benton County, WA206,541Deschutes County, OR197,964Kootenai County, ID171,251Pueblo County, CO168,034Mesa County, CO155,647Santa Fe County, NM154,509Sandoval County, NM148,310Coconino County, AZ144,629Cache County, UT133,078San Juan County, NM121,421Navajo County, AZ106,501Nevada County, CA102,095Laramie County, WY100,483Grant County, WA98,978Franklin County, WA96,653Twin Falls County, ID89,972Umatilla County, OR79,888Chelan County, WA78,989Broomfield County, CO74,051Tooele County, UT72,600McKinley County, NM72,241Klamath County, OR69,248Apache County, AZ65,844Walla Walla County, WA62,555Garfield County, CO61,566Box Elder County, UT57,579Iron County, UT57,174La Plata County, CO55,533Elko County, NV53,581Fremont County, CO48,877Whitman County, WA47,922Kittitas County, WA44,271Siskiyou County, CA43,940Douglas County, WA42,903Montrose County, CO42,636Nez Perce County, ID42,062Okanogan County, WA42,016Rio Arriba County, NM40,200Latah County, ID39,513Taos County, NM34,371Lassen County, CA32,683Malheur County, OR31,546 States in this zone: Colorado (34), Idaho (22), Utah (21), Washington (18), Oregon (18), New Mexico (12), Nevada (9), California (6), Arizona (3), Wyoming (3).