Utah Energy Code
Utah Insulation Code for Salt Lake and Statewide (2026)
Utah's energy code changed on July 1, 2026. Here's what it now requires for homes in Salt Lake City, Salt Lake County, Utah County and across the state, and how permits filed under the old rules are handled.
What changed on July 1, 2026
Utah H.B. 65 (2026) replaced the residential energy chapter of the building code with a short, Utah-specific standard. Insulation minimums are now the same statewide, from Salt Lake County to St. George.
Current minimums
Permits applied for on or after July 1, 2026
| Building component | Minimum requirement |
|---|---|
| Above-grade walls | R-21 |
| Ceilings and roofs | R-38 |
| Floors over unconditioned space | R-30 |
| Conditioned basement walls | R-10 continuous or R-13 cavity |
| Windows and glass doors | U-0.32 maximum |
| Skylights | U-1.3 maximum |
| Opaque doors | U-0.6 |
Homes can also comply through REScheck at least 5% better than the Utah 2012 standard, or a HERS rating of 67 or better. The new table lists no separate slab-edge or crawl-space-wall values, so confirm with your plan reviewer how those are handled.
Air sealing and blower door testing
Maximum air leakage is 5.0 air changes per hour at 50 pascals (or 0.25 CFM per sq ft of enclosure) for single-family homes, and 6.0 (or 0.28) for multifamily. Instead of a test, builders can use the code's air-sealing checklist. Homes that test at 3 ACH50 or tighter need whole-house mechanical ventilation.
Ducts and mechanical rooms
Ducts outside the living space need R-8 insulation, and attic ducts must be leak-tested. Mechanical rooms that draw combustion air from outside must be insulated and air-sealed.
Climate zones still matter for roofs
Salt Lake, Utah, Davis and Weber counties are Climate Zone 5B; most of Washington County is 3B; high-elevation areas are 6B. The zone no longer changes residential insulation minimums, but unvented roofs still need closed-cell foam or rigid board on the cold side for condensation control: R-5 in Zone 3, R-20 in Zone 5 and R-25 in Zone 6.
Grandfathered permits
A project is judged by the code in effect when its permit application was accepted, not when insulation goes in. Salt Lake City applies the codes in effect on the date a plan submission is accepted for review, as long as fees are paid and the application hasn't lapsed. Applications and permits can lapse after 180 days without issuance or work, and a re-filed permit falls under the new code. Confirm with your building department.
Applications accepted July 1, 2024 – June 30, 2026
| Component | Zone 3B | Zone 5B | Zone 6B |
|---|---|---|---|
| Ceiling | R-38 | R-49 | R-49 |
| Walls | R-20 or R-13+5ci or R-15ci | R-21 or R-15+5ci or R-15ci | Same as 5B |
| Basement walls | R-13 or R-5ci | R-15 or R-11ci or R-11+5ci | R-19 or R-13ci or R-11+5ci |
| Crawl space walls | Same as basement | Same as basement | Same as basement |
| Slab edge | Not required | R-10, 2 ft | R-10, 4 ft |
| Floors | R-19 | R-30 | R-30 |
| Windows | U-0.32 | U-0.32 | U-0.32 |
| Air leakage | 4.0 ACH50 | 4.0 ACH50 | 4.0 ACH50 |
Commercial and larger multifamily
Commercial buildings and IBC multifamily projects follow the 2024 IECC commercial provisions with Utah amendments. Confirm the energy path with your design team before bidding.
Frequently asked questions
Ready to meet or exceed Utah code?
Hansen / All Seasons Insulation installs to code and beyond. Get a free estimate and we'll walk you through exactly what your home needs.
Summary for general information, not legal or engineering advice. The building official makes the final call. Sources: Utah H.B. 65 (2026); Utah Residential Energy Code Quick Guide; Salt Lake City Building Services. Updated September 2026.