General Exterior Code Requirements in Utah

Seismic liquefaction potential exists in portions of Salt Lake Valley (especially near the Jordan River and Great Salt Lake margins), Utah Valley (near Utah Lake and Provo River), and Weber/Davis county lowlands. These areas have shallow groundwater and unconsolidated sandy/silty sediments susceptible to liquefaction during seismic events. Utah Geological Survey has mapped liquefaction potential along the Wasatch Front.

Several Utah counties fall within EPA Radon Zone 1, including Salt Lake, Utah, Davis, Summit, and Wasatch counties along the Wasatch Front. Granitic bedrock and uranium-bearing formations in the Colorado Plateau contribute to elevated radon levels. IRC R324 radon-resistant new construction is recommended. The Utah Department of Environmental Quality tracks radon testing data by county.

Utah mountain areas experience ground snow loads from 50 to over 200 psf, particularly in the Wasatch Range, Uinta Mountains, and Bear River Range. Park City, Brighton, and Alta areas have among the highest snow loads in the state. Roof design per ASCE 7-22 Chapter 7 is critical. Utah jurisdictions use locally adopted snow load maps that may exceed ASCE 7 values for site-specific conditions.

Utah counties in IECC Climate Zones 5B through 7 require ice barrier underlayment at eaves per IRC R905.1.2. This includes the Wasatch Front, Park City, Bear Lake area, and all mountain communities above 5,500 feet elevation. Ice dams are common in Utah due to high snowfall combined with solar gain on south-facing roofs.

Northern Utah and mountain communities experience frost depths of 30 to 48 inches. Cache Valley (Logan area) and the Uinta Basin have the deepest frost penetration in the state. Foundation footings must extend below the local frost line per IRC R403.1.4. Utah jurisdictions typically require 30-36 inch minimum footing depth along the Wasatch Front.

Utah has significant historic districts including Temple Square and The Avenues (Salt Lake City), 25th Street (Ogden), Main Street (Park City), and numerous mining-era towns. Restoration work in these districts requires compliance with local historic preservation ordinances and may need Utah State Historic Preservation Office review. Secretary of Interior Standards apply for National Register properties.

Central and eastern Utah contain limestone and gypsum formations susceptible to dissolution and karst development. The Wasatch Plateau, Fishlake area, and portions of the Colorado Plateau have documented sinkholes and caves. Geotechnical investigation per IBC 1803 is required where karst features are present. Gypsum karst is particularly hazardous due to rapid dissolution rates.

Utah has Zone AE designations along the Jordan River, Weber River, Provo River, and Great Salt Lake shoreline. Spring snowmelt runoff drives annual flood risk. The 1983-84 Great Salt Lake rise caused hundreds of millions in damage. Alluvial fan flooding in mountain valleys is a distinct hazard. NFIP requirements apply per 44 CFR 60.3.

The Wasatch Fault is the longest and most active normal fault in North America, extending approximately 240 miles from southern Idaho to central Utah. The Wasatch Front corridor (Ogden-Salt Lake City-Provo) is classified as Seismic Design Category D, the highest seismic risk in the Intermountain West. Affects Salt Lake County, Utah County, Davis County, Weber County, and Cache County. The fault is capable of producing M7.0+ earthquakes with recurrence intervals of approximately 300-400 years on individual segments.

Widespread expansive soils (bentonite/montmorillonite clay) found in Washington County (St. George area - most severe), Utah County (portions), Salt Lake Valley (western portions), Iron County (Cedar City area), and areas underlain by Mancos Shale formation in central and eastern Utah. Expansion indices can exceed 130 (severely expansive). Expansive soils are the #1 geotechnical hazard for residential construction in southern Utah.

Areas designated as Zone A, AE, or AH on FEMA Flood Insurance Rate Maps. Utah flood risk includes: Jordan River corridor through Salt Lake Valley, Provo River and Utah Lake area, Weber River corridor, Virgin River in Washington County, and numerous mountain canyon drainages subject to flash flooding and debris flows. Spring snowmelt runoff causes seasonal flooding risk along Wasatch Front. Utah experienced major flooding in 1983-84 from Great Salt Lake rise and in 2023 from record snowpack.

Mountain interface areas along the Wasatch Range (east bench of Salt Lake Valley, Draper, Alpine, Highland, Cedar Hills, Provo east side), Summit County (Park City, Snyderville Basin), Wasatch County (Heber Valley east side), Cache County (Logan Canyon), and southern Utah mountain communities. Utah has experienced destructive WUI fires including the 2012 Dump Fire (Saratoga Springs) and numerous foothill fires along the Wasatch Front. Drought conditions exacerbate risk.