Jefferson County Climatic and Geographic Design Criteria for Garage Door Structural Specs

Jefferson County is one of the most geographically varied counties on the Front Range. Elevations range from under 5,500 feet near Wheat Ridge to over 11,000 feet in the mountains west of Conifer. Ground snow loads change dramatically with elevation. Jefferson County's design criteria reflect that variation.

What this source says

Jefferson County's Building Division publishes climatic and geographic design criteria for residential and commercial construction. The county's published criteria state:

Ground snow load shall be determined by address using the Jefferson County Climatic and Geographic Design Criteria lookup. Values are derived from the SEAC 2016 Colorado Design Snow Loads map and must be multiplied by 1.6 when used with ASCE 7-22 to determine the design ground snow load (pg).

Jefferson County's wind design criteria for most locations in the county are consistent with ASCE 7-22 and the 2025 Denver Residential Code:

• Ultimate design wind speed (Vult): 115 mph for most Front Range and foothills locations
• Wind exposure category: varies by site; Exposure B is common in residential areas with tree cover; Exposure C for open terrain
• Frost depth: 36 inches for most of the county

Elevation-dependent snow load. The county does not publish a single table of values. Instead, the building division directs applicants to look up the snow load for their specific address. This is because SEAC 2016 snow loads in Jefferson County range from about 25 psf at lower elevations near Denver to over 100 psf at higher mountain locations.

ASCE 7-22 conversion. Any project using the 2024 IBC or IRC (which Jefferson County has adopted) must apply the 1.6 conversion factor to SEAC 2016 values when using ASCE 7-22 for structural design.

When it applies

Residential garage projects in Jefferson County. Any building permit for a new garage, addition, or structural modification in Jefferson County requires the applicant to use the design criteria for their specific address. You cannot assume Denver's 43 psf applies to a Jefferson County address.

Garage header sizing. The structural header above a garage door opening must be designed for the actual roof snow load at the project site. For a home in Evergreen at 7,000 feet, the SEAC 2016 snow load might be 60 psf, producing a design ground snow load of 96 psf under ASCE 7-22 (60 × 1.6). The header required for that load is much larger than one designed for Denver.

Garage door wind rating. Jefferson County communities in the foothills may be in ASCE 7-22 Special Wind Region zones. For sites in exposed terrain, the Vult may be higher than 115 mph. Confirm with the building division whether a site-specific wind study is required before selecting a door.

Mountain community projects. Communities like Evergreen, Conifer, Bailey, and Idledale are in Jefferson County. Snow loads in those areas are far higher than the Denver urban core. A 16x7 garage door in Evergreen must be installed with a header designed for the local snow load, not Denver's 43 psf.

What this means for you

Look up your address before specifying. Jefferson County's design criteria address lookup at https://www.jeffco.us/2071/Climatic-Geographic-Design-Criteria gives the design values for your specific project location. Use those values, not a regional average.

Apply the 1.6 conversion factor. If the lookup gives you a SEAC 2016 ground snow load, multiply by 1.6 before using it in any ASCE 7-22 structural calculation.

Ask about exposure category. Exposure B and Exposure C produce different design pressures for the same wind speed. A home with a garage at the edge of a cleared lot faces higher wind pressure than one surrounded by trees. Confirm the correct exposure category with your engineer.

G Brothers serves Jefferson County from the Denver foothills to mountain communities and is familiar with the variation in snow loads across the county.

Full text and source

Jefferson County's climatic design criteria are at https://www.jeffco.us/2071/Climatic-Geographic-Design-Criteria. The SEAC 2016 Colorado Design Snow Loads map is at https://seacolorado.org/docs/2016-Colorado-Design-Snow-Loads.pdf.

Jefferson County design criteria apply only within Jefferson County. Neighboring unincorporated areas of Park, Clear Creek, and Gilpin Counties have different jurisdictions. Confirm the applicable code with the building department for any project near county lines.

Want to put numbers to this? Use the interactive roof snow load calculator below, or open the full roof snow load calculator with examples and notes.