Denver DRC Table R301.2(1) - Climatic and Geographic Design Criteria for Garage Door Specs

Every garage door sold in Denver needs to meet specific structural performance ratings. The numbers that drive those ratings come from one table in the Denver Residential Code: Table R301.2(1). The 2025 Denver Building Code, effective December 31, 2025, updated two of those values from the previous code cycle.

What this source says

The 2025 Denver Residential Code (based on the 2024 IRC with Denver amendments) establishes these design criteria for all residential construction in the City and County of Denver:

Ground snow load: 43 psf Ultimate design wind speed (Vult): 115 mph Wind exposure category: C Frost depth: 36 inches Seismic Design Category (SDC): B

The biggest change from the 2022 DBC is the ground snow load increase from 35 psf to 43 psf. Denver CPD adopted this based on ASCE 7-22 conversion factors and updated Front Range weather data. The 2025 codes took effect June 13, 2025. Projects with drawings submitted after December 31, 2025 must use the new values.

Exposure C means Denver sits in relatively open terrain with few large windbreaks at the city edge. Exposure C produces higher design pressures than Exposure B (wooded or suburban terrain). This means door wind ratings need to be higher than the mph number alone suggests.

When it applies

These values drive structural decisions at every stage of a garage door project:

Door wind rating (Vult 115 mph, Exposure C): Under ANSI/DASMA 108 and IRC R609.4, a sectional door must be tested to resist the design pressure for your location. For a 16x7 door in Denver's Exposure C at 115 mph Vult, the required design pressure is about 20-22 psf. Check the door's permanent wind label (required by IRC R609.4.1) to confirm its rated pressure is at or above that number.

Snow load on a garage roof (43 psf ground): For attached garages or garages under a living space, an engineer converts ground snow load to roof snow load using ASCE 7-22 Chapter 7. The jump from 35 to 43 psf changes that math and may affect header sizing above the door. If you are adding a room above an existing Denver garage, the structural design must use 43 psf.

Frost depth (36 inches): Track anchors and slab edges in unheated garages can shift from frost heave. Any footing or anchor that relies on ground bearing must go below 36 inches to stay stable year-round.

Seismic Design Category B: SDC B is relatively low seismic exposure for garage door purposes. Standard residential hardware meets SDC B requirements without special detailing.

What this means for you

Replacing a door in Denver: the new door must carry a wind label showing it was tested at 115 mph Exposure C or higher. Most doors rated for 130 mph cover Denver comfortably. Doors rated only for Exposure B at 115 mph may fall short.

New attached garage or permitted replacement: your contractor and structural engineer use 43 psf ground snow load (not the older 35 psf) for the header and beams above the door. If you have a structural plan from 2024 or earlier, confirm it used 43 psf before submitting for a 2025-code permit.

Littleton, Englewood, Aurora, or Lakewood: each city publishes its own Table R301.2(1). Denver's 43 psf does not apply to them automatically. Check the specific jurisdiction.

G Brothers quotes doors with wind and structural ratings appropriate for the Denver design values and can provide documentation for permit submittals.

Full text and source

The 2025 Denver Building and Fire Codes are published by Denver Community Planning and Development at https://www.denvergov.org/Government/Agencies-Departments-Offices/Agencies-Departments-Offices-Directory/Community-Planning-and-Development/Building-Codes-Policies-and-Guides.

This entry reflects the 2025 Denver Residential Code, adopted June 13, 2025, with full compliance required after December 31, 2025. Projects permitted under the 2022 DBC used a 35 psf ground snow load. Evaluate those projects against the code that was in effect at the time of permit.

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.