Colorado

Statewide summary — confirm with your building department before designing

No value on this row was changed by this audit, but ground snow load and wind speed are not usable as single numbers. Ground snow load of 30 psf is essentially the Denver figure. The Pikes Peak Regional Building Department uses 43 psf below 7000 feet and 57 psf at or above it. Larimer County tabulates 55 psf at or below 5000 feet rising to 160 psf at 9000 feet and refers sites above 10000 feet to the Structural Engineers Association of Colorado snow load report; mountain resort communities design for several hundred psf. Wind speed of 120 mph is on the ASCE 7 ultimate scale, but the Front Range foothills are a designated special wind region and Larimer County states that minimum basic wind speeds vary between 115 and 225 mph depending on site, so a foothills lot needs a mapped value rather than this one. Seismic design category B is well supported: Denver, Colorado Springs, Grand Junction and Durango all compute to B for Site Class D and Risk Category II, and both Larimer County and the Pikes Peak Regional Building Department adopt B. Parts of northwest and southwest Colorado compute to C. Frost depth of 36 inches is a reasonable typical value; Larimer County adopts 30 inches countywide. Termite risk of slight corresponds to the compound slight to moderate band of the IRC map. SNOW LOAD AUDIT 2026-08-12 (physical design data pass). Minimum set to 30 psf. Maximum deliberately left NULL. Colorado was the hardest state in this pass and the reason is structural, not a research failure: read the paragraphs below before using either number. Colorado has no statewide building code. That is not an inference. The Office of the State Architect states it directly on its building codes page: Colorado has no statewide building code, and building codes are primarily adopted and enforced at the local level except where noted. The exceptions it lists are construction by state agencies on state-owned or state lease-purchased property, K-12 schools and health facilities under the Department of Public Safety, and manufactured homes, factory-built buildings, and hotels, motels and multi-family buildings in certain jurisdictions under the Division of Housing. The Colorado Energy Code is a genuine statewide mandate but it is an energy code and sets no structural load. There is exactly one Colorado state instrument that publishes a ground snow load, and this audit found and read it: 8 CCR 1302-14, the Division of Housing rules, current version effective 30 June 2026. Appendix A of that rule, the Colorado Regional Design Criteria Table, defines five snow load regions, SR-1 through SR-5. For each region it gives a strength-based ground snow load Pg in psf under three exposure models, full, partial and sheltered, at a thermal factor of 1.20. The values are SR-1 40, 36 and 30; SR-2 53, 48 and 40; SR-3 80, 72 and 60; SR-4 106, 96 and 80; SR-5 133, 120 and 100. The matching strength-based flat roof snow loads Pf are 30, 40, 60, 80 and 100 psf. The lowest ground snow load cell anywhere in that state table is 30 psf, and that is the minimum recorded on this row. The maximum is NULL rather than 133 because the state rule refuses to publish one. Above SR-5 the table gives a sixth designation, SSD, which the rule expands as Site-Specific Design. That is the mountain-West case-study answer in Colorado dress: the state declines to give a number for the high country. Colorado ski communities routinely design for several hundred psf. Publishing 133 psf as a Colorado maximum would be flatly wrong, and no state source supports any higher figure, so the cell is left empty. Three cautions attach to that 30 psf minimum. First, scope. Appendix A is written for factory-built structures approved by the Division of Housing and it says in its own header that it does not apply to HUD-code homes or to site-built hotels, motels and multi-family structures in areas of the state that do not have a building department. It does not govern ordinary site-built construction in a jurisdiction that runs its own building department, which is where most Colorado construction happens. Second, convention. The Appendix A Pg figures are explicitly strength-based, derived with the ASCE 7-22 flat roof snow load equation using the thermal and exposure factors printed in the table. They are not the allowable-stress ground snow loads that IRC Table R301.2 carried under earlier ASCE editions, and this audit did not convert between the two conventions in either direction. Third, ground versus roof. Rule 2.1.13, the Colorado amendment to IBC Section 1608.2, sets a floor of 30 psf on the ROOF snow load Pf for site-specific designs, and the older version of the same rule set the Division of Housing minimum as a 30 psf non-reducible roof snow load. The number 30 therefore appears in this rule as both a roof load floor and, coincidentally, as the lowest ground load cell. Only the ground figure is used here. On the Structural Engineers Association of Colorado report, which was the specific question this audit was asked to settle. Colorado Design Snow Loads, dated April 2016, published by SEAC, is the reference the Colorado design community actually uses. It is NOT adopted by any Colorado state instrument. 8 CCR 1302-14 was searched in full for it and neither the association nor the report is mentioned anywhere; the rule instead points designers to site-specific ASCE 7-22 values, or to local site data that the Division of Housing itself adopts and maintains, and requires a local jurisdiction demanding a higher load to show its site-specific case study before the Division will approve it. SEAC is a private professional association and the state publishes nothing equivalent. Colorado local jurisdictions do adopt the report by reference in their own ordinances and criteria, and two were confirmed: Larimer County directs that at elevations at or above 10,000 feet the ground snow load be taken from the SEAC snow loads report and map, and applies the April 2016 SEAC loads multiplied by 1.6 for IBC work; Gunnison County names the 2016 SEAC report as the primary reference for design ground snow loads in the unincorporated county. Because the adoption is local and not statewide, SEAC figures are recorded here as context and were not used to set the min or max. Effect on the four existing values. None were changed. Ground snow load 30 psf is retained but should be read as an allowable-stress Denver-area figure, not as anything the state publishes. Wind speed 120 mph is retained, with a caveat: the state rule has its own wind ladder, WR-1 through WR-5 at 115, 125, 140, 150 and 165 mph ultimate for Risk Category II at Exposure C plus a site-specific designation, and 120 mph appears nowhere in it; 115 mph is the Colorado state minimum, and it was not substituted because it is a floor rather than a statewide value and lowering the row would understate the Front Range foothills, which Larimer County describes as running between 115 and 225 mph. Seismic design category B is now confirmed against a Colorado state source for the first time: Appendix A sets a statewide minimum seismic design category of B, which agrees with the USGS-derived value recorded earlier. Frost depth 36 inches is retained; the state rule gives frost line depth as Per Local and publishes no number, and the Larimer County figure of 30 inches countywide recorded earlier was re-confirmed. Flagged for a future pass and not changed here because it is outside this audit's scope: Appendix A sets a statewide minimum termite damage probability of Moderate to Heavy, while this row stores slight.