COLORADO · DENVER · ASCE 7-22
Where the Front Range throws its wind a mile above the sea
Denver County design wind loads, shaped by chinook downslope blasts off the Rockies and the thin air of the Mile High City.
FRONT RANGE PROFILE
Air that spills down the divide
Westerly flow crests the Continental Divide, plunges the eastern slope, and accelerates through compression onto the city below.
Compression and adiabatic warming turn that descent into the warm, dry chinook — the “snow eater” that can hold gusts past 100 mph for hours.
CHINOOK & THIN AIR
Two forces only Denver has to balance
A high non-coastal base speed pushing loads up, and a mile of altitude thinning the air back down.
Snow-Eater Gusts
Sustained 60-80 mph chinooks with gusts topping 100-140 mph load roofs and cladding for hours, not seconds.
DOWNSLOPE WINDMile-High Ke
At ~5,280 ft the air is roughly 17% thinner, so the ground elevation factor Ke trims velocity pressure toward 0.85.
GROUND ELEVATIONCore vs Open Plains
Dense neighborhoods read Exposure B; the eastern fetch toward the plains opens projects up to Exposure C.
EXPOSURE B / CFoothills Topography
Lakewood, Golden and Morrison sit on slopes and escarpments that push the topographic factor Kzt above 1.0 near the crest.
Kzt > 1.0Net effect: Ke softens the pressure for altitude, but Denver’s high non-coastal base speed more than makes it back — design pressures stay heavy across the Front Range.
READING THE MAP
How occupancy moves Denver’s speed
Higher risk category means a longer return-period map — a different V you read for the same Denver address.
| Risk Category | Denver Design Speed | Who It Covers |
|---|---|---|
| Category I | ~110-120 mph | Minor ag, storage and temporary structures |
| Category II | 115-130 mph | Homes, retail and most standard occupancies |
| Category III | ~130-145 mph | Schools, large assembly, hazardous-material sites |
| Category IV | ~140-155 mph | Hospitals, fire stations, shelters and EOCs |
No fixed importance multiplier applies in ASCE 7-22 — the category selects which speed map you read.
PERMIT PATHWAY
Clearing a Denver CPD wind review
What the home-rule city and county expects on the way to a sealed Front Range permit.
Home-Rule Code
The consolidated City and County of Denver adopts the IBC with Colorado and local amendments.
IBC + CO + DENVERCurrent Standard
Wind calculations follow ASCE 7-22 as referenced by Denver’s adopted IBC edition.
ASCE 7-22PE Seal
Commercial and multi-family designs need a Colorado-licensed PE; engineered residential is strongly advised.
CO LICENSEWind-Snow Pairing
Combine the 25-40 psf ground snow load with wind for roof drift and unbalanced cases.
LOAD COMBOSTopographic Check
Foothills sites add a Kzt adjustment for slope and escarpment near the crest.
KztCPD Submittal
File MWFRS and C&C pressures with Denver Community Planning and Development.
DENVER CPDAROUND THE DIVIDE
Carry the work across Colorado
From the Denver metro out to the statewide picture and the wider map.
MILE-HIGH READY
Settle Denver’s loads in one pass
Address in, chinook speed, elevation Ke, exposure and foothills Kzt out — with a PE-ready report for CPD.