No Mandatory Wind Load Permit Required
Colorado is one of 40 states where building departments do NOT require wind load calculations by law to obtain a building permit. However, you may still need wind load calculations for insurance requirements, manufacturer warranties, liability protection, or engineering best practices.
Colorado Code Adoption - Home Rule State
Colorado is a home rule state, meaning building codes are adopted at the local jurisdiction level rather than statewide. Each city, county, and municipality determines which edition of the International Building Code (IBC) and associated standards to adopt.
Important: Always Verify Local Requirements
Because Colorado lacks statewide code adoption, you must verify the adopted code edition with the local building department before beginning any project. Code editions can vary significantly between neighboring jurisdictions.
Key Jurisdiction Code Adoption
Aurora
Current Code: 2021 IBC
Wind Standard: ASCE 7-16
Updated: April 2023
ASCE 7-16Denver
Current Code: 2021 IBC
Transitioning to: 2024 IBC / ASCE 7-22
Effective: December 31, 2025
ASCE 7-16 ASCE 7-22 Dec 2025Colorado Springs
Current Code: 2021 IBC
Wind Standard: ASCE 7-16
Status: Verify locally
ASCE 7-16Boulder
Current Code: 2021 IBC
Wind Standard: ASCE 7-16
Status: Verify locally
ASCE 7-16Aurora Engineering Design Criteria
The City of Aurora provides specific engineering design criteria that apply to wind load calculations:
| Parameter | Value |
|---|---|
| Ground Snow Load (Pg) | 40 psf |
| Basic Wind Speed (Risk Cat II) | 105-110 mph |
| Basic Wind Speed (Risk Cat III) | 110-115 mph |
| Basic Wind Speed (Risk Cat IV) | 120-125 mph |
| Default Exposure Category | B |
| Weathering | Severe |
| Minimum Frost Depth | 36 inches |
| Winter Design Temperature | 1°F |
| Ice Barrier Underlayment | Required |
| Mean Annual Temperature | 50°F |
Ground Elevation Factor (Ke) - Critical for Colorado
Why Ke Matters in Colorado
ASCE 7-16 introduced the Ground Elevation Factor (Ke) which adjusts velocity pressure for reduced air density at higher elevations. This is critical for Colorado projects where elevations range from 3,500 ft to over 14,000 ft.
At higher elevations, air density is lower, which reduces the force that wind exerts on structures. The Ke factor accounts for this physics-based reduction in wind pressure.
| Elevation | Ke Factor | Pressure Reduction |
|---|---|---|
| Sea Level | 1.00 | 0% |
| 3,000 ft | 0.94 | 6% |
| 5,280 ft (Denver) | 0.88 | 12% |
| 6,000 ft | 0.86 | 14% |
| 8,000 ft | 0.82 | 18% |
| 10,000 ft | 0.78 | 22% |
ASCE 7-16 Velocity Pressure Formula
Denver Example (5,280 ft)
At Denver's "Mile High" elevation, Ke = 0.88 approximately. This results in a ~12% reduction in design wind pressures compared to an identical building at sea level. This can significantly impact product selection and structural design.
Denver's Transition to ASCE 7-22
The City and County of Denver is adopting the 2025 Denver Building Code based on the 2024 International Building Code series, which references ASCE 7-22 for wind loads.
Key Dates
July - December 2025: 6-month transition period
December 31, 2025: Full adoption effective date
2024 IBC Code Package
- 2024 International Building Code (IBC)
- 2024 International Energy Conservation Code (IECC)
- 2024 International Fuel Gas Code (IFGC)
- 2024 International Mechanical Code (IMC)
- 2024 International Plumbing Code (IPC)
- 2024 International Existing Building Code (IEBC)
- 2024 International Residential Code (IRC)
- 2024 International Fire Code (IFC)
Key Changes: ASCE 7-16 vs ASCE 7-22
| Feature | ASCE 7-16 | ASCE 7-22 |
|---|---|---|
| Wind Directionality (Kd) | In qz equation | Moved to pressure equations |
| Tornado Loads | Commentary only | New Chapter 32 (required) |
| C&C Roof Zones | Multiple zones | Reduced to 3 zones |
| Minimum EWA | Various | 10 sq ft minimum |
| Simplified Methods (Part 2) | Available | Removed |
| Elevated Buildings | Not addressed | New Section 27.3.1.1 |
| Ground-Mounted Solar | Limited guidance | New Section 29.4.5 |
For most Colorado projects, ASCE 7-22 generally produces same or slightly lower pressures than ASCE 7-16. However, tornado loads in Chapter 32 may apply to eastern Colorado for Risk Category III and IV structures.
Windows, Doors & Fenestration Requirements
Per IBC Chapter 16, buildings, structures, and parts thereof shall be designed to withstand minimum wind loads. Wind loads on fenestration (windows, doors, skylights) shall be determined in accordance with ASCE 7 Chapters 26-30.
Design Pressure (DP) Ratings
Design Pressure (DP) equals the maximum wind pressure a window or door can resist:
| DP Rating | Positive Pressure | Negative Pressure |
|---|---|---|
| DP 15 | +15 psf | -15 psf |
| DP 25 | +25 psf | -25 psf |
| DP 35 | +35 psf | -35 psf |
| DP 50 | +50 psf | -50 psf |
| DP 65 | +65 psf | -65 psf |
Selection Rule
The product DP rating must exceed the calculated Component & Cladding (C&C) pressure for that location. Zone 5 corners require higher ratings than Zone 4 field areas.
Impact Resistance - NOT Required in Colorado
Colorado is NOT within a wind-borne debris region
Wind-borne debris regions are defined as areas within 1 mile of coastal mean high water line where V ≥ 130 mph, areas where V ≥ 140 mph, and Hawaii.
Since Colorado is an inland state without hurricane exposure, impact-resistant glazing and hurricane shutters are NOT required by code. Standard wind load design provisions apply.
Deflection Limits for Fenestration
When framing members support glass:
| Span Length | Maximum Deflection |
|---|---|
| Up to 13'-6" | L/175 |
| Over 13'-6" | L/240 + 1/4" |
Applied at 0.6 times the C&C wind loads
Roofing Requirements & Standards
IBC Chapter 15 provides minimum requirements for the design and construction of roof assemblies and rooftop structures. The following ICC/IBC references apply to Colorado projects based on locally adopted code editions.
IBC 2024 Chapter 15 - Section 1504 Performance Requirements
Section 1504.1 General:
"Roof decks and roof coverings shall be designed for wind loads in accordance with Chapter 16 and Sections 1504.2, 1504.3, and 1504.4."
Section 1504.3 Wind Resistance of Non-ballasted Roofs:
Roof coverings mechanically attached or adhered to the roof deck shall be designed to resist the design wind load pressures for components and cladding per Section 1609.5.2.
Asphalt Shingles (IBC Section 1504.2)
| Wind Speed | Required Classification | Test Standard |
|---|---|---|
| ≤ 110 mph | Class D | ASTM D7158 |
| > 110 mph to ≤ 120 mph | Class G or H | ASTM D7158 |
| > 120 mph | Class H | ASTM D7158 |
Standard calculations assume Exposure B or C, height ≤ 60 ft. Additional calculations required for other conditions.
Clay and Concrete Tile (IBC Section 1504.3)
- Wind loads per IBC Section 1609.6
- Testing per SBCCI SSTD 11 or ASTM C1568 (overturning resistance)
- Wind tunnel testing per ASTM C1569 for tiles not meeting Chapter 16 limitations
Slate Shingles (IBC Section 1504.4.4) NEW in IBC 2024
- Testing per ASTM D3161 (Fan-Induced Method)
- Classification per IBC Table 1504.2
Metal Edge Systems
- Design per IBC Chapter 16
- Testing per ANSI/SPRI ES-1 (Methods RE-1, RE-2, RE-3)
UL 580 - Roof Uplift Resistance Standard
UL 580 (Standard for Tests for Uplift Resistance of Roof Assemblies) classifies roof assemblies by uplift resistance:
| UL 580 Class | Uplift Pressure Rating |
|---|---|
| Class 15 | 15 psf |
| Class 30 | 30 psf |
| Class 60 | 60 psf |
| Class 90 | 90 psf |
| Class 120 | 120 psf |
UL 580 Test Procedure
- Specimen Size: 10 ft × 10 ft (100 sq ft) test specimen
- Loading: Static and dynamic (cyclic) pressure loading
- Criteria: Assembly must maintain attachment integrity without excessive deflection
Tornado Load Provisions (ASCE 7-22 Chapter 32)
Eastern Colorado Tornado Considerations
Chapter 32 of ASCE 7-22 introduces tornado load requirements:
- Design required where tornado speed (VT) > 60 mph
- Applies to Risk Category III and IV structures
- Primarily affects areas east of the Rocky Mountains
- Higher uplift classifications may be needed in tornado-prone regions
For Colorado: Most of Colorado west of the mountains is outside the primary tornado corridor, but eastern Colorado (plains region) may require tornado load consideration for certain building types.
Roofing Reference Standards Summary
| Standard | Description | Application |
|---|---|---|
| ASTM D7158 | Wind Resistance of Asphalt Shingles | Shingle classification (D, G, H) |
| ASTM D3161 | Wind-Resistance of Steep Slope Roofing (Fan-Induced) | Slate shingles |
| ASTM C1568 | Concrete/Clay Roof Tile Wind Resistance | Tile overturning resistance |
| ASTM C1569 | Concrete/Clay Tile Wind Tunnel Testing | Non-standard tile configurations |
| SBCCI SSTD 11 | Wind Resistance of Concrete/Clay Tile | Alternative to ASTM C1568 |
| ANSI/SPRI ES-1 | Wind Design Standard for Edge Systems | Metal edge, fascia, coping |
| UL 580 | Tests for Uplift Resistance of Roof Assemblies | Complete roof assembly classification |
Colorado Exposure Categories
| Category | Description | Typical Colorado Application |
|---|---|---|
| Exposure B | Urban/suburban, wooded areas | Default for most Front Range cities |
| Exposure C | Open terrain, grasslands | Eastern plains, mountain valleys |
| Exposure D | Flat, unobstructed coastal areas | Not applicable in Colorado |
High Wind Areas in Colorado
Certain Colorado locations experience elevated wind speeds:
- Mountain passes and ridges - can experience extreme wind events
- Foothill transitions (Boulder, Golden) - Chinook/downslope winds
- Eastern plains - tornado potential and open exposure
Always Verify Site-Specific Wind Speeds
Use ASCE 7 wind speed maps or the ASCE 7 Hazard Tool to determine accurate wind speeds for your specific project location.
Colorado City Wind Load Pages
Colorado Solar PV Wind Load Requirements
Colorado is a leading state for solar energy with over 300 days of sunshine annually. The state's high elevation and abundant sunlight make it an ideal location for both residential and utility-scale solar installations. Understanding wind load requirements is critical for proper solar panel design and installation.
Why Solar Wind Loads Matter in Colorado
- Elevation Benefit: The Ke factor reduces wind pressures by up to 22% at 10,000 ft elevation
- Mountain Winds: Chinook and downslope winds can produce localized high-wind events
- Utility-Scale Projects: Large solar farms on the Eastern Plains require careful exposure analysis
- ASCE 7-22: New Section 29.4.5 provides guidance for ground-mounted fixed-tilt systems
ASCE 7 Solar Panel Provisions
| Section | Application | Description |
|---|---|---|
| 29.4.3 | Low-Slope Roofs (≤ 7°) | Rooftop solar on flat or nearly flat roofs |
| 29.4.4 | Parallel to Roof Surface | Flush-mounted panels on any roof slope |
| 29.4.5 | Ground-Mounted (ASCE 7-22) | Fixed-tilt ground-mount systems |
| Chapter 27 | Ground-Mounted (≤ 45°) | Treated as open building with monoslope roof |
Solar Wind Pressure Formula
ASCE 7 Solar Panel Wind Pressure
Colorado Elevation Advantage for Solar
Colorado's high elevation provides a unique advantage for solar installations. The Ke ground elevation factor reduces velocity pressure, which directly reduces design wind loads on solar panels:
- Denver (5,280 ft): ~12% reduction in wind pressure vs. sea level
- Leadville (10,150 ft): ~22% reduction in wind pressure vs. sea level
This can result in lower design pressure requirements and potentially more economical mounting systems.
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