Understanding the Colorado Wildfire Resiliency Code is increasingly important for anyone designing or building homes in the Rockies. This overview explains how the code works, where it applies, and what design and construction professionals need to know to ensure their projects meet new requirements.
Key Takeaways
- The Colorado Wildfire Resiliency Code establishes minimum standards for new construction in Colorado's wildland-urban interface (WUI)
- Local CWRC enforcement is required as of July 1st, 2026
- The state CWRC map classified WUI areas by fire intensity, which determine structure hardening requirements
- Under Class 2 structure hardening, exterior wall coverings must be noncombustible, ignition-resistant, or FRTW
Colorado Wildfire Resiliency Code Overview
The Colorado Wildfire Resiliency Code (CWRC) is the first statewide building code for new construction and additions in Colorado's wildland-urban interface (WUI). Prior to adoption of the CWRC, building codes varied by county, as Colorado is a home rule state. The CWRC establishes mandatory statewide minimum standards that local jurisdictions must adopt and enforce.
Despite CWRC adoption being mandatory, local jurisdictions still have the power to interpret the code and adopt stricter requirements as needed. Local code officials have final say on project permits and local code enforcement.
The purpose of the CWRC is to protect human life and property in wildfire-prone areas. Wildfire risk in Colorado has steadily increased in recent years, and the CWRC is intended to mitigate that risk by making communities more resilient to wildfires.
CWRC Timeline
The CWRC was adopted on the state level by the Colorado Wildfire Resiliency Code board in July 2025. The local adoption deadline was April 1st, 2026. The local enforcement deadline was July 1st, 2026.
Any project plans submitted after local enforcement must comply with applicable structure hardening requirements.
CWRC Applicable Projects
The CWRC applies to new construction and significant additions or alterations in WUI areas. Under the state code, significant additions or alterations are defined as projects where 25% of the surface area is replaced. Additionally, any projects over 500 square feet in surface area are subject to the code.
The CWRC is not retroactive. Any existing projects, small additions or alterations, and other projects such as repairs to historic structures are exempt from structure hardening requirements. Still, local jurisdictions may adopt stricter requirements. Consult local building officials for project-specific applicability questions.
CWRC Map: Fire Intensity Classifications
The CWRC applies to construction projects in Colorado’s wildland-urban interface (WUI). These WUI areas are classified by fire intensity (Low, Moderate, or High). These classifications were determined by factors such as vegetative fuels, topography, and weather conditions.
The state CWRC map displays fire intensity classifications in three colors (Low in yellow, Moderate in orange, and High in red). Areas not shaded on the CWRC map are urban and therefore not classified.
Under the CWRC, local jurisdictions may use the state map for enforcement, or they may create their own. For example, Jefferson County created their own WUI map for local enforcement using more accurate Jefferson County data. Always check with local jurisdictions to confirm project-specific fire intensity classifications.
CWRC Structure Hardening
CWRC fire intensity classifications determine structure hardening requirements. Under the model state code, Low intensity areas fall under Class 1 structure hardening, while Moderate and High intensity areas fall under Class 2 structure hardening.
Class 1 Structure Hardening
Under Class 1 structure hardening in Low intensity areas, only three components are subject to structure hardening:
- Roofs
- Gutters
- Ventilation openings
Class 2 Structure Hardening
In Moderate and High fire intensity areas, applicable projects must meet both Class 1 and Class 2 structure hardening requirements for the following components:
- Eaves & soffits
- Fascia
- Exterior walls
- Decking
- Windows
- Doors
- Detached accessory structures
Notably, under Class 2 structure hardening, exterior wall coverings are limited to noncombustible material, ignition-resistant material, or fire-retardant-treated wood (FRTW). The only exception in the CWRC model code is vinyl siding with a noncombustible or 1-hour fire-rated wall assembly.
Local jurisdictions may adopt stricter requirements and interpret the model code as needed. Application-specific requirements for permitting may vary slightly from one county to the other.
Summary: Ensure CWRC Compliance
Going forward, design and construction professionals working in Colorado's wildland-urban interface must consider structure hardening requirements. Project plans for new construction and significant renovations in WUI areas must specify compliant materials.
Local jurisdictions have the authority to interpret new wildfire codes and enforce them. Always check local wildfire codes before submitting proposals, as local jurisdictions may adopt stricter requirements than the model state code.
CWRC-Compliant Natural Wood Materials
For projects subject to Class 2 structure hardening requirements, natural wood is still an option. Design professionals can continue to specify real wood for siding, soffits, and decking so long as the materials meet specific standards for fire resistance.
Ignition-Resistant Wood
Some wood materials are naturally ignition-resistant. For example, Golden Balau is a tropical hardwood with high material density. Ignition-resistant wood has Class A flame spread according to a 30-minute ASTM surface burning test.
Ignition-resistant wood is suitable for eaves and soffits, fascia, siding, and decking under Class 2 structure hardening.
Fire-Retardant-Treated Wood
Softwood species such as cedar and hemlock may be pressure treated with fire resistant chemicals to meet Class 2 structure hardening requirements. FR treatment is a one-time treatment that makes standard wood materials fire-resistant.
Fire-retardant-treated wood (FRTW) meets Class 2 structure hardening requirements for eaves and soffits, fascia, siding, and decking material under Class 2 structure hardening.
Learn more about FRTW products in-stock in Colorado on our Wood Source FR Collection page.
