Navigating the New Colorado Wildfire Resiliency Code

Colorado has set a new standard for community safety with the adoption of a statewide wildfire building code. On July 1, 2025, the Colorado Wildfire Resiliency Code (CWRC) was enacted, establishing minimum requirements for new construction and additions within designated Wildland-Urban Interface (WUI) areas. This measure is designed to enhance the resiliency of communities against the ever-increasing risk of wildfires. 

For trade professionals, understanding the CWRC is crucial for future projects. By April 1, 2026, all municipalities and counties in a WUI zone with the authority to adopt building or fire codes must adopt the CWRC as a minimum standard. These jurisdictions may also choose to enforce even stricter requirements. This post will guide you through the new code, its key dates, and why you should consider Hardie® fiber cement siding and trim for future projects. 

Understanding the CWRC Overview 

The core of the Colorado Wildfire Resiliency Code involves mandating specific fire-resistant building materials for structures in WUI zones. The requirements vary based on the zone's fire intensity classification.  

Low Fire Intensity WUI Zones 

For areas classified as Low Fire Intensity, the code requires Class 1 structural hardening measures. These include things like: 

• Class A roof coverings or assemblies 
• Noncombustible gutters 
• Ember and flame-resistant vents 

Moderate or High Fire Intensity WUI Zones 

Projects in WUI zones with Moderate or High Fire Intensity classifications face more stringent rules. These areas must incorporate both Class 1 and Class 2 structural hardening materials. This includes requirements for exterior walls, which must be constructed from one or more of the following: 

• Noncombustible materials 
• Fire-retardant-treated wood 
• Other ignition-resistant materials 

It is important to note that a significant alteration or addition to an existing structure greater than 500 square feet may also trigger the need for compliance with the CWRC. 

Key Implementation Dates 

To ensure you are prepared, keep this implementation schedule in mind: 

• July 1, 2025: The CWRC was officially adopted by the Wildfire Resiliency Code Board. 
• April 1, 2026: Local jurisdictions are required to adopt the CWRC. 
• July 1, 2026: Once adopted, the period to comply will follow the rules of the governing body or occur within three months of adoption, whichever is sooner. 

Building to the Highest WUI Code with Hardie^® Products 

For professionals seeking a reliable and fully compliant solution, Hardie^® fiber cement products offer a clear path to meeting CWRC requirements without the need for additional expenses, such as needing an additional layer of gypsum. Hardie^® siding is made of fiber cement and fulfills the requirements for Class 2 structural hardening in Moderate to High Intensity WUI areas. 

Here’s why Hardie^® products are an ideal choice for building in Colorado's WUI zones: 

• Noncombustible: Verified as noncombustible per ASTM E136, Hardie^® siding will not contribute fuel to a fire.* 
• High Fire Rating: It is Class A fire rated per ASTM E84, with a flame spread of 0. 
• Above-Code Solutions: If your project desires it or the local jurisdiction requires it, 1- and 2-hour fire-rated wall assembly designs featuring Hardie^® siding are available. 

Comparing Exterior Wall Materials 

Under the CWRC, several materials are compliant for Class 2 structural hardening, but they are not all equal in performance, complexity, or cost. 

• Hardie^® Siding: Fully compliant and won't contribute fuel to a fire. It is already a trusted material used on thousands of homes in Colorado each year. 
• Fire-Retardant-Treated Wood (FRTW): While compliant, this material will contribute fuel to a fire. It can also lead to increased costs over the life of the home due to material and maintenance needs. 
• Vinyl with 1-Hour Fire-Rated Assembly: This option is compliant but requires additional fire-rated components, which increases the complexity and cost of achieving compliance. It will also contribute fuel to a fire. 
• Brick/Stone or Stucco: These materials are compliant and won't contribute fuel to a fire, but they are often more expensive and labor-intensive. 
• Natural or Engineered Wood: These materials are not compliant with Class 2 structural hardening requirements, and even with a 1-hour assembly, these materials do not comply. 

Choosing Hardie^® products may help simplify compliance for exterior walls in Moderate to High Fire Intensity WUI zones. 

In fact, some Colorado trade professionals are already recommending Hardie^® products as a solution.  

“Colorado continues to strengthen its wildfire resiliency standards—which has been overwhelmingly positive for us,” says Ernest Lopez with GS Exterior Experts, a Colorado-based Elite contractor in the James Hardie^™ ALLIANCE. “We’ve already helped thousands of residential homes across Colorado upgrade from traditional wood or vinyl siding to Hardie^® siding as part of fire mitigation efforts. We try to educate every homeowner during the sales process about the importance of protecting their biggest investment, which includes choosing durable products.” 

An Added Benefit: Potential Insurance Discounts 

Selecting a durable exterior like Hardie^® fiber cement products can offer benefits beyond code compliance. Insurance companies may offer discounts for using materials known for their durability and ability to withstand the elements. In fact, a recent survey found that 7 out of 10 insurance professionals may offer a discount for fiber cement siding.** We recommend advising your clients to check with their insurance agents about potential savings. 

As Colorado moves toward a more resilient future, staying ahead of code changes is essential for your business. James Hardie has a local team ready to support you with product details, training, and more. To help you navigate these changes, we’ve published a detailed guide. It covers the CWRC requirements, a comparison of compliant materials, and how noncombustible* fiber cement products by James Hardie can play a role in building compliant projects in Colorado going forward.  

Get More: Download Our CWRC Guide  

*Hardie^® fiber cement products are noncombustible and/or have a Class A Flame Spread Rating when tested in accordance with ASTM E84. Fiber cement fire resistance does not extend to applied paints or coatings, which may be damaged or char when exposed to flames. The use of noncombustible siding, combined with other fire mitigation measures, may help harden a home against external fire. 

**Based on a survey of 50 U.S. insurance professionals conducted in January 2024 by B2B International.