New Fire Hardening Building Code: Impacts to your home improvement and new construction projects

The City of Louisville has adopted Ordinance 1891, series 2025, which establishes a Fire Hardening Code to enhance building safety against wildfire risks. This code sets minimum fire-resistant construction standards for residential and commercial structures to reduce wildfire threats and mitigate the spread of fires between buildings.

The ordinance applies to new constructions, accessory structures, and repairs or replacements of certain home systems, which must comply with specific fire hardening standards.

What you need to know as resident

The new requirements apply to new construction and repairs or replacements of structures such as decks and fences. Talk to your contractor to ensure they have a permit for your project, and that they are aware of the requirements outlined below. 

New requirements include:

• Fencing. Fencing within 5 feet of the home or commercial building must be Class A per ASTM E84 standard meaning it has a Flame Spread Index of 25 or less or use an ignition resistant material such as metal, masonry, or stone.
• Decks. Deck surfaces and railings must be Class A per ASTM E84, standard meaning it has a Flame Spread Index of 25 or less.  Metal railings are acceptable.  Areas below decks 6 feet or lower to the ground must also be covered with gravel placed over 6 mil plastic, or concrete slab to prevent growth of vegetation.
• Roof coverings. Roof coverings or shingles must be Class A per ASTM E108 or UL 790 standard. Class A Tests are applicable to roof coverings that are expected to be effective against severe fire exposure, afford a high degree of fire protection to the roof deck, do not slip from position, and are not expected to present a flying brand hazard. 
• Roof, attic, and foundation vents. Vents must be covered with metal mesh with1/8-inch or smaller openings.  
• Gutters. Gutters must be metal (vinyl not allowed) and the must include gutter guards to prevent to accumulation of debris.  
• Siding and eave materials.  Siding and eave material must be either cementitious siding (e.g. James Hardie Siding, Nichiha fiber cement), stone, or stucco, or any composite material Class A per ASTM E84 standard meaning it has a Flame Spread Index of 25 or less. 

Definition of Fire-Resistant Building Materials: Building materials shall exhibit a flame spread index not exceeding 25 and shall not show evidence of progressive combustion following the extended 30-minute test.

What you need to know as a contractor

It is the responsibility of the contractor to obtain a building permit and comply with fire hardening requirements. Read the ordinance containing the full requirements below.

Zoning & Design Regulations

Fire Hardening Code ordinance

Building Permit Information

If you need guidance, please contact our Chief Building Official, Chad Root, at CRoot@LouisvilleCO.gov or (303) 335-4580.

Why did the City implement this new code?

The code, developed in collaboration with the Louisville Fire Protection District and based on public feedback, is designed to safeguard public health and safety while balancing costs and feasibility. It was adopted by City Council to better protect the community against wildfire. Fire resistant materials enhance safety by making it more difficult for fire to spread quickly between buildings.

While implementation will require additional city resources, revenues from building permits will help offset expenses. By adopting this code, Louisville demonstrates its commitment to wildfire risk reduction and community safety.

For more details, read the ordinance that was passed on March 4, 2025.