In an unprecedented reversal of American history, the demographic landscape of the United States is undergoing a transformative shift. A growing number of Americans are choosing to relocate from major cities and metropolitan hubs to the outskirts, suburbs, and rural expanses, propelled by a multitude of factors. As individuals settle in and around diverse ecosystems such as forests, grasslands, and shrub lands—also known as wildland-urban interface (WUI) zone—ramifications of this population shift become more pronounced.
This migration trend unfolds against an increasingly pressing concern—climate change-induced wildfires across North America. The intricate interplay between human habitation and natural landscapes amplifies the challenges associated with wildfires. With rising temperatures and prolonged droughts heightening the risk of wildfires, a significant emphasis is placed on enhancing safety measures and protections in the WUI zone.
Introduction of Wildland Urban Interface Construction Codes
Over the years, with the escalating threat of wildfires, there has been a growing development of building codes tailored specifically for areas prone to wildfires.
The Wildland-Urban Interface (WUI) provisions are typically integrated into state or local building codes. California is known for introducing its own set of WUI zone construction requirements within the California Building Code (CBC) in 2008. CBC regulations mandate that building products intended for use in the WUI zone or State Responsibility Area (SRA) must adhere to specific directives. The WUI construction code primarily aims to enforce heightened standards for fire resistance and ignition resistance in the built environment.
A home or building designed and constructed with meticulous attention to detail and the use of compliant building materials significantly enhances its chances of withstanding a wildfire. There are two common ways to identify optimal building products for properties located in wildfire-prone areas: opting for WUI-Compliant building products or selecting products listed under CAL FIRE Building Materials Listing Program.
WUI-Compliant Building Products
WUI-compliant products generally refer to products and materials that meet specific standards and regulations outlined for the Wildland-Urban Interface zones.
According to California Building Code (CBC), the minimum requirement for building envelope components, such as siding/cladding is that an exterior wall covering or wall assembly, shall comply with one of the following requirements:
- Noncombustible material
- Ignition-resistant material
- Heavy timber exterior wall assembly
- Log wall construction assembly
- Wall assemblies that have been tested in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in ASTM E2707 with the conditions of acceptance shown in Section 707A.3.1
- Wall assemblies that meet the performance criteria in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in SFM Standard 12-7A-1.
CAL FIRE Building Materials Listing Program
CAL FIRE is a California state agency responsible for safeguarding natural resources within areas designated by the State Board of Forestry as State Responsibility Areas (SRA). In alignment with this mission, the Office of State Fire Marshal (OSFM) introduced the Building Materials Listing (BML) Program. This program serves as a comprehensive initiative aimed at evaluating and certifying a diverse array of building materials. Product manufacturers are required to pass rigorous testing conducted through laboratories accredited by the State Fire Marshal (SFM), ensuring their building materials meet stringent standards for the WUI zone.
The BML Program provide authorities, architects, engineers, contractors, and the fire services with a reliable and readily available source of information when they do not have a staff or subject matter expert to assess the building material quality.
Wood Cladding for Wildfire-Prone Areas
There is a common belief that wood, being perceived as combustible and flammable, is not considered a safe material in proximity to fire. As a result, wood is often not the first come to mind when selecting building materials for building structures in wildfire-prone areas. As technology advances, reSAWN TIMBER co. addresses this challenge by innovatively modifying wood structures. The thermally modified wood offerings, Abodo and Sylva, can be more resistant to fire than untreated wood. The thermal treatment alters the chemical composition of the wood, leading to a decrease in the content of flammable substances within the material, while preserving the original aesthetic of wood.
reSAWN’s Abodo offerings are less likely to ignite and sustain combustion compared to untreated wood. When integrated with fire-rated sheathing or gypsum board to form the wall assembly, it delivers a structurally sound exterior wall approved and listed under the CAL FIRE Building Materials Listing Program.
As demographic trends evolve and more individuals relocate to wildland-urban interface (WUI) zones, architects, builders, and homeowners must stay well-informed about the escalating wildfire risk. This necessitates diligent research, selecting building materials by code requirements, and preserving aesthetic appeal throughout the construction process. Contact us to learn about what product works best for your project.