Wildfires have become a common topic and focus worldwide as they are becoming more frequent, intense, and challenging to contain. The rapid spread of wildfire into inhabited areas could cause devastating losses of life and health, as well as financial and property damages.
The Wildland Urban Interface (WUI) is a critical area where human development meets the natural, undeveloped landscape. The population is rapidly growing in the U.S., and more and more people and families are choosing to live in the outskirts, suburbs, and rural expanses. Housing development follows the population and grows into wildlands. As communities expand, the interface between wildlands and urban areas becomes increasingly prominent—a high-risk area when wildfires occur.
The Wildland Urban Interface is not static as it is constantly growing. The WUI zone varies across regions depending on climate, topography, vegetation, and land use. WUIs typically include suburban neighborhoods, recreational areas such as golf courses, and communities near natural landscapes. These locations are where wildfires have the most significant impacts on human lives. The latest information on WUI areas can be found on the official website of the local fire department.
Vegetation, topography, and human activities are three major factors of wildfire spread in the WUI areas. The lush greenery enhances the aesthetic appeal of residence placements. Its combination with natural topography, such as steep slopes, canyons, and ravines, provides mental solace for residents. However, when wildfires occur, the vegetation becomes fuel for wildfires, and the layout of the land can affect how quickly flames advance, adding complexity to managing and mitigating fire risks.
In addition to natural wildfires, human activities could pose fire risks in these interface zones. Recreational outdoor activities, agriculture, and urban development increase the likelihood of human-induced wildfires. Human activities elevate the probability of initiating fires and add challenges to emergency response and evacuation. Rapid urbanization and sprawling developments create numerous access points for fires, making it challenging for firefighting crews to swiftly contain blazes. Evacuating residents during a wildfire becomes a logistical puzzle, requiring meticulous planning and coordination among emergency services.
Mitigating and preparing for wildfires, particularly in wildland-urban interfaces, are critical concerns for the public and federal, state, and local governments. These efforts are essential to safeguard communities from potential losses and damages. Common fire mitigation strategies involve community planning, comprehensive fire and life safety regulations, and stringent building standards. Educating and preparing the local communities about the devastating effects of wildfires can help reduce human-ignited fires and improve emergency responses. Creating ample defensible space between structures by reducing vegetation helps decrease the speed of fire spread. Additionally, choosing WUI-compliant building materials during new and remodel construction can mitigate the impact of wildfires and minimize the risk of ignition.
Living on the edge of wildlands comes with the allure of natural beauty and the challenges of managing the inherent risks. The Wildland Urban Interface demands a proactive and collaborative approach to safeguard communities against the threat of wildfires. Through careful planning, education, and investment in firefighting resources, residents and policymakers can work together to create resilient communities that coexist with nature while minimizing the impact of potential disasters. As we continue to expand our urban footprint, understanding and addressing the complexities of the Wildland Urban Interface will be crucial for building a safer and more sustainable future.
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:
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.
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.
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.
In an unprecedented reversal of American history the US population is becoming less concentrated in urban areas. Many Americans are moving out of big cities and metropolitan areas en route to the suburbs, exurbs, and rural areas.
As more and more people live in and around forests, grasslands, shrub lands, and other natural areas—places referred to as wildland-urban interface, or WUI zones—problems related to wildfires are exacerbated. There are more wildfires due to human ignition. Wildfires that do occur pose a greater risk to lives and homes, they are hard to fight, and it becomes impossible to let natural fires burn.1National Academy of Sciences Furthermore, the expenses to reduce fire hazards, battle rapidly spreading fires, and protect homes and human lives have risen pointedly in recent decades.
What is the Wildland Urban Interface (WUI)?
The wildland urban interface consists of geographical areas where human development and infrastructure (e.g., cell towers, schools, water supply facilities, etc.) meet or intermingle with undeveloped wildlands.
They are locations where wildfires have their greatest impacts on people and property. WUI zones are of concern for the public, federal, state, and local governments, so wildfire mitigation and preparedness are necessary when living within WUI zones.
Where is the Wildland Urban Interface Within the US?
Across the United States, wildland-urban interface zones in areas within California, Utah, Arizona and Oregon are experiencing wildfires. California has the most densely packed WUI in the United States.2Rethinking the Wildland-Urban Interface. Currently, they have just over 11.2 million people living in about 4.46 million homes across 6.7 million acres. Six of the twenty largest wildfires in California history were part of the 2020 wildfire season. Five of the new wildfires ranking in the top 10 were all a part of the August 2020 lightning fires. 3California Department of Forestry and Fire Protection (CAL FIRE)
In the Pacific northwest and the lake states, forests are the predominant wildland fuel. In southern California, chaparral brush predominates. The plains states have grass and oak woodlands, New Jersey has Pine Barrens, and the southeast has pine and hardwood forests.4FEMA
Given that wildfires can occur in any wildland area; and the number of acres burned has been increasing; and the number of houses in the WUI is increasing, federal, state, and local government agencies are focusing more on promoting the concept of “fire-adapted” communities. 5USDA A fire adapted community is defined by the United States Forest Service as “a knowledgeable and engaged community in which the awareness and actions of residents regarding infrastructure, buildings, landscaping, and the surrounding ecosystem lessens the need for extensive protection actions and enables the community to safely accept fire as a part of the surrounding landscape.” 6The Fire Adapted Communities Learning Network
The Fire Adapted Communities Learning Network
Introduction of Wildland Urban Interface Construction Codes
As of January 2008, the 2007 California Building Code (CBC) went into effect along with the inclusion of Wildland Urban Interface building standards. For building products to be used in the (WUI) or State Responsibility Area (SRA), regulations require that building products comply with specific directives. In terms of fire resistance and ignition resistance the primary goal of the WUI code is to hold construction practices to higher standards in the built environment. When a home or structure is designed and built with attention to detail and careful consideration of complaint building materials, it increases the chances of a structure’s survival in a wildfire.
California Fire Standards for WUI Compliant Exterior Wood Products
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:
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.
The benefits of using real wood cladding with wall assemblies that meet the performance criteria set forth in SFM Standard 12-7A-1 are tremendous:
When compared to noncombustiblebuildingmaterials such as steel and masonry, using WUI compliant exterior wood cladding and wall assemblies offer a sustainable, environmentally friendly, carbon neutral solution.
Ignition resistant fire-retardant-treated wood is impregnated with chemicals, so the use of paints, coating, stains or other visually pleasing surface treatments are not an option.
From an architectural and design perspective, WUI compliant exterior wood cladding has many aesthetically pleasing options to suite any project, with a bevy of species and finish options to choose from.
Exterior timber cladding is a versatile, timeless building material that works well in traditional or contemporary architecture.
Not only is real wood recyclable and biodegradable, but it also has strength, toughness, and durability that rivals many other exterior facade options on the market today.
reSAWN TIMBER co.’s Abodo® Vulcan Cladding was recently tested on an exterior wall assembly in accordance with the California Standards Code, Chapter 12-7A, SFM 12-7A-1 (Siding Materials for Exterior Wall Siding and Sheathing). The test simulated wildfire conditions using full size 4′ x 8′ panels that were exposed to a flame of 150 Kw for ten minutes. After, the panels were then observed for 60 minutes to check for further flaming. In order to gather accurate results, the process was repeated three times.
There is an absence of flame penetration through the wall assembly.
There is an absence of glowing combustion on the interior of the assembly after 70 minutes.
A test for siding in both a horizontal and vertical orientation is required to be sure of performance.
reSAWN TIMBER co.’s Abodo Vulcan Cladding is WUI Compliant
reSAWN TIMBER co.’s Abodo Vulcan cladding passed the test for both horizontal and vertical orientations for upcoming inclusion in the WUI Products Listing. A copy of the test results can be found here. The result? Abodo Vulcan cladding is now a compliant wildland urban interface building material.
SFM Standard 12-7A-1 Test Requirements
Test Results
Pass/Fail
Absence of flame penetration through the wall assembly at any time.
Flame penetration through the assembly was not observed during the full duration of the test
PASS
Absence of evidence of glowing combustion on the interior surface of the assembly at the end of the 70-minute test
Evidence of glowing combustion on the interior surface of the assembly at the end of the 70-minute duration for all three tests was not present
PASS
Abodo Vulcan thermally modified wood cladding is created from New Zealand plantation timber and engineered with a patented vertical grain orientation for superior weathering characteristics. A fine-sawn face provides beautiful grain depth and optimal coating performance.
Builders can rest-assured when choosing a wall assembly that combines reSAWN TIMBER co.’s Vulcan Cladding with fire-rated sheathing or gypsum board, the result is durable, CAL FIRE WUI compliant exterior siding that is impervious to hazardous weather conditions.
Since reSAWN’s Abodo Vulcan Cladding is pre-finished in modern, beautiful tones, architects and designers can confidently specify carbon negative, high performance, visually pleasing Vulcan exterior siding in wildland-urban interface zones. Clients are left with a stunning, natural, one-of-a-kind facade that can be easily maintained throughout the product lifecycle.
If you’d like to learn more about specifying reSAWN’s CalFire compliant Abodo Vulcan Cladding in Wildland Urban Interface zones, get in touch with us.
