With wildfires becoming increasingly frequent and severe, protecting your home and family is more important than ever. This article covers essential topics like home hardening, creating defensible space, and understanding the Wildland-Urban Interface (WUI) and Fire Hazard Severity Zones (FHSZ).
Our goal is to raise awareness and provide practical tips to enhance your home's wildfire resilience. Start learning how to fortify your home and surroundings against the threat of wildfires today.
Key subjects include:
Understanding these basics and taking action can significantly improve your home's chances of surviving a wildfire.
1 Understanding WUI and FHSZ
Wildfire defense is crucial in California for those living in the Wildland-Urban Interface (WUI) – areas where human development meets wildlands. These zones are particularly vulnerable to wildfires, making awareness and preparation essential.
With wildfires becoming more frequent and destructive, we must understand some basic terminology, their designations, and what we can do to protect our property.
You may have seen homes remain intact while nearby homes were burnt to the ground after a wildfire. Significant research has recently been conducted to show proven effective methods for avoiding total loss, and we will introduce you to these methods in our next part, Wildfire Hardening Strategies.
Understanding the Wildland-Urban Interface (WUI) and Fire Hazard Severity Zones (FHSZ) is not just a matter of knowledge. It's a matter of safety. Knowing if your neighborhood and property are within these high-risk areas is crucial for your wildfire defense strategy.
Wildland-urban interface (WUI) refers to regions where homes and businesses are close to wildland vegetation, increasing the risk of wildfire exposure. Fire Hazard Severity Zones (FHSZ) refer to areas classified by the state based on their wildfire risk level. Very-high and High-risk zones require stricter building and vegetation management standards.
It's vital to grasp the dynamic nature of the WUI and FHSZ maps. These areas are not static; the WUI zone expands by about 2 million acres annually due to human development and increased density. The new FHSZ maps, for instance, were just released earlier this year. This underscores the need for regular updates and vigilance in your wildfire defense strategy. You can use the link embedded to verify if your property is located in WUI and its Fire Hazard Severity Level.
2 Wildfire Hardening
With extensive studies by USGS on 40,000+ structures across the state and post-fire analysis on Camp Fire, home characteristics that are effective against wildfire have been collected and analyzed. Below are methods with a priority level. The list below was created based on its priority and effectiveness:
Maintenance: This is the most critical and important part of protecting against wildfire. Routinely inspect the roof, gutter, wall, and patio areas to avoid the collection of debris and dry leaves; make sure the overhanging vegetation and tree branches are kept at a minimum of 10' away from the structure.
Roofing: Use fire-resistant, Class A roof covering materials like metal, clay, or asphalt shingles. Alternatively, make the roof assembly fire-resistant. For example, treated wood shake (Class B) with metal roof coverings or gypsum products like DensDeck beneath (per manufacturer requirements). Ensure the roof edges are protected to prevent embers from getting under and past the fire-resistant surface.
Vents: Protect vents to prevent flying embers from entering your home. Most of the homes lost in wildfires were ignited from within. The vents include attic vents, eave vents, soffit vents, and crawl space (foundation) vents, which all need to be covered with non-combustible mesh screen (usually steel, with a minimum of 1/16" and a maximum of 1/8" openings) to prevent ember (and rodent) intrusion.
Deck: Construct the entire deck, including joists, posts, and railings, with noncombustible materials like metal, fiber cement, or fire-retardant-treated wood.
Gutter: Use noncombustible materials such as aluminum, copper, or galvanized steel, and cover the gutter with a noncombustible leaf guard. Examine the roof edge and shield exposed wood materials with a metal drip edge.
Windows, skylights, and Doors: For better fire resistance, use dual-pane tempered glass windows and metal or solid-core wood doors. Do not use plastic window frames or ceramic glass. Cover the gap beneath doors, including the garage door, to
Fences: Use non-combustible materials if within 5' (zone 0) of the building. Avoid design (plank on both sides) that can trap debris and embers.
Eaves and Soffits: Cover with non-combustible materials to reduce vulnerability.
Sidings: Avoid vinyl, non-treated wood, or exterior insulation finish systems (EIFS) unless installed with a non-combustible base to make the wall assembly fire-resistant (similar to the roof assembly concept).
Before replacing your roof deck or any exterior building components, make sure you also check CalFire's home hardening tips and talk to your local Fire District about their requirements.
Photo Credit: Sandy Huffaker/Getty Images
3 What is Defensible Space?
Defensible space is the buffer created between your home and the wildland area that helps prevent the spread of wildfires. It is essential for protecting your property and ensuring the safety of your family and community. Defensible space is divided into zones, each with specific guidelines.
Zone 0 (0-5 feet), Ember-Resistant Zone:
The Zone 0 was introduced very recently, in 2020. This is the immediate zone around your house and should be free of all flammable materials. Use hardscape materials such as gravel, pavers, and concrete. Regularly remove dead vegetation and any combustible items. This is an extension of your home, which should be free of flammable materials, including storage. Keep branches trimmed 10 feet away from chimneys and stovepipes.
Zone 1 (5-30 feet), Home Protection Zone:
Remove dead plants, trees, and combustible materials. Keep vegetation well-watered and maintained; healthy, indigenous plants have evolved and become more resistant to natural wildfire. Trim trees regularly to keep branches at least 10 feet from other trees and from your home. Prune flammable plants and shrubs near windows and remove them from under decks, balconies, and stairs. Examine your landscape and select plants carefully; plants with high oil content, like palm trees, catch fire and burn easily.
Zone 2 (30-100 feet), Reduced fuel/Thinning Zone:
To reduce the spread of fire, Create vertical and horizontal space between trees and shrubs. Use fire-resistant landscaping. Regularly mow grass and create breaks in vegetation to slow down fire.
The extension of defensible space can be applied to tasks such as maintaining emergency access for fire trucks and trimming overhanging vegetation to allow passage for emergency vehicles. Check with your local fire department to learn more about their specific requirements.
Many have installed sprinkler systems on their roofs and yards, but they should cover all areas where embers will land and keep the area wet. The system's performance depends very much on wind, radiant heat, and water availability, so this should be "supplemental" and not the primary method for wildfire mitigation.
For more information on defensible space, please check CalFire's and NFPA's website.
Image Source: NFPA
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