Designing Fire-Resistant Homes In Eastern Washington: Essential Tips And Strategies

After the devastating Gray Fire started on August 18, 2023, my parents' house in Medical Lake was lucky to survive while everything around it burned. The fire destroyed over 10,000 acres and 240 homes, forcing at least 5,000 residents to evacuate. Fortunately, my parents' house was untouched, protected by a combination of defensible space, resilient materials, irrigated areas around the house, and some good luck.

Wildfires in Eastern Washington are on the rise. According to a 2019 report by the Washington State Department of Natural Resources, Leavenworth tops the list of the 25 areas most vulnerable to wildland fires. Other high-risk areas include Wenatchee, Chelan, Cashmere, Manson, Twisp, and Winthrop. These regions are significant to us as we frequently work in these areas, and wildfire risk is a pressing concern for our clients.

As wildfire activity becomes more common and destructive, designing homes that can withstand these devastating fires is more crucial than ever. With increasing amounts of fuel on our lands and the unpredictable, fast-moving nature of wildfires, homes in wildfire-prone areas are at significant risk. Wildfires often attack the exterior of a home first, making it essential to incorporate fire-resistant design elements. This article means to lay out some considerations for building and renovating homes to help reduce the risk of wildfire.

Choosing the Right Materials

Selecting the right materials is crucial when designing a home to withstand wildfires. Here are some key considerations:

Fire-Resistant Materials:

Opting for materials that are inherently resistant to fire can significantly reduce the risk of your home catching and spreading flames. Metal, cement board products, stucco, some composite materials, fire-treated wood, and heavy timber are excellent choices for siding and other exterior elements. These materials are less likely to ignite and can provide an additional layer of protection against the intense heat and embers that wildfires produce.

Roofs:

The roof is one of the most critical parts of a home when it comes to wildfire defense. Choosing roofing materials with a Class A fire rating helps mitigate the ability of a fire or embers to ignite your roof material. Class A rated roof materials represent a flame spread of 0-25, meaning they do not easily catch or spread fire. Materials such as metal, clay tiles, and composite shingles with a Class A rating can help protect your home from airborne embers and direct flame contact. While not common, fire-rated sheathing (OSB or Plywood) can add an extra layer of protection and peace of mind to someone living in a very fire prone area.

Home Detailing

When designing a home to be resilient against wildfires, proper attention to detail can make a significant difference. Many homes catch fire due to improper detailing and below are a few of the most critical areas to consider.

House Meets Ground:

The interface between a structure and the ground is a very common place for fires to take hold. Foundation/ crawlspace vents should include a metal mesh with openings no larger than 1/8” to ensure embers can’t be sucked in and catch fire in your crawlspace. Another critical area is where the siding ends atop the foundation wall. Ensuring that the bottom edges of plywood or OSB are property covered, gaps are sealed, and siding edges are not frayed or damaged will help reduce the ability of fire to propagate up the walls if something is burning on the ground.

Roofs:

Properly detailed and ventilated roof eaves can prevent embers from entering your attic. Use ember-resistant eave vents or metal mesh with openings no larger than 1/8” to keep out sparks and embers. Additionally, enclosing eaves with fire-resistant materials can provide an extra layer of protection by reducing the chance of embers catching on exposed wooden surfaces such as rafter tails or plywood/ OSB. Ensuring that gutters are regularly cleaned or designed to prevent debris build-up is another way to reduce the chance of embers igniting a roof.

Decks:

Decks can be particularly hazardous during a wildfire, as they often provide an easy place for flames to spread. Use a concrete patio, if possible, for your project rather than a deck. If a deck is necessary, minimize its exposure to potential fire sources by designing it to be as enclosed and low to the ground as possible. Avoid using traditional wood decking and instead opt for fire-resistant composite materials or heavy timber that is less likely to ignite. Where decks are exposed on the underside, provide a skirt of 1/8” metal mesh to help reduce the ability of an ember to find its way underneath.

Sprinkler Systems:

Sprinkler systems designed within a home are intended to allow additional time for residents to get out safely in the event that the home catches fire. These systems are critical for life safety but are not designed or intended to save your home from a catastrophic fire. There are, however, exterior sprinkler systems that can be installed on roofs and around the base of a house to help keep things wet during a wildfire and help reduce the chances of a total loss. These are typically not automated and require someone to turn them on if needed.

Defensible Space

Defensible space is an area maintained around a structure with the purpose of reducing risk to fire danger. The general idea is to reduce and remove fuels around your house so that it’s less likely to catch fire. This is probably the simplest and most effective way to reduce the risk of wildfire around your home. Here are some key strategies:

Open Areas:

Maintain a clear space around your home by removing any combustible materials and keeping the area free of debris. This open area helps to reduce the chances of a wildfire reaching your home and provides a defensible zone for firefighters.

Vegetation:

It’s important to manage the vegetation around your home carefully. Avoid having large trees within 30 feet of the house, as they can easily catch fire and spread flames to your home. Regularly clear undergrowth and dead plant material, which can serve as fuel for a fire.

Ground Cover:

Use non-combustible ground cover like gravel or maintain irrigated green areas close to your home. These materials are less likely to catch fire compared to dry grass or mulch. Keeping the ground cover well-irrigated can further reduce fire risk.

Plant Selection:

Select plants that are less prone to catching fire. Avoid fire-prone species such as arborvitae, which can act as fuel for a wildfire. Instead, choose fire-resistant plants that retain moisture and are less likely to ignite. Here is a very thorough guide to fire-resistant plants from the Washington State Master Gardener Program.

Grant Programs:

Look into local grant programs that can help fund the creation and maintenance of defensible space around your home. These programs can offer financial assistance, making it more affordable to implement necessary fire-resistant improvements.

Here is a list of available resources in the Leavenworth area courtesy of the Chumstick Wildfire Stewardship Coalition.

Conclusion

As wildfires become more frequent and severe, implementing fire-resistant materials, home detailing, and maintaining a defensible space are essential steps in safeguarding properties in high-risk areas. By educating homeowners on these critical measures, we can increase the resilience of homes, protect lives, and reduce the devastating impact of wildfires. Preparing our homes with thoughtful design and strategic planning is not just a necessity but a responsibility, ensuring that we are ready to face nature's unpredictability with confidence.