Angelenos are not new to the threat of wildfire. Each year wildfire season seems to stretch longer than the year prior. We adapt to poor air quality days, evacuations, and are watchful of the news when fires break out in hillside areas. The Palisades and Eaton fires that began on January 7, 2025 were different. The reach of those fires into our dense urban fabric left us questioning the vulnerability of ALL our neighborhoods, not only those within the wildfire urban interface (WUI). The loss is incomprehensible. As architects, we reflect on our role and responsibility to our community. It is not enough to merely design to current code. If our goal is to design timeless homes, they must also be built to withstand the environmental pressures of a changing climate.
Our team is committed to designing architecture that is beautiful, functional, sustainable, and resilient. We are actively researching and integrating fire resilient features into our designs. These features can be categorized as “passive” and “active”.
Passive Design
Passive design features are essential to fire resilience and the first place to start when designing a new home or retrofitting an existing home. It is critical to maintain defensible space around the perimeter of all buildings, eliminating connective fuel. Embers are the leading cause of structure loss, responsible for up to 90% of homes destroyed by wildfire. The zone between 0-5 feet around the perimeter of the home should have non-combustible ground cover or use fire-resistant or non-combustible materials for decks, porches, railings, and fences. This helps to prevent a fire from igniting in direct contact with the building from embers and creates a fire break by eliminating connective fuel from one structure to the next. Tall hedging in minimal sideyard setbacks, wood fences, and trash cans placed against the home are common features that should be reconsidered when designing a resilient home. The next zones, 5-30 feet and 30-100 feet, should limit density and size of planting to varying degrees. In these zones, planting should not be located near outbuildings. We collaborate with landscape architects to strategically plan gardens so that our homeowners can enjoy nature while protecting their home. Maintaining gardens by removing dry foliage on and around the structure as well as installing gutter guards are as important as the building design.
No building is fireproof, but we can improve its fire resilience through hardening the building envelope. The current high fire code already mandates Class A roof systems such as tile, asphalt, metal, and composite shingles. By adding a layer of roofing board like fire-resistant DensDeck below the roof finish material, we increase the length of time the roof assembly can withstand exposure to heat and fire. Similarly for wall assemblies, code requires non-combustible siding materials such as stucco, metal, and fiber cement siding. Adding a layer of wall board like DensGlass Fireguard behind the finish and waterproofing layer increases fire resistance. Another option we are considering for projects is to install fire- and heat-resistant exterior rigid mineral wool insulation behind the exterior finish layer.
Windows and skylights are vulnerable points in the building envelope as glass can only withstand certain levels of heat before breaking and allowing a clear path for embers into the interior. We have seen evidence of this from a past TBA project in the Pacific Palisades that was lost when a home burning nearby created such extreme heat that the windows shattered. Dual-pane windows with tempered glass on the exterior will withstand higher levels of heat than single-pane annealed glass. Triple-glazed windows, ceramic glass, and wire glass can withstand even higher heat levels. The window frame material is also an important factor in the resilience of a window. Metal-clad windows can withstand higher heat levels than an unreinforced vinyl window which will melt under extreme heat. Fire-rated window assemblies consider the performance of the entire unit.
Exterior vents in the building envelope are common entry points for embers if not designed properly. Installing a metal screen or layers of screen with 1/8” or smaller openings will prevent the passage of embers into attics, crawl spaces, and other vulnerable areas. We have seen many cases of lost homes where embers made it into an attic space. Once the fire ignited inside, saving the home became far more challenging. To avoid attic and crawlspace vents altogether, many of our homes in high fire zones are designed with sealed attics and crawlspaces. A sealed attic requires the use of closed cell spray foam insulation, which can be specified with fire retardant. Mineral wool insulation such as Rockwool ComfortBatt is another non-combustible insulation designed for fire resistance. Equally as critical as the assemblies themselves are the details of how they come together at building intersections and penetrations. We are improving our architectural details to ensure a continuous wildfire resistant barrier over the entire building envelope.
Building geometries also contribute to the resilience of a home. Simpler roof forms, shallow and closed eaves or soffits reduce opportunities to trap heat and embers. Decks should be made with non-combustible materials and enclosed undersides to prevent embers from gathering below. Other passive measures we are researching are the benefits to alternative structural materials such as steel framing and ICF blocks, and fire-retardant paint.
Active Strategies
Active strategies are not a replacement for designing with passive resilient features but can have a big impact. Rooftop and perimeter fire sprinklers with water or foam create a high moisture environment by saturating the roof and exterior walls before embers and fire arrive. It is important to pair these systems with an independent source of water like a pool or cistern and connect them to a backup power source like a generator or electric battery storage. As we learned during the recent fires, municipal water and power may not be available when you need it. Certain exterior sprinklers systems offer wind-resistant spray heads and the ability to operate from your phone. Other sprinkler systems focus on spraying the landscape with fire retardant to prevent the fire from getting close to the structure. Metal roll-down shades or shutters can be added to the exterior of a home to protect windows. Active measures can also include providing useful equipment to fire fighters after you have evacuated. A water canon or portable pool pump is not a large expense and making one available to firefighters where hydrant access is limited can make a huge difference as they fight to save your home. Other active assistance can take the form of advocacy or supporting measures that prepare our communities for future fire events.
The strategies we mention above are by no means a complete list of all options. We share them to increase awareness and to encourage others to research and share resources. We live in urban communities, close to our neighbors. It is not enough for one home to be designed and maintained resiliently. The commitment must be shared by all so we can collectively build more prepared communities and prevent another disaster of this scale from occurring.
Helpful Resources
Project Recovery – Urban Land Institute
Fire Recovery – AIA California
California Wildfire Rebuilding Guide – USGBC California
Wildfire Risk – Insurance Institute for Business & Home Safety
Hardening for Wildfire Resilience – AIA California
Wildfire Division – National Fire Protection Association (NFPA)
State Fire Marshal’s Building Materials Listing Program – Cal Fire
Passive Fire Protection – Rockwool
Fire & Ember Safe Vents – Vulcan Vent