On this page, you’ll learn how wind-driven embers can ignite homes in Serrano—and the practical steps homeowners can take to reduce that risk.

Embers

Now picture strong winds driving embers directly toward a house like the one in the sketch—with a fire-rated roof, stucco siding, dual-pane windows, exposed eaves, bark mulch along the base, and shrubs beneath windows and eaves.

Here’s what can happen:

Embers strike vents in the foundation, eaves, and gables. Some pass through oversized screens and land on combustible materials in the attic or crawlspace—where a hidden fire can quietly begin.

Embers land on the roof, roll downward, and collect in gutters filled with combustible debris—one of the most common places where ember ignitions occur. Once the debris ignites, flames can spread to the roof sheathing and exposed rafter tails.

Other embers are swept up under the eaves, where they search for gaps and crevices to lodge and ignite roofing materials—potentially allowing fire to reach the attic.

Many embers bounce off noncombustible stucco or stone walls, fall to the ground, and swirl along the base of the home—collecting in bark mulch, dry leaves, yard debris, and shrubs.

Once ignited, shrubs can burn like a blowtorch—sending flames, radiant heat, and hot gases directly against windows and up into the eaves.

As flames intensify and radiant heat builds, the window eventually fails. Flames and embers enter the home, igniting interior materials and allowing the fire to spread from room to room.

At the same time, flames and intense heat can fill the eaves. If combustible eaves are exposed, they may ignite, allowing flames to spread into the attic.

That’s how embers from a distant wildfire can quickly turn into a house fire within minutes.

Before

After

Wind

Risk Reduction

The way to reduce the risk of home ignition is to keep embers, flames, and radiant heat from entering the house in the first place. The following practical measures are supported by post-wildfire damage assessments and fire science research. Sources are listed at the bottom of this page.

High Risk

Lower Risk

• Replace old-style 1/4-inch mesh vents with commercially available ember-resistant vents or cover them with 1/8-inch or 1/16-inch mesh. Verify proper ventilation with a professional roofer.

• Replace garage door weatherstripping if gaps exceed 1/8-inch to prevent swirling embers from entering.

Keep Embers Out

Embers can enter the house directly through vents in the foundation, eaves, gables, and roof, and through gaps around garage doors.

Keep Flames and Radiant Heat Out

Flames and radiant heat can enter the home through windows and from ignited eaves.

Gutters

Embers can melt vinyl or plastic gutters and ignite debris inside them, allowing flames to reach the roof edge and potentially spread into the attic.

To reduce gutter ignition risk:

• Clean gutters before fire season

• Install non-combustible metal gutters

• Use metal gutter guards

Eaves

Most Serrano homes have exposed rafter-tail eaves where wind-blown embers and radiant heat can collect. This area can allow fire to enter the attic—one of the most common pathways leading to home loss during a wildfire.

Fire research and post-wildfire studies show that homes with enclosed eaves survive at much higher rates than those with exposed rafter tails. Furthermore, exposed eaves on single-story homes are often at even greater risk because they are closer to ground-level fuels like shrubs, bark mulch, and wood fencing.

Enclosing eaves means covering the open underside with noncombustible soffit panels—creating a solid barrier that resists radiant heat and blocks embers and flames. The challenge is cost. Homeowners in Serrano report estimates exceeding $10,000 to enclose production home eaves.

Enclosed

Exposed

• Seal gaps in the eaves larger than 1/8-inch. Small openings can trap wind-blown embers and allow them to lodge in combustible areas of the eave structure.

• Remove shrubs located directly under eaves. When shrubs ignite, they can send flames and intense radiant heat along the underside of the eaves. Eliminating shrubs below the eaves removes this direct flame pathway.

There are other options that can make a meaningful difference, if enclosing your eaves isn't economically feasible:

Windows can be upgraded—replacing vinyl frames with aluminum frames and installing two tempered glass panes. However, these structural retrofits are very costly and may only delay failure under extreme radiant heat.

Alternatively, moving bark mulch, shrubs, and tree limbs away from the house, and replacing the wood gate and the attached wood fence section with metal, will greatly reduce the chance that flames and radiant heat near the house will build to levels that cause window failure and ignite exposed eaves.

The key question is: how far is far enough?

Post-wildfire damage assessments and laboratory testing consistently show that maintaining at least five feet of noncombustible space along the sides of the home and around decks—and spacing vegetation from five to thirty feet—provides significant risk reduction during high-wind ember events.

Windows are the highest risk structural feature in Serrano because:

1. Window glass transmits radiant heat inside that can ignite curtains, shutters, furniture, etc., near the window before the window fails.

2. Vinyl frames begin to melt at 180 degrees F, causing annealed glass to crack and tempered glass to fall to the ground. The building code and HOA design guidelines allow vinyl window frames in Serrano.

Windows

3. If the window frame remains intact, annealed glass panes fail next. If there is a tempered glass pane, it will fail after the annealed glass fails.

Additional Vulnerabilities

Several additional structural features in Serrano can increase wildfire risk and are not addressed here, including:

• Combustible shutters

• Operable skylights with 1/4-inch mesh screens

• Attached, unenclosed structures made of combustible materials

• Decks constructed with combustible materials

• Hot tubs located near the home

Sources

Vents and Eaves

Brown, C., et al. Eave and Vent Experiments (EaVE) Phase A. NIST Technical Note 2341

Quarles, S. Vulnerability of Vents to Wind-Blown Embers. IBHS. August 2017.

Quarles, S., et al. Vulnerabiltity of the eave to direct flame contact and radiant exposure. Conference Proceedings Fire and Materials 2011.

Windows

Schrader, R., et al. Experimental Study of Heat Transfer Through Windows Exposed to a Radiant Panel Heater. Fire Technology. January 2025.

Willi, J., et al. Window Pane Failure During Exterior Fire Exposure. Fire Technology. December 2024.

Fences

Butler, K., et al. Wind-Driven Fire Spread to a Structure from Fences and Mulch. NIST Technical Note 2228. August 2022.

Mulch

Quarles, S. and Smith, E. “The Combustibility of Landscape Mulches.” University of Nevada Cooperative Extension. 2011.

Vegetation

Hedayati, F., et al. Near-Building Noncombustible Zone. IBHS. December 2getation in Zone 0: Amplifying Damage to Structures. IBHS. December 2025

General

Builder’s Guide to Construction in Wildfire Zones. FEMA P-737. December 2025.

California 2025 Wildland-Urban Interface Code. Title 24 Part 7.

Wildfire Prepared Home Standard. IBHS

Hedayati, F., et al. WILDLAND FIRE EMBERS AND FLAMES: Home Mitigations That Matter. IBHS Research. April 2023.