Recent wildfires across the western United States have reignited the debate over fire-rated skylights. Are they truly necessary—or are they another checkbox in an ever-growing list of building requirements? More importantly, are we missing the broader story? In this post, we explore how skylights interact with fire safety, what the codes actually say, and how they may even support firefighting efforts when properly designed.
The Code Conversation: What’s Required and Where
In areas like California’s Wildland Urban Interface (WUI), building codes are designed to slow the spread of fire and protect structures. Fire-rated roofing assemblies are part of that approach, and skylights installed in those areas must meet specific standards.
Some of the relevant codes include:
- California Building Code Chapter 7A (WUI requirements)
- ASTM E108 / UL 790 Class A, B, or C fire ratings
- California Title 24, Part 6 (energy efficiency, but often overlaps with fire and material standards)
Most codes require that skylights within a certain proximity to wildfire zones meet Class A fire-rating—but this rating often focuses more on roof covering systems than on individual skylight components. The result? Some skylights with plastic glazing or thinner materials may technically meet the code but still perform poorly in high-heat or flame exposure. Others—like those using laminated glass with PVB (polyvinyl butyral)—may not be required but provide far better structural integrity during a fire.
Skylights as a Firefighting Tool: Cut or Keep?
There’s another perspective that often gets overlooked: the role of skylights during firefighting operations.
When a structure is burning, firefighters often cut ventilation holes into roofs to release superheated gases and smoke. This practice reduces flashover risk and improves visibility inside the building—buying critical time to locate victims and suppress the fire.
In these scenarios, skylights may actually assist with rapid roof ventilation—either by serving as an intentional exit point for heat and smoke or by already being damaged enough to allow gases to escape.
But there are caveats:
- Acrylic or plastic skylights often melt quickly under high heat. This can result in uncontrolled openings that aren’t on the firefighter’s terms—sometimes too soon, sometimes too late.
- Glass skylights, particularly those with laminated interlayers like PVB, tend to maintain their shape longer, failing more predictably and holding their structure even under duress. This gives firefighters more control.
One ongoing debate is whether a failed skylight feeds oxygen to the fire or facilitates smoke outflow. The reality is nuanced. If the heat pressure inside is high, outflow dominates—pushing smoke and gases out, rather than pulling oxygen in. But if the fire is not yet ventilated and a weak point forms, there is a risk of flashover due to sudden oxygen inflow.
This is why predictability and structural integrity matter just as much as fire-rating labels. The more control firefighters have, the safer the scenario.
Material Comparisons: Glass, Plastic, and Metal Under Fire
Let’s break down how skylight materials respond to fire:
| Material | Fire Behavior | Comments |
| Acrylic / Polycarbonate | Melts quickly, creating unpredictable openings | Fast failure, not ideal in fire-prone zones |
| Tempered Glass | Shatters under high heat; no post-break stability | Can create sharp debris but clears well |
| Laminated Glass with PVB | Holds shape, resists penetration, limits flame spread | Excellent in maintaining barrier; fire-stable under heat |
| Metal Framing (Steel) | High melting point, but transfers heat rapidly | Strong but may distort |
| Aluminum Framing | Lower melting point, but lightweight and corrosion-resistant | May soften under extreme heat, depending on design |
PVB (polyvinyl butyral), used in laminated glass, acts like a glue layer—holding broken glass in place and preventing shards from falling into the structure. It’s also been shown to improve fire performance by delaying complete failure, allowing better control during an emergency.
Beyond the “What-Ifs”: The Value Skylights Provide
Fire safety is a crucial part of any building design, especially in wildfire-prone regions. But too often, conversations about skylights focus only on the “what-ifs”—what if it fails, what if it feeds the fire, what if it melts?
These concerns are valid. But they’re only one side of the story.
- Skylights bring natural light, improving energy efficiency and reducing daytime lighting loads.
- They promote passive ventilation—a significant health and comfort benefit in homes and commercial spaces.
- In fire events, they may offer firefighters a controlled access point or ventilation release, depending on design and material.
Rather than avoiding skylights altogether, we should design them smarter:
- In areas requiring Class A fire-rated assemblies, opt for glass and aluminum skylights, which provide the closest fire performance available in skylight construction.
- Choose laminated glass with PVB interlayers for better performance.
- Consider frame materials that balance strength and thermal behavior.
- Work with code officials to understand compliance, not just fear liability.
Conclusion: Let’s Keep the Conversation Going
Skylights, like any building feature, carry risks and rewards. But when designed thoughtfully—with quality materials and fire behavior in mind—they can be a valuable part of both day-to-day comfort and emergency response. More than just a roof feature, they can become a tool in the hands of those who fight to protect our homes.
As more real-world stories and expert opinions come in, we’ll continue updating this post. If you’re a firefighter, code official, or building professional with insights—we’d love to hear from you.
