Glass can break in an earthquake even if nothing touches it. The building sways, the window frames bend, and the glass gets squeezed until it cracks. In an office, these are often the panes people sit next to every day: conference room walls, glass partitions, and tall lobby windows. Here is why it happens, which glass to worry about, and what window film can do.
The 2026 Great Washington ShakeOut drill runs on Thursday, October 15, at 10:15 a.m. Organizers ask people to drop, cover, and hold on, then do one more thing to get ready. For offices and schools, we suggest that one more thing be a quick look at the glass.
On February 28, 2001, a magnitude 6.8 earthquake hit the Puget Sound region. The Pacific Northwest Seismic Network (PNSN) says it caused about $2 billion in damage and injured 400 people. Most modern buildings stayed up, but broken windows, fallen ceilings, and damaged pipes disrupted work at Starbucks, Boeing, Amazon, and government offices. PNSN found that this kind of damage, plus lost business, made up most of the cost.
Quakes like Nisqually hit this region about every 30 years. PNSN puts the chance of another one above magnitude 6.0 at 84% in the next 50 years. The state’s ShakeOut organizers add that Washington has the second-highest earthquake risk in the U.S., after California.
In an earthquake, each floor of a building moves a little differently from the floor below. Window frames are attached to both floors, so they lean out of square. The glass inside can’t bend. If the frame leaves no room around the edges, it presses on the glass until it cracks.
The International Window Film Association (IWFA) calls this a racking motion and says it often breaks glass and makes it fall out. FEMA’s earthquake guide (E-74) agrees that glass is most at risk when its frame leaves too little space around it. Nothing has to hit the window. The building’s own movement does the damage.
This is a different kind of break from a rock or a hammer. We explain how film holds glass after a hit in Can a Thin Sheet of Film Really Stop Glass From Flying Everywhere?. In an earthquake, the force comes from the frame, and it keeps coming. The Nisqually shaking lasted more than 30 seconds.
FEMA warns that broken glass walls can drop glass on people and block hallways while everyone is trying to get out. When we walk an office, these are the spots we check first:
If your office has any of these, start there. That is also where film makes the biggest difference.
Glass type matters too. Older walls and windows often use plain glass that breaks into big, sharp pieces. Tempered glass breaks into small, blunt bits, but those bits still fall out of the frame. We compare glass types and films in Security Film vs. Standard Window Tint.
Many installers talk mostly about film thickness. In an earthquake, the bigger question is whether the cracked pane stays in its frame. Film on its own keeps the broken pieces stuck together, but the whole sheet can still slide out of a bent frame.
A 2004 Penn State study tested this. Researchers shook filmed glass in simulated earthquakes and tried three ways of anchoring the film to the frame. The type of anchor changed how soon the glass cracked and whether it fell out. In some tests, whole filmed panes pulled out of their frames.
That is why we recommend anchoring the film to the frame on high-risk glass. 3M makes Impact Protection Attachment (IPA) Sealant for this job and lists earthquakes among its uses. We usually pair it with 3M Scotchshield Safety & Security Ultra film. Some low bids skip the sealant to save money, so ask about it when you compare quotes.
Film helps, but it has limits, and we would rather you know them up front. Here is what it will not do:
What film does well is keep broken glass in place and off the hallway floor. With an attachment, it also helps keep the cracked pane in its frame until someone can replace it.
After the drill, take 20 minutes to walk your floor with a phone. You don’t need any tools. Write down or photograph:
This list shows which glass to fix first, and it gives any installer something specific to quote. Safety markers on glass walls help people see the glass, but they add no strength. We cover them in Distraction Markers for Clear Glass.
If you’d like help with your list, we’ll walk the floor with you for free. We work with offices, schools, and clinics in Seattle, Bellevue, Tukwila, and Renton. We check the glass type, the frames, and which openings need film plus attachment. As a certified 3M dealer, we install both to 3M’s specifications.
Contact D&A Customs to book a time, or read more about our Safety and Security Window Film service. Schools can also see our School Safety page and our guide to federal grants for school safety film.
