Will Safety Film Keep Broken Glass in the Frame During a Seattle Earthquake? How the Edge Attachment Changes the Answer

The Great Washington ShakeOut drill runs on the third Thursday of every October, and this year that was October 15. Drills teach people what to do when the shaking starts. They say nothing about how the glass over a desk or a hallway is held in its frame. If you are weighing earthquake window film for a Seattle office, school or clinic, that question matters more than which film you pick.

The Earthquake Puget Sound Is Most Likely to Get

The quake most likely to hit Puget Sound is not the Cascadia “Big One.” As of 2025, the U.S. Geological Survey puts the 50-year odds of a deep M6.5+ quake in the region at 85%, Washington DNR reports. The same forecast gives a shallow crustal quake of that size a 17% chance and a magnitude 9 megathrust 15%. The 2001 Nisqually quake was a deep one.

Seattle’s Office of Emergency Management lists deep quakes above M6.0 in 1909, 1939, 1946, 1949, 1965 and 2001. It estimates one about every 30 to 50 years. That is the time frame we keep in mind when building owners ask whether seismic film is worth planning for.

Three Ways to Install Safety Film, and Why It Matters in a Quake

Safety film holds a broken pane together. In a quake, the real question is whether that sheet of cracked, filmed glass stays in the opening. The answer depends on how the film meets the frame. Installers use one of three methods:

The difference between these three shows up only after the glass breaks. Each one is explained below.

Daylight Installs Can Drop the Whole Sheet

Madico does not recommend a plain daylight install of safety film. In this method, the film covers only the visible glass and stops short of the frame. Madico warns that once the glass breaks, vibration can shake the entire filmed sheet out of the opening. When we walk a building that already has safety film, the edge detail is one of the first things we check.

Wet Glaze: The Common Choice for Seattle Frames

3M describes its Impact Protection Attachment (IPA) Sealant as a wet glaze that anchors the film to the frame. Seismic events are on its list of uses. Madico says wet glaze is the most common attachment, because many frames don’t allow screws. It also notes the bead must be sized to carry the weight of the whole glazing unit.

Wet glaze needs time to set. 3M’s flyer lists a cure time of 7 to 14 days. Full adhesion takes more than 14 days for a 3/8-inch bead at 77°F and 50% humidity. So we tell clients the edge reaches full strength about two weeks after install, not on install day.

Mechanical and Profile Systems for a Finished Edge

Mechanical systems add a strip that ties film and frame together. Madico calls its screw-and-extrusion system, FrameGard, the safest option and says it is tested to hold 500 to 800 pounds per linear foot. 3M’s Impact Protection Profile skips the screws. It is a flexible, gasket-style strip that bonds film and frame with 3M VHB tape and gives the window a clean, finished look.

Screws are not always an option. A lease, a historic frame or a thin aluminum mullion can rule them out. In those buildings, a bonded profile or a wet glaze bead does the job instead.

How We Pick the Attachment for a Building

Madico puts the rule simply: the right system depends on the weight of the glass and the type of frame. We start there. We also check whether the lease allows drilling, whether a lobby needs a finished edge, and whether the frame itself is sound.

The frame matters as much as the film. On its Scotchshield Ultra Series page, 3M lists the quality of window and door frames among the factors behind seismic damage. A weak or corroded frame can’t hold a pane, however well the film is bonded to it. When we find frames like that, we note it in writing and point the owner to a glazing contractor.

Here is one of our own jobs. At the King County Courthouse in downtown Seattle, we applied 14-mil safety film to the first- and second-floor windows, including the main entrances. We ran Dow Corning 995 structural silicone around the edges to tie the film to the frame. That project was planned for security, but it uses the same type of edge attachment a seismic job calls for.

Where Film Stops and Retrofit Starts

3M is direct about limits. Its Ultra Series page says its films do not prevent property damage, injury or death. Film and attachment also don’t make the building stronger. Washington DNR points to seismic retrofits as the way to cut damage and casualties, and film doesn’t replace one. Its job is smaller: keep broken glass in the frame and off the people below it.

Five Questions to Ask Before You Sign a Safety Film Quote

A quote for earthquake window film should cover more than film thickness. Before you sign, ask the installer, including us, these five questions:

1. Which attachment method is in the scope for each opening: daylight, wet glaze or profile?
2. Is the sealant or profile approved by the film maker, and does the same warranty cover film and edge?
3. How was the bead or profile sized for the weight of each pane?
4. How long until the edge reaches full strength?
5. Which openings did you leave out, and why?

Clear written answers make two quotes easy to compare. If a quote says nothing about the edge, treat it as a daylight install until the installer tells you otherwise.

Book a Seismic Glass Assessment

We walk the glass with you, check frames and edges, and recommend an attachment method for each opening in writing. We work with offices, schools and clinics in Seattle, Bellevue, Tacoma and Tukwila. You can read more about our safety and security window film and school safety work. Or see how we check film-to-glass compatibility before every quote.

Contact us to set up a walk-through after this year’s ShakeOut.