If You Can't Take the Heat - FB 17UM Can

Fire barrier expansion joint systems are necessary to help maintain a building’s safety, resiliency, and structural integrity because they work to block the passage of fire and smoke from permeating expansion joint gaps and traveling through the building.


Sounds pretty important, right? But what happens when the usual method of installation isn’t possible? Typically, these systems are installed from above the joint. Sometimes, though, there’s no accessibility from the top side. In those cases, installing from below can be the answer.


FB-17UM is the newest addition to our FB-17 fire barrier line, and it’s used to help fire rate an expansion joint opening from the underside. This undermount barrier application has been tested to provide a 2-hour fire endurance rating, and it’s great for when installing from above the joint is difficult or impossiblelike where there is an existing shaft wall or perhaps during a renovation when the only access available is from the underside of the slab. It’s also a good choice in spaces like parking garages or under stadiums, where design aesthetics might not be a primary concern.


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One of the things we love about the FB-17 series is that these barriers accommodate dynamic movement without degradation of the material, and the new undermount application is no different. Designed for 5”-20” nominal and 9”-30” maximum floor expansion joints where there are seismic, thermal, and/or wind sway requirements, FB-17UM is offered in both a standard version and a lateral shear version. The lateral shear version has a lateral slide track that allows the barrier to slip independently of the building; one side is fixed to the building while the other side has the ability to slide.


Like many of our products, FB-17UM is the direct result of a customer need, and this fire barrier takes the heat so the rest of your building might avoid it. You can learn more about the FB-17 series here on our website, but don’t just take our word for it— Building Design + Construction named FB-17UM one of its top building products of August 2023, and Building Enclosure and retrofit also did write-ups that we think you’ll find interesting.

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