Construction Specialties (CS), a leading manufacturer of high-performance architectural building products, introduces a new undermount model to its FB-17 series of expansion joint fire barriers. This line of products effectively minimizes smoke passage while accommodating dynamic movement, without degradation of the material.

The FB-17UM system installs from below the joint instead of from above, as is the normal installation for expansion joints. This makes it ideally suited for applications where access above the joint opening is not possible, including:

• Renovations when a wall cannot be demolished and going under is the only option

• Parking garages or under stadiums, where aesthetics may not primary objectives

• Pre-cast slabs that can’t be cut

• Other areas where an emergency solution is needed

“Construction Specialties developed the industry’s first UL-approved expansion joint fire barrier in 1983, then innovated models as new projects and applications came along,” said Gabriel Blasi, CDT, Director of Engineered Product Solutions for Construction Specialties. “Our new undermount fire barrier emerged directly from a customer need. They encountered a situation where they had a fire-rated joint and couldn’t install fire barrier in the traditional way. We had to find a solution where they could install from below the floor joint.”

The FB-17UM Undermount Expansion Joint Fire Barrier is designed for 5"–20" nominal and 9"–30" maximum floor expansion joints where there are seismic, thermal, or wind-sway design requirements. It has been third-party tested and listed for 2-hour floor endurance rating, meeting UL 2079, ASTM E1966, and ASTM E1399 performance standards.

It is available in 10' (304.8cm) stock lengths and engineered for simple splicing. A lateral slide option accommodates multidirectional movement.

To learn more about the FB-17 series of expansion joint fire barriers, visit