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It’s Easy to Work with Thermafiber® TopStop®

Meeting firewall requirements can be complex and time-consuming. Head-of-wall voids must be filled with mineral wool. However, cutting from large batts of insulation on-site takes space, time, and skill. So, Owens Corning® Thermafiber® worked to create a fast and convenient solution to filling voids in head-of-walls. The result is Thermafiber® TopStop®, a pre-cut head-of-wall safing insulation that is easy to work with, meets compression needs, and satisfies fire codes for fire containment in head-of-wall joint constructions. It allows for fast installation, giving site managers and foremen time to move on to other aspects of their builds quickly.

Specially Developed to Fill Headwall Voids

Todd Shear, National Facades Manager at Owens Corning, is an expert on Thermafiber® TopStop®. “I work in Wabash, Indiana, where TopStop® is manufactured. It was created to be a convenience item,” he notes. This product was specially developed to fill head-of-wall voids, often appearing when decking materials cross over interior partition walls. When these gaps exist, the fire code often mandate that they be filled with safing, a mineral wool insulation firestopping product. All Thermafiber® safing firestopping insulation materials are designed to provide enhanced fire protection in floor and wall penetrations when installed to code. However, pre-cut Thermafiber® TopStop® offers a convenient way to meet firewall requirements. It really saves time.”

Six-Pound Density Exceeds Code Requirements

HW (head of wall) code criteria is established by Underwriters Laboratories (UL) tested assemblies. “The criteria includes details on the prescribed material,” says Shear. “So, head of wall void can’t be stuffed with any old mineral wool; it’s got to be the right type of mineral wool, a product called safing that has been tested in the specified assembly.”

He continues, “Code usually only requires a four-pound density, but Thermafiber® TopStop® is a six-pound actual density, which makes it easy for contractors to install the product and meet code for compression. TopStop® is also pre-cut into a trapezoidal shape, which is a time-saving configuration.


Fits Easily in Crowded Job Site

Construction zones in the New York City region can be cramped, so efficient storage at the work site is important. Thermafiber® TopStop® is tightly packed into flat boxes that are easy to transport and easy to stack. “When contractors use TopStop®,” Shear notes, “it keeps the work site tidy. There aren’t a bunch of bags of safing lying around that need to be cut into trapezoidal shapes.” The boxes are also easily recycled.

Eliminates Complicated Cutting


Cutting mineral wool is a process. The coarse fiber is compressed, making it difficult to slice up. The process of customizing mineral wool boards to fit into voids can be complicated. Shear explains, “If workers have to cut the mineral wool to size, they must first lay out the pieces, usually two-foot by four-foot pieces, and this space-consuming activity usually happens at the work site.”

Calculations can also be problematic. “Because this void area is a trapezoidal shape,” says Shear, “and because there’s compression involved, they’re going to need to cut pieces slightly larger than the opening or the void. Mistakes happen. It’s not always efficient, and material gets wasted.”

He adds, “Next, the materials must be cut with a serrated knife, and there must be bevels on each end. And then, the scraps must be gathered up and put with the trash. It’s not fast, and it’s not simple.”

TopStop® Saves Time

Thermafiber® TopStop® reduces a series of problems, making filling head-of-wall flute and top of wall openings a simple, straightforward part of the job. “Workers just pull strips out of the package, ready to go,” Shear notes. “They cut the strips to the desired length and then compress them in the opening. That’s it. There’s minimal waste. And installation can go quickly, usually taking about half the time of cutting roles. So, on a big job, Thermafiber® TopStop® can save days of time.”

TopStop® also makes it easier to pass inspections. “Let’s face it, to an inspector, one type of mineral wool looks a lot like another,” Shear emphasizes. “Once the safing product is out of the package and stuffed into the opening, it’s almost impossible to tell what it is. But with a TopStop® product, just show them the box. From an inspection standpoint, TopStop® is easy to identify and approve.”

Ask Metro Interior Distributors About Thermafiber® TopStop®

Construction jobs are complicated and time-consuming, so when there’s an easy, affordable shortcut, it makes sense to give it every consideration. The team at Metro Interior Distributors are big fans of TopStop®. So don’t hesitate to contact our experienced sales team to discover how TopStop® can help make you and your job fast, easy, and efficient.