structural products

Despite dropping to a 50-year low in 2016, homeownership remains the biggest investment for many Americans. People expect their house, therefore, to keep them safe as long as they live in the structure, especially during extreme weather events like a winter storm or hurricane. Even if owners must evacuate their residence, they anticipate the building will largely stay in one piece.

Structural products such as straps, connectors and fasteners equip a home to survive storms and, increasingly, natural disasters. But they need to have the strength to resist the loads that will be applied to them, provide an easy installation process and be durable enough to perform over the lifetime of the structure. Rigorous testing helps ensure a product meets homeowner expectations.

Qualified Remodeler asked a number of manufacturers about their newest product offerings and how they enable a house to withstand hurricane-force winds. An increase in both the occurrence and magnitude of extreme weather events has compelled many companies to create products that will not only fortify a building against severe storms—but also give its occupants peace of mind.

Recent introductions

Simpson Strong-Tie produces hurricane ties that connect the roof to the top of walls, and its stud plate ties connect top and bottom plates to stud walls. The manufacturer also offers Strong-Drive SDWC Truss and SDWF Floor-to-Floor screw systems, which bind homes together to resist high winds and other uplift forces that could cause structural failure during an extreme weather event.

“The screws are an alternative to hurricane ties and ensure a continuous load path,” says Randy Shackelford, a professional engineer and the manager of codes and standards at Simpson Strong-Tie. “These fasteners are used to connect rafters or trusses to top plates, top plates to studs, studs to bottom plates and also the bottom plates of an upper floor to the top plates of the floor below.”

Two new foundation plates—URFP and FRFP—retrofit the connections between an older house and its substructure to bolster the building against earthquakes, Shackelford adds. The company also manufactures several types of anchors, such as the Titen HD post-installed screw anchor or the MASA embedded anchor, that connect the bottom plate of a wall to the concrete foundation.

MiTek developed two new products, the Hardy Frame Cold-Formed Steel Moments Frame and the DamperFrame, to help protect homes from powerful lateral forces. The Cold-Formed Steel Moments Frame provides high lateral-load resistance in narrow spaces around window or door openings, while the DamperFrame offers shock absorption through its lateral energy dissipation.

“Hurricanes bring a number of risks to buildings,” says Jesse Karns, a professional and structural engineer as well as the director of engineering, lateral systems, at MiTek. “High winds can work to laterally destabilize a building; suction forces induced by high winds may attempt to lift and separate the roof from the structure; and flooding or storm surge can induce large lateral forces.”

Other products from MiTek, including its Z4 Tie-Down System and USP wood connectors, have been effective in holding a house together, he adds. They strengthen the resistance to wind uplift forces on a roof, minimizing the damage from a hurricane or another extreme weather event. “It is important to have a full range of building products that can address these hazards,” Karns says.

FastenMaster recently innovated with its FrameFAST System, a screw and driver tool that—when all the connections are made—gives a structure a continuous load path with a single fastener type. The FrameFAST System facilitates the connection between the truss and top plate, stud to top plate, stud to bottom plate and plate to rim on down, explains Mark Dicaire, technical manager at FastenMaster.

“In areas that are prone to severe weather, ensuring the structure is securely fastened all the way to the foundation is critical,” he adds. “FrameFAST boasts increased uplift values [compared to] standard methods—with the simplicity of one fastener and a fast, easy-to-use [installation] tool.”

Product evolutions

Earlier this fall, Simpson Strong-Tie introduced a high-performance brick tie that establishes a connection between a wood structure and a brick façade. The basic corrugated brick tie has some limitations in use—the brick veneer must be 1 inch or less away from the wall—so the company developed a stronger sheet metal brick tie that can bridge gaps up to 3 inches, Shackelford notes.

“Newer construction, with mixtures of stone or other materials with standard brick, often results in airspaces greater than 1 inch,” he says. Simpson Strong-Tie also launched its PSQ pile strap, a straight tie designed for homes raised on pilings. The PSQ reinforces the connection between the beam and the piling, and it makes installation easy because the strap uses screws instead of bolts.

Technology plays a few essential roles in the company being able to manufacture more disaster-resistant products, Shackelford explains. “First, we use technology in the product development process to be able to model on a computer how a product might perform under actual loading,” he says. “That way we can design it virtually before we fabricate a prototype for physical testing.

“We [also] use technology in the manufacture of our products—from quality control procedures that allow us to track a product from the time the raw material comes in until the time it is sold, to the use of specialized manufacturing machines that can use a laser to cut the metal for a part and then automatically punch all the holes [in that part] in the proper places,” Shackelford adds.

Simpson Strong-Tie has a main component test lab at its headquarters in Pleasanton, California, and employs component test labs in its factories throughout the country. The manufacturer also operates a state-of-the-art system testing facility in Stockton, California, where workers can test entire structural systems and examine how Simpson products perform in a whole-house setting.

“We test our products in the same manner that they would be installed in the field—pulling and pushing on them until they break so that we know their ultimate strength,” Shackelford explains. “Then we apply a safety factor as required by the building to allow for things like variability of wood and [oversight]. That way, we know the product will always perform better than required.”

MiTek uses a combination of full-scale physical testing and high-tech virtual testing—computer simulations with physics-based finite-element modeling (FEM)—to develop products and ensure they will perform as needed under extreme weather events and conditions, Karns notes. Building code standards usually define the physical testing requirements for many product types, he adds.

“These requirements attempt to replicate the most relevant ‘real world’ conditions expected for the product type and the hazard, but may not address every possible scenario,” he says. “MiTek looks beyond the required testing to test products for scenarios that are deemed critical to ensure the product’s performance. To validate the product performance observed under physical testing and to look beyond the confines of the tests, MiTek puts its products through multiple alternative loading and detailing conditions with extensive use of FEM computer simulations.”

Future considerations

FastenMaster pays close attention to the steel the company deploys, specifically the heat-treating and coating processes, to construct a durable and dependable fastener for use in extreme weather conditions, Dicaire says. The manufacturer tests all of its products in-house during development, followed by an accredited ANSI 17065 testing facility and a third-party quality control program.

“It’s unique to be a domestic manufacturer, where we can control the quality of our products and all of the manufacturing processes—including the complex heat-treat requirements and stringent coatings,” Dicaire explains. “We have also invested in an in-house research and development facility where we utilize high-tech testing equipment in our development of new and innovative products.”

In 2019, FastenMaster will launch a new head attachment for its FrameFAST System that allows an installer to make the stud-to-plate connection with a single screw—and without the need for a ladder—in order to establish a continuous load path quickly, accurately and safely, Dicaire notes.

MiTek says multifamily residential construction would open up significant opportunities and will be sorely needed to effectively reduce the dearth of housing in many areas of the country. Its new lateral-force-resisting products are designed to increase safety in multifamily buildings, Karns says.

“To ensure public safety and reduce the economic impact of extreme weather, it is important that building products be able to perform under these conditions,” he adds. “It is also important these products are able to endure the environmental conditions of the area, and for the expected life of the building, so they will be there when needed to resist a hurricane or another extreme hazard.”

Simpson Strong-Tie has focused on the opportunity in cross-laminated timber (CLT), which has become more popular as a method for designing and constructing large wood buildings; but the company will continue to develop new products to meet customer needs and make construction more economical, Shackelford says.

“We intend to see what can be learned from the storms that occurred this year by sending our engineers to evaluate the damage firsthand, and also by reading reports from various industry and university groups to take in their insights,” he adds. | QR

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