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Author: Stephen Reynolds In certain high-flow applications, abuse-resistant gypsum board can be used as a cost-effective alternative to concrete block units (CMU). These drywall products can contain specially designed glass fiber reinforced materials that can resist hard impact and penetration, contributing to the overall durability and service life of the building's internal space.

Abuse prevention walls are suitable for schools, hospitals, hotels, and apartments-almost any space where you may encounter less gentle brushes and occupants. For areas with heavy traffic or where large and heavy equipment passes, the use of anti-abuse materials can help reduce the number of bruises exposed on the interior walls. Unfortunately, corner beads are often excluded from the specification equation. Without suitable corner beads, the expected impact wall components have inherent defects and their integrity will be reduced.

When the choice of corner beads is determined by the installer, why bother to specify the abuse-resistant plasterboard? Architects know that the quality of gypsum board is judged by the details of its corners. Are they at an acute angle of 90 degrees? Are they cracked? The corner is not only the first thing people notice in the room, but it is also notorious for being the first problematic element in wall assembly. To make matters worse, their repairs are expensive, laborious, and frustrating for owners and installers. Failed corners will leave an impression of failure in the original design and construction of the building.

With only a small investment in high-quality corner beads (a few cents per square foot), you can get a huge return through cleaner design and long-lasting performance. However, it is still necessary to know which corner beads are suitable for the job.

Since corner beads are aesthetic non-structural components of the entire wall system, building codes do not require them to meet specific standards. The specification decision boils down to ease of installation and material quality. A suitable corner bead is one that the craftsman can easily manipulate and install in a precise manner. It should be important to installers, building owners and design professionals.

Metal corner beads Corner beads are an important part of the wall system, because structurally speaking, the corner is the place where most of the damage to the dry wall occurs. The first attempt at reinforcement was metal corner beads. This solution was introduced more than 60 years ago. Due to its low upfront cost and high familiarity, it is still an essential tool for installers.

The disadvantage may be the nature of the material itself. The installation method of metal corner beads is to nail or crimp them to the wall nails, and then use a large amount of jointing agent for finishing. Unfortunately, if there is no seam tape or paper finish, the metal corner beads will not form a strong bond with the seam compound or the wall. In the case of foundation movement, impact or dowel shrinkage, the metal reinforcement is unlikely to resist this stress.

This movement can cause the dry cement to crack along the edges of beads or nails that burst. Due to the strong impact on some corners, metal corner beads often appear dents, which can damage the drywall finish. Unsurprisingly, for projects that use traditional bare metal corner beads for reinforcement, it is common for installers to return to the site for corner repairs.

Paper metal corner beads Paper metal corner beads are a step in the right direction, because they can help installers solve these problems. The paper metal corner bead is similar to its predecessor, pure metal, but the paper surface makes the surface of the corner bead smooth underneath. The paper is treated to withstand severe sanding to improve aesthetics.

These paper metal corner beads can be smeared on the outside of the wall panel surface with a joint agent or the corner beads can be passed through a hopper. Gluing is done on the surface of the paper, so when something hits it, the corners are less likely to crack at the edges. However, if it is hit enough, it will still dent. Paper metal corner beads look cleaner and easier to use.

Paper Copolymer Corner Beads and other paper corner bead products help produce stronger and more flexible corners through a proprietary copolymer configuration. The latest generation of corner beads, they complement more and more designated high-quality high-performance gypsum boards. These corner beads have a factory-applied paper coating for paper seaming tape to strengthen adhesion to the wall to prevent edge cracking. Although they use the same tools and techniques as other beads, they tend to be more user-friendly and require less filler material.

Copolymer materials also have the advantage of "muscle memory". In other words, these corner beads can bounce back from daily impacts, and the metal will absorb the impact and create cracks or dents.

Although corner beads were omitted from the specification requirements, Structus Building Technologies has independently tested copolymer products to more clearly define their impact resistance. In the company's own test, a 1.8 m (6 ft) long galvanized metal corner bead was nailed through a 13 mm (½ inch) gypsum board to a 51 x 102 mm (2 x 4 inch) wooden peg. According to The manufacturer recommends that the corner beads are coated with a general compound and allowed to dry for 72 hours.

The 1.8-meter-long copolymer corner beads are also used in the same types of drywall and dowels. Installed according to the manufacturer's recommendation, the corner beads are coated with general compound and allowed to dry for more than 72 hours. Then drop a 2.3 kg (5 lb) steel weight from different heights directly onto the apex of each specimen to determine the resistance of each installation angle.

At 305 mm (12 inches), an edge crack approximately 76 mm (3 inches) long can be seen on one side of the metal fillet electrode. At 457 mm (18 inches), edge cracks of the same length can be seen on both sides. On the other hand, when the steel weight dropped from 305 mm and 457 mm, or even 610 mm (24 inches), the copolymer angle steel bars were not significantly damaged. At 762 mm (30 inches), there is a slight dent at the apex of the corner.

This independent test can provide insight into the structural differences between metal and copolymer corner bead options. Anecdotal evidence from installers and owners also supports these findings.

Copolymer product options Of course, nothing is one-size-fits-all, so the manufacturer offers a variety of paper-copolymer corner beads options. Although it may be sufficient to specify the paper copolymer as the corner bead style required for the project, it may be more specific.

The three options that many artisans are familiar with are mud-coating, water-activated self-adhesive, and mud-coated flexible copolymer corner beads. The cost of the three is roughly the same, but it may be two to three times the price of a bare metal, depending on the region. However, beads make up a small percentage of the total drywall component cost, and they are not even a rounding error of the total. When labor and warranty costs are included, they may be lower than other technologies.

Mud-coated paper copolymer corner beads use a continuous layer of joint compound to adhere the corner beads to the gypsum board to form a firmer, more straight angle that resists the pressure of normal building movement and impact. Some of the most effective products used in this application include copolymer cores laminated with paper.

Mud and paper metal corner beads are more common, but compared to metal cores, copolymer cores have higher impact resistance and straighter lines-they will not dent or break. Therefore, although mud-coated metal corner beads can certainly minimize edge cracks, copolymer corner beads can actually eliminate this problem. In addition, the copolymer corner beads only need enough cement to bond and feather the edges, which saves a lot of installation time because of less mud coating and faster drying time before they can enter the painting stage.

Water-activated self-adhesive copolymer corner beads. These easy-to-install corner beads have a paper-coated copolymer core and are treated with a strong water-activated adhesive, just like the seal of an envelope. Using this adhesive, the corner beads can quickly form a strong bond with the gypsum board, and the joint can be applied in 30 minutes or less. Their high bond strength and sturdy paper-plastic-paper design provide strong protection against edge cracking, blistering and blistering.

Mud-coated flexible copolymer corner beads sometimes require more flexible corner beads to provide seamless, elastic reinforcement along longer and more challenging angles in the wall. Flexible corner rollers usually have a copolymer or polyvinyl chloride (PVC) core that conforms to all inner and outer corners and forms a clear straight line. Therefore, it is particularly suitable for bevel, cathedral ceiling and partition applications.

Like all mud-coated beads, these flexible copolymer corner beads adhere to the wall through a joint compound. Because they can be easily adjusted to all angles, flexible angle beads do not require multi-angle rods and joints during long-term operation.

Conclusion Buildings designed for long-term beauty include strong and beautiful wall systems. Such walls require strong corner beads for structural reinforcement and clean lines throughout the room. High-performance paper corner beads are suitable materials to achieve these goals and should be included in the project specifications.

Although compared with traditional metals, the upfront cost is higher, but relative to the overall budget, this is a small number. It will also ultimately save money on cracked and scratched corners, and will help enhance the feeling that the building is well-structured and well-designed.

Abuse-resistant plasterboard provides a more sustainable and durable interior for the 47-year-old multi-purpose stadium Leopold-Drolet de Sherbrooke. The recently completed renovation is the first project in Quebec to use this special wall material. It also actively removes indoor circulating volatile organic compounds (VOC) and traps them in the panels.

"Considering the large crowd and level of activity in the arena, this is an ideal product choice," said Nicolas Bilodeau of Bilodeau Baril Associés Architectes. "Sustainability goals are important, but we must also ensure that the specified plaster meets the performance requirements of the design."

Construction Guy Sebas Inc., the general contractor of the project, used approximately 1,600 panels to install most of the interior space of the building that can accommodate more than 5,000 people.

“This project is progressing smoothly because the installer does not need to glaze or degrease the coating with the precast mixture before application, which saves labor costs,” said Pierre Lemay, the company’s principal.

The newly remodeled arena is now the home of Sherbrooke Phoenix, the newest team of the Quebec Major Youth Hockey League. In order to better accommodate the team, the renovation also includes the addition of 32 luxury boxes, 18 galleries, and the addition of ordinary seats, for a total of 4328 seats. Terraces have also been built and the concession area has been renovated. The work was completed last summer, and Phoenix played their first game in August.

Stephen Reynolds is the marketing and business development manager of CertainTeed Gypsum. He holds an MBA degree from Wilfrid Laurier University (Waterloo, Ontario). Reynolds started as a contractor and has been in the construction industry for more than 25 years. You can contact him by email at stephen.reynolds@saint-gobain.com.

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