Innovations in drywall finishing

by brittney_cutler_2 | July 11, 2022 8:00 am

[1]

By Michelle Maybee, P.Eng., CTR, and Darlene Helfrich, IDT, CTR

Drywall finishing is an art form. It requires a well-trained and practiced tradesperson as well as the right tools to achieve beautiful, long-lasting results. Drywall finishing sets the tone for the job. If done well, the walls and ceiling will fade into the background. If done poorly, it can become a focal point and detract from the overall project.

Often, contractors are working under extreme conditions and the pressure to finish on time forces them to stretch product performance to the limit. This can lead to problems such as shrinkage, swelling, or cracking and the cost for repairs can be significant. There are areas of concern with finishing which are often overlooked in specification, which can have a significant impact on the overall esthetic of the finished project. Some of these concerns can be solved with advanced products, others with awareness of the jobsite conditions and an understanding of how and when to adjust finishing procedures to make conditions more favourable.

Drywall corners

Drywall corners can be especially difficult to finish and are where most of the day-to-day damage occurs. They are a perfect example of how evolving technology and new products can resolve many issues which may result from the installation of traditional products. ASTM C1047, Standard Specification for Accessories for Gypsum Wallboard and Gypsum Veneer Base[2], sets the minimum standards for accessories like corner beads, but many advanced products exceed those minimum requirements.

Metal corner bead

[3]

Metal corner beads have been the standard choice since their inception. They are inexpensive to manufacture and are widely available; however, they have many challenges. Traditional metal corner beads are installed by nailing or crimping them to the wall studs and finishing with large amounts of joint compound. The metal will follow the edge of the wall instead of floating on the corner, which means the corner may not always be straight.

The metal does not form a strong bond with the joint compound and a significant amount of compound is needed for the installation. Any movement, shrinkage, or impact can lead to cracks and chipping or nail pops and with impact, metal corners will permanently dent. Call backs for jobsite corner repairs are common, and it is often difficult to return the finish to an acceptable condition.

Paper-face metal corner bead

The introduction of paper-faced metal helped eliminate some of the issues associated with early versions of metal corner beads. A thin covering of paper over the metal allows the corner bead to be installed using joint compound rather than mechanical fasteners. With this type of installation, the corner floats straight on the compound, making it easier to finish. These corners, however, are still easy to dent and, therefore, difficult to repair.

Vinyl corner bead

Vinyl or polymer-based corner beads further reduce issues and improve overall results by providing higher durability than metal. They are also available in a variety of different shapes. These corner beads are less susceptible to damage during handling and will not dent like their metal counterparts. Options such as water activated polymer beads go one step further and eliminate the need for staples or added glue, as the adhesive is already applied to the corner. Once it is activated using water, it is ready for installation.

[4]

Laminated polymer corner bead

Laminated co-polymer corner beads are one of the best solutions, as they not only combine high strength and performance but also simple installation to provide one of the toughest, straightest edges.

The corner bead’s polymer core withstands impact and will not dent, and the interior joint tape permanently bonds the corner to the drywall with a small amount of joint compound. Its abuse-resistant surface paper also eliminates cracks, chips and peels, and abrasion, and accepts any traditional finish.

These corner beads are available as pre-cut sticks or flexible roll products which are ideal for off-angle applications, or short and long runs, such as long columns, and bulkheads. The wide flange covers large gaps, compensating for poor framing, while the built-in hinge fits any inside or outside corner angle to create crisp, straight lines.

The material costs associated with advanced corner bead products is higher, but it is a small figure compared to the overall budget. When the cost of installation, repair, and replacement is considered, the material cost becomes insignificant or turns into savings.

Automated equipment

[5]

Installation options and tools have also evolved. Automated equipment is available which increases installation speed, quality, and efficiency. The gold standard of equipment for corners is an automated drywall corner system which will produce a ready-to-install corner, cut to any length or angle, with the correct amount of joint compound applied, resulting in less jobsite waste and faster installation. This automated system is readily available across Canada and the speed and quality of the installation can quickly outweigh any added costs that are incurred.

Application and finishing recommendations for gypsum panel products

Another area of concern which can have a huge impact on the overall esthetic of the project is joint finishing. The Gypsum Association (GA)[6], which is comprised of all active gypsum board manufacturers in North America, is the technical centre for the application, finishing, and overall use of gypsum board products. The association keeps a library of technical publications which are developed and updated through collaboration with its member companies.

The GA-216, Application and Finishing of Gypsum Panel Product, provides the most up-to-date industry recommendations for the proper installation and finishing of drywall, including related accessories. Architects and specifiers consult and reference GA-216 to ensure proper handling and storage on the jobsite, proper installation of boards and control joints; and the proper application of finishing. It provides guidance for metal, plastic, or “other suitable type of corner protection,” permitting standard products and innovative products and systems for corner applications.

[7]

Jobsite conditions

Following industry guidelines and recommendations will make joints disappear behind a smooth, flat surface. One key element to achieve these results is allowing each layer of joint compound to completely dry before starting on the next step. That said, how long it takes for each layer to dry depends on the temperature and relative humidity (RH) levels within the space.

Within GA-216, it is noted “drying-type compounds shall be allowed to dry thoroughly…before sanding or the application of additional coats.” This document also references GA-236, Joint Treatment Under Extreme Weather Conditions, which describes the impact of temperature and RH on joint compound materials and provides guidance on how to minimize potential problems.

Handling joint treatment under extreme weather conditions

The term “extreme weather” in the GA-236 title may be misleading because, in Canada, there are many times of the year where “extreme” conditions exist when talking about drying of joint compound. Progress on the job does not need to stop if the temperature or RH levels are not within the optimal range for proper drying of joint compound. Understanding and adjusting site conditions is possible, but recognizing it needs to be done is the first step.

[8]

A chart and table within GA-236 shows the effect of RH and temperature on drying time for each coat of joint treatment. To achieve the best results, each coat must be allowed to thoroughly dry before applying another coat. Unfavourable temperature and RH conditions may require a drying time of more than three days per coat. It is important to keep in mind that slow or poor drying conditions often result in problems with the final finish.

In hot, dry weather, joint compound dries too quickly. Reducing ventilation is one way to help maintain the indoor humidity level as well as protect wet joints from direct air movement which accelerates drying and can cause fissures and edge cracks.

In wet, humid weather, joint compound dries very slowly. It could take days for each coat to thoroughly dry; therefore, dehumidifiers can be used to improve RH levels and get back into the optimum range for drying.

[9]

In cold weather, heat needs to be provided. It is important to ensure room temperature is kept between 10 and 35 C (50 and 95 F) for 48 hours beforehand, and continuously until materials are completely dry. Heaters should not be allowed to blow directly on wall surfaces as this can result in the compound drying too quickly and causing cracking and localized delamination to occur. Some heaters can also introduce excessive moisture into the air; therefore, RH levels should be monitored, and sufficient ventilation should be provided.

Jobsite monitoring

Some gypsum manufacturers offer installers monitoring services on select projects. By monitoring jobsite conditions using data loggers before, during, and after application, finishing experts can help contractors understand their specific conditions and provide solutions to achieve and maintain optimum drying conditions, preventing many common finishing problems.

Having to repair any finishing problems after the job has been completed is not good for a contractor’s reputation or pocketbook. Renting fans, dehumidifiers, or adding electric heaters is a fraction of the cost; therefore, understanding what optimal conditions should be met and how to maintain them are the keys to success.

Conclusion

[10]

As the tradespeople of yesterday retire and construction schedules are compressed, the industry may not have the same level of artistry in the field or the time for attention to detail; using advanced products and tools can not only help offset these challenges but also ensure high quality, long-term results can still be achieved. Today, the choice of products and an understanding of how to prevent problems can have a major impact on the overall impression of a finished project, as well as how it stands up over time.

Authors

[11]Michelle Maybee, P.Eng., CTR, is an architectural solutions manager for CertainTeed Canada, based in eastern Ontario. She has been in the building products industry for more than 20 years supporting the design community in the province. Maybee is a member of Construction Specifications Canada (CSC), the Gypsum Association (GA), the Building Envelope Council Ottawa Region (BECOR), and the Canadian Green Building Council (CaGBC). She can be reached at michelle.maybee@saint-gobain.com.

[12]Darlene Helfrich, IDT, CTR, has spent more than half her career as a manufacturer’s technical representative. Previously, she spent many years as an interior designer in Edmonton, Alberta, working with a few different architectural firms. Helfrich has been actively involved in the Edmonton Construction Specifications Canada (CSC) chapter for more than 24 years.

Source URL: https://www.constructioncanada.net/innovations-in-drywall-finishing/

---