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Reducing Drywall Callbacks -

Continued On ceilings, place the first screw 7 to 12 inches from the corner along the perimeter of the ceiling. The upper wall panel will support the edge of the ceiling. Screw the upper edge of the top wall panel in place 8 to 12 inches down from the ceiling to avoid fastening to the top plate, where settling may occur. To create a floating corner at a wall intersection, omit fasteners in the corner on the first panel installed. Make sure that the panel edge is supported by proper corner framing, but do not fasten it. Next, install and fasten the abutting corner panel. When taped, the unfastened panel edge will stay secured to the abutting panel, even if the framing pulls away slightly. Screw the remaining ceiling and wall areas using standard fastening procedures. Drywall clips. I usually rely on the screw method to make a floating corner, unless there's a framing element missing, in which case I'll resort to clips — I keep a supply handy in my truck. Drywall clips can be used at inside corners to create an equally effective version of the floating corner, while eliminating the need for a third stud on an inside corner or backup framing along ceiling edges (Figure 3). If you use clips on the ceiling-to-wall juncture, the first screws in the ceiling can be kept back 18 inches from the edge.


Figure 3. Drywall clips, installed about 12 inches apart, offer an alternative approach to floating corners and eliminate the need for the third corner stud or backup framing along ceiling edges.

Using Adhesive

It takes a lot of fasteners to attach the panels to a ceiling or wall. One way to cut down on the number of fasteners is to secure the drywall with an approved ASTM C557 standard drywall adhesive. Application with adhesive is becoming more common — I use it routinely and highly recommend it. By using an adhesive, the number of fasteners needed can be reduced by up to 75 percent. An added benefit is that the adhesive will help to unify and strengthen the structure by increasing the panel's tensile strength by up to 100 percent and its shear strength by up to 50 percent. When using adhesive, apply a 3/8-inch-wide bead to each framing member to within 6 inches of the edge of the drywall. Install fasteners on 16-inch centers along the perimeter of each panel immediately after hanging it. If your fastening schedule is subject to inspection, it's a good idea to let the inspector know beforehand that you'll be using adhesive so that he can schedule an inspection in progress. Otherwise, take photos to back up your assertions.Figure 4. When gluing drywall, it's helpful to stack it overnight to create a slight bow (top). When attached at the perimeter, the curve forces the center of the panel tight against the framing, eliminating the need for temporary fasteners.Panel orientation. When hanging walls, I prefer to hang the drywall horizontally, because it unites more studs at a time, adding bracing strength. Horizontal seams are also less obvious in strong light, and when a seam runs perpendicular to the framing, it flows over any misaligned or bowed studs and helps to hide these imperfections. Problems with Taped Seams When taping drywall seams, the air, surface, and compound temperature should be at least 55°F, with 65°F to 70°F being ideal. It's a good idea to establish the ideal temperature at least a few days before the drywall hanging starts. Once the hanging and taping are underway, maintain a constant temperature — don't work in 80°F weather during the day, then let the temperature drop to 45°F at night. The drywall phase is an important part of the job, so don't try to save a few dollars on heat. In addition, provide adequate ventilation and airflow to help remove excess moisture. Cold and damp weather will adversely affect the taping job, delaying drying times and possibly softening the panels, but hot and dry weather can cause problems, too. Heat can affect the joint tape bond. Hot, dry weather hastens drying, which can result in poor bonding of the tape, edge cracking, and excessive shrinkage of compound. So take some precautions in hot and dry conditions. Eliminate drafts, work shorter joint lengths, use faster setting compounds, and don't weaken the compound by adding excess water. Appropriate compounds. Premixed all-purpose joint compound is very common and convenient to use for all three coats of the taping process, but it doesn't have the same strength, bonding qualities, or stability that a dedicated taping and topping compound combination has. The first coat of the taping process is the tape-embedding coat. It's the most important coat because it is the one from which the joint derives its strength. When dry, the taped joint should be as strong as the drywall panel itself, or normal structural movement may cause joint cracking. I strongly recommend using a tape-embedding compound for the first coat. Look for compounds specifically made for this purpose — it should say so right on the product label. Other compounds are made for topping and finish coats. An all-purpose compound is acceptable for embedding use. I usually work with USG joint compounds; they're consistent, workable, and readily available. Paper tape is stronger than fiberglass mesh tape. It resists stretching, wrinkling, and other distortions during normal structural movement. Fiberglass mesh tape is subject to stretching and is more likely to crack along seams during normal structural movement, so it should be embedded in a setting-type compound to give it added strength. Recently, improvements have been made to mesh tape, making it less likely to stretch and crack. However, it's still best to use a setting-type compound with any mesh tape for the embedding coat. Butted seams. The long edges of a drywall panel are tapered to allow for some tape and compound buildup without creating a visible ridge, but the butted ends are square. To reduce the appearance of butt-ridging, keep butted seams to a minimum by using the longest panels available. Keep the butt joint stable by carefully centering it on the framing member, and use screws, rather than nails, to attach the panels. Sometimes I'll cut a V-groove along the butted seam to remove loose or torn paper facing and allow a deeper seam fill. Visible butt joints in ceilings can be particularly troublesome. I know it's not done in many parts of the country, but it's common in much of the East Coast area to install 1x3 furring, also known as strapping, on 16-inch centers, perpendicular to the ceiling joists before hanging the drywall. The drywall sheets are normally hung with the long edge parallel to the joists and perpendicular to the furring. Furring improves the stability of the drywall panels by bridging irregularities and canceling out movement between joists, and it provides a wider surface to center panel butts on. A trick some builders use is to insert a ripping of 5/8 plywood to fur where the butt joints will fall. The plywood is about 1/8 inch thinner than the 1x3, enabling the drywall to be slightly recessed at the butt. During finishing, the joint can be taped and tooled flush with the surrounding surface, rather than creating a raised seam.