Finishing - 14044

Builder 3&2 Volume 02 - Construction manual for building structures
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Figure 5-9.—Finishing drywall joints. Applying drywall in older buildings yields a lot of waste because framing is not always standardized. Use the cutoffs in such out-of-the-way places as closets. Don’t piece together small sections in areas where you’ll notice seams. Never assume that ceilings are square with walls. Always measure from at least two points, and cut accordingly. Drywall is quite good for creating or covering curved walls. For the best results, use two layers or 1/4-inch drywall, hung horizontally. The framing members of the curve should be placed at intervals of no more than 16 inches OC; 12 inches is better. For an 8-foot sheet applied horizontally, an arc depth of 2 to 3 feet should be no problem, but do check the manufacturer’s specifications. Sharper curves may require backcutting (scoring slots into the back so that the sheet can be bent easily) or wetting (wet-sponging the front and back of the sheet to soften the gypsum). Results are not always predictable, though. When applying the second layer of 1/4-inch drywall, stagger the vertical butt joints. Finishing The finishing of gypsum board drywall is generally a three-coat application. Attention to drying times between coats prevents rework that has a cost involved as well as extra time. Where sheets of drywall join, the joints are covered with joint tape and compound (fig. 5-9). The procedure is straightforward. 1. 2. 3, Spread a swath of bedding compound about 4 inches wide down the center of the joint (fig. 5-9, view A). Press the tape into the center of the joint with a 6-inch finish knife (fig. 5-9, view B). Apply another coat of compound over the first to bury the tape (fig. 5-9, view C). As you apply the compound over the tape, bear down so you take up any excess. Scrape clean any excess, however, as sanding it off can be tedious. When the first coat is dry, sand the edges with fine-grit sand paper while wearing personal- protective equipment. Using a 12-inch knife, apply a topping of compound 2 to 4 inches wider than the first applications (view D). Sand the second coat of compound when it is dry. Apply the third and final coat, feathering it out another 2 to 3 inches on each side of the joint. You should be able to do this with a 12-inch knife, Otherwise, you should use a 16-inch “feathering trowel.” 5-9

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