Making the joints in freshly hung drywall disappear behind a smooth, flawless taping job will try your patience. Many problems—slow-drying taping compound, crushed drywall edges and protruding screwheads—interrupt the smooth, efficient flow of your work. Other little problems—scuff marks, dips and ridges—won’t show up until the dust clears and you prime the walls with drywall primer. Going back to fix stuff is time-consuming and a lot of fuss.
Resist the temptation to lower your quality standards. In this story, we’ll demonstrate tips and techniques that pros use to avoid the most irritating slow-ups and flaws. We show these tips roughly in the order you’d use them—drywall prep, selecting your materials, applying the tape and three coats of compound, and sanding to finish up. The pros we interviewed stressed a methodical approach; if you skip a step, chances are you’ll lose time later. Although you won’t be able to work with the speed and dexterity of a pro, these tips will make your drywall taping go faster, and it’ll look better for even the most inexperienced hand.
NOTE: We used water-resistant drywall for visual contrast—the taped seams and strips are easier to see against its green color. Don’t use water-resistant drywall on ceilings (it sags). Also, check with a building inspector; many areas do not permit its use on exterior house walls.
Prime rough and torn areas to consolidate loose paper fibers and seal in chemicals that can bleed through and stain the finish coat of paint. (KILZ and BIN are two common brands available at paint stores.) Ventilate the room well and wear a vapor-absorbing painter’s mask when using solvent-based primers.
Leave a 1/8-in. gap along each flange as a pocket for drywall compound. You should be able to run your taping knife along the bead and the drywall surface without hitting a nailhead or scraping against the flanges. Use a single length of bead for each corner. Otherwise, you’ll get a bump or crease where two pieces join.
Setting compound, unlike regular compound, hardens rapidly and doesn’t shrink. You can begin your taping as soon as it hardens. You buy it powdered and mix it with water. It’s available with a 20-, 45- or 90-minute hardening time from most stores that sell drywall materials. Be sure to buy the sandable variety. Avoid the 20-minute stuff; it’ll harden in your pan.
Fill any gaps larger than 1/8 in. Shut off the electrical power at your main service panel first, before pulling out electrical switches or receptacles to fill around their plaster ears. Make sure the power is off by touching the neutral and hot wires with a voltage tester. More than one pro has spot-welded a taping knife to a hot wire!
Start cleanup before the setting-type compound begins to harden. Leftover compound will catalyze and harden the next batch rapidly, before you can spread it. Heat also accelerates hardening, so on warm days mix the compound with cool water. Dump the leftover mud in a bucket, not down the sink, where it can harden and clog the drain.
Stir with your taping knife until it’s smooth and creamy. It comes lumpy and stiff from the typical 5-gal. pail. If necessary, add water to thin it so it flows better off your knife. Apply the first coat of mud and tape to cover the joints, then two additional coats to smooth the joints. Buy the “lightweight” all-purpose compound because it shrinks less.
Tape troublesome butt joints by embedding your tape in a thin first coat, about 1/8 in. thick, that you partially squish out when you apply the tape (see Fig. A). After it dries, draw a second, third and even a fourth coat well out to each side of the joint to hide the ridge. Make each coat smooth and flat by running one end of a 12-in. knife along the tape and the other end along the drywall. (Many pros prefer using a 12-in. drywall trowel like we show here.) Check your progress by placing a 4-ft. straightedge on the wall across the joint. Hiding a butt joint takes patience!
Figure A: Tapered and Butt Joints
Tapered joints are easy to cover because the two tapered edges of each sheet of drywall leave a pocket that you fill with drywall tape and compound. Butt joints, the non-tapered ends of drywall sheets, are difficult to hide because the tape protrudes above the wall surface. Pros avoid butt joints by installing longer sheets of drywall that reach from corner to corner.