Taping: How to Tape Drywall Seams and Corners

Before you start slapping drywall compound on your walls and ceilings, it's helpful to have a clear idea of what you're trying to accomplish with each application. Experienced drywallers produce a smooth surface in three coats, but beginners should prepare themselves for at least four coats.

Drywall compound shrinks as it dries. So even if you achieve a flawless surface off your drywall knife, evaporation will create a depression as the compound dries.

On the first coat, you want to embed the tape at all joints and begin to fill the fastener holes. At outside corners, your goal is to begin a smooth transition from the outside edge onto the surface of the wall.

During the second coat, you'll fill the valley of tapered seams and feather the edges. At butt joints, you'll feather the application outward in both directions from the seam. You'll also widen the application at inside and outside corners. A second coat over fasteners may nearly finish hiding them.

At the third coat, you continue to widen the application at every seam, corner, and over fasteners to create gradual transitions. You'll slightly overfill all areas to compensate for shrinkage and to create a small amount of surplus for sanding to a perfect surface.

Cover the tape with a coat of setting-type or all-purpose compound applied with a 6-inch drywall knife. Lay on enough compound to cover the tape but still permit you to faintly see the texture of the mesh. Avoid the temptation of building a thick coat with this first pass; you'll simply invite cracks as a result of uneven drying.

If you use ready-mixed compound, wait until the first coat dries thoroughly. There's no need to sand between coats of compound. Lightly push the edge of a drywall knife along the wall to knock down ridges or blobs.

The purpose of the second coat is to fill the tapered valley. Use a 10-inch drywall knife, and pull the compound along the seam to deposit material in a swath that matches the width of the knife. Again, avoid laying down too much material.

For the third coat, switch to a 12- to 14-inch knife to complete the filling and to feather the compound onto the drywall. Stick with a 12-inch knife if you're a beginner; the 14-incher requires more skill to control.