Taping: How to Tape Drywall Seams and Corners

Covering Seams and Corners

For tapered seams between two drywall sheets, all you need to do is fill the valley. You should build the thickness in three or more coats. You'll sand the final application to create a flat transition.

Resist the urge to excessively mound up the compound in an effort to speed the job. Instead, count on at least three applications. At that point, carefully check your progress by spanning a drywall knife blade across the joint. Look for daylight between the blade and the compound. If the joint's filled, you're ready to sand. If the blade rocks because the compound's too high, be prepared for a lot of sanding.

Checklist

Time
Project time depends upon your experience level, application care, and size of the room

Tools
Mud tray, drywall knife, utility knife

Skills
Cutting tape, spreading compound

Prep
Compound is mixed and placed into mud pan

Materials
Drywall compound, fiberglass mesh tape

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The Three-Coat System

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.

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Step 1

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.

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Half Full or Half Empty?

Whichever way you prefer to answer the philosophical question, fill your mud tray about halfway. If you're new to drywall, you'll be surprised how quickly a mud tray can seem heavy. There's no need to make the job more difficult than it needs to be by overfilling the tray.

Step 2

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.

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Loading the Knife

Dip your drywall knife into the tray to load it, then scrape the back edge of the knife along the tray's edge to remove compound that clings there. Every few dips, scrape all the compound from the knife so that you don't get a line of compound that starts to dry on the knife. If you notice dried bits, scrape them into a disposal container.

Step 3

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.

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Feather the Edges

Use a light touch when filling fastener holes or you won't leave enough material to allow for the inevitable shrinkage. Think about creating a feathered area all around the fastener's location instead of concentrating on filling only the dimple. A single stroke with a 6-inch knife covers fasteners on all three coats.

Step 4

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.

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Cover Several Holes in One Stroke

You don't have to cover each fastener individually. Draw your knife over a row of fasteners at once and you'll speed your work. You'll also do a better job of disguising the location of the fasteners.

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