Butt joints are challenging to finish because they require that you build a slight, gradual mound to hide the joint. To make the mound subtle enough to go unnoticed, you must feather the joint compound over a wide area. You can also minimize the difficulties of concealing butt joints by using a back blocking technique when hanging the drywall. We’ll show you the best way to finish drywall butt joints, plus provide a few helpful pointers. The first coat, indicated in blue, should be as thin as possible over the tape. If you use fiberglass mesh tape, it’s fine if you still see the texture through the compound. Use the center of this seam as the reference line to feather the second and third coats further outward on the wall. You want to deposit as little compound as possible along the seam. Concentrate on feathering outward from the center. Apply the second coat (white) with a 6-inch knife. Make a 6-inch swipe to both sides of the joint’s centerline. You’ll apply the third coat (coded red) with a 12-inch knife. Feather 8-10 inches outward from the centerline. Editor’s tip: Use the edge of a 12-inch knife to check your progress in tapering a butt joint. With the middle of the blade at the centerline of the seam, an ideal seam will be nearly flat over the full length of the blade. If you see light between the blade and the wall or if the blade rocks more than 1/16 inch in either direction, apply another coat. Again, taper from the centerline toward each side.
