If the corner bead is not installed properly, it is almost impossible to correct the problem with the joint compound. To get a professional looking corner you need to follow some simple rules, but if the framing is damaged, warped, or not installed properly the corner bead will not turn out right. Fastening corner bead to the drywall can be done with basic tools or with a special corner bead crimping tool.
One of the trickiest jobs in home improvement is installing drywall corner bead. Unless you have been show how to correctly install corner bead, or you have years of practice, it can make an otherwise good drywall job look sloppy and unprofessional. While many do it yourselfers focus on the corner bead itself, many of the problems stem from improper drywall installation.
Many homeowners assume that corner bead is only installed on outside corners or walls, but drywall corner bead is also found around windows, support beams, soffits, and the openings between rooms.
Without straight framing members it is almost impossible to create a smooth and sharp corner. Warped, twisted or bowed studs will cause the drywall to be crooked after it is hung. The drywall corner bead will not lay flat and you will have a tough time applying the finish coats of joint compound.
If at all possible, cut away the drywall to determine the condition of the framing behind the wall. It may be that the studs were nailed together or to the sole and top plates incorrectly. It may be possible to remove the fasteners and nail or screw the stud back into place or replace the stud with a new one.
Correct framing of corners
It is difficult to secure corner bead to the ends of studs. Also the framing can be out of line.
Straight soffit framing
Installing drywall on corners
It is important that drywall does not stick out past the corner of walls or soffits; in fact many professional installers hold the sheet back about ¼-inch since the corner bead will cover the gap.
When cutting the drywall make sure that you cut all the way through to prevent a rough edge or use a drywall rasp to smooth the edge. The rough edges will prevent the corner bead from laying flat on the face of the drywall.
Never place the tapered factory edge on either side of an outside corner. While you might think this would make taping the outside corner easier, it is more difficult as the corner would need to be built up with spackle and would lead to cracking in the future.
Installing Corner Bead
The purpose of the corner bead is to protect the drywall edges from damage. Originally all corner beads were metal, but there are also PVC versions that work just as well.
The drywall bead is attached over the drywall and screwed or nailed into the studs but there is also a tool used in commercial applications that cuts into the edges of the corner bead and sticks into the drywall called a clinch-on tool. A frequent problem with using drywall screws is that they protrude past the edge of the metal corner bead or they cause the flange to become wavy or buckle. It is actually easier to use drywall nails to attach the metal corner bead rather than screws because the head of the nail is very thin and will sit flush against the metal bead.
Use caution when nailing so you do not hit the corner of the bead. Dents will be very difficult to spackle over and produce a straight edge. Also metal corner bead can be bent and twisted out of shape very easily and it can also cut your hands with its thin edges.
Drywall corner bead installation tools can be purchased or rented. A clinch-on tool uses no fasteners, but the head of the tool is hit with a rubber mallet to secure the corner bead to the wall.
Do not try to open up the corner bead to a 90 degree angle. The flanges are actually less than 90 degrees and spreading it out can cause the edge of the corner bead to stick out past the corner and show up as a faint crack when finish sanding is completed. An advantage to using a clinch-on tool is that it aligns the corner bead against the corner of the drywall.
Fasten the corner bead from one end to the other on both sides; never nail one side and then the other side. If you nail one side completely before you nail the other side the metal corner bead will most likely twist out of position. When nailing, many professionals start in the middle of the bead and then work to one end and then from the middle to the other end. Space the nails or screws about every 8 to 10 inches.
After the corner bead is secured you should be able to slide the blade of a 6 inch drywall knife over the surface of the bubble of the metal corner bead and adjacent drywall without hitting the head of any fastener or the edge of the metal corner bead.
There are times when two or more pieces of corner bead needs to be installed such as with long soffits or beams. Some people choose to overlap corner bead, but it is often easier to butt the edges together and align the corner. Overlapping corner bead or placing a short piece beneath the lengths, called bridging, of corner bead will cause a bulge and will show up when finished. After butting the corner bead together you can use fiberglass mesh tape to cover the seam and reduce cracking.