How to Install Drywall Corner Bead
For standard 90 degree angles, are the following installation options that are common throughout drywall on most homes.
Metal - Outside Corners
1) Cut with snips to fit (aircraft shears cut clean with little buckle) and set the bead progressing in a single direction with nails, although screws may be used for a tighter cinch. Be aware that fastening too tight can cause cracking.
2) As an optional method before fastening the bead - slide a corner crimper across the bead while applying blows with the mallet. Properly applied with the right amount of force, crimping will fasten the metal snug to the drywall and reduce the amount of lifting.
Rigid Paper Backed Metal - Outside/Inside Corners
1) Cut all beads measured to fit with metal snips. Then set each cut upright throughout. The beginner will probably want to set one bead before making all cuts, however, to ensure right sizing of the cuts.
2) Apply mudd with your taping knife covering behind the area to be beaded.
3) Firmly push the bead into place, remembering that a mudd mix too thin will cause movement after placement, yet one too tick prevents proper leveling and adhesion. The bead should not require holding to achieve a set, regardless of the axis. Inside corner taping provides added information.
Rigid Vinyl - Outside Corners:
1) Cut with shears or a knife to fit, and set off to the side for putting up.
2) Tack on in place. Take caution with driving screws since they can deform the rigid surface.
3) When applying mudd, do in a fashion similar to the metal bead. Though with less effort as the compound moves more freely between the punched holes in the bead and the drywall surface.
Note: Apply flexible vinyl in a similar manner for bullnose cornerbead arches & curved corners.Flexible Metal Reinforced Paper
After knifing on mud for the bedding, cut the metal lined paper with snips to begin, holding the starting end stabile with your taping knife. And unreel the metal backed paper with one hand from the tape reel, while pressing the tape feed and directing its placement with the tape knife. Continuously sliding the blade over the bead with pressure to release air and level the bead. You will want to predict the end cut, about a foot or so before reaching its termination and snip apart the tape to leave a liberal amount, making sure there is enough for joint coverage (the corner should be an uninterrupted seam). Then press in place.
Any excess mudd tracks on the walls are cleaned with few passes of the taping knife.
After Embedding these Right Angle Corners:
Although the main differences for install of the above, are in attaching the beads, what follows is fairly consistent:
Knife on thinned all-purpose compound and let dry.
In preparation for the next layer of compound, run a drywall knife across the dried layer of compound to scrape off any roughness and impediments. Take care not dig into the surface and create markings.
Apply top coat(s) of compound, let dry and sand to finish
Applicable to all corners, whichever corner bead is applied:
Fastening - whenever driving screws and nails, run an old taping knife across the surface between the outer bead edge and the drywall to ensure all nail and screw heads are sufficiently countersunk.
Mudd - mix an all-purpose compound to proper consistency for setting beads, adding more water for beads without screw or nail attachements - that is, installing paper-backed metal. The viscous mix will enable manual leveling by the installer.
Topping Compound - tool on the compound in a creamy layer. After the topping is fully dry, sand off level.
Even though all purpose compounds are frequently put on, to serve as topping -- the sanding of topping compound is easiest. This is less invasive to the drywall membrane and promotes a more level surface.
Drywall Knives - as a rule, start with narrow knives and work wider with each new mudd layer. Based on the rise of the bead, and the angle of the joint, bed the first coat of compound with a 4" or 6" blade and go from there. The more conspicuous the corner, the wider the knife, reaching to 14" for highly visible areas or those having slightly uneven wallboard surfaces. Keep in mind that you will be working out of either a 12" or 14" pan.
Typically, knife on (3) total coats - one for bedding, and two top layers. Certain professionals manage to bed and top coat in (2) stages total but three is recommended.