A drywall corner bead is a building material used as part of the drywall finishing process. It is made from a thin strip of vinyl or aluminum that is bent at a 90 degree angle. The corner bead has a series of small holes in its surface that help it bond with joint compound or Spackle® during installation. This material is available in standard lengths ranging from eight to twelve feet (2.4 to 3.7 m), with each of the two sides measuring from 1 inches (25.4 mm) to 1.75 inches(44.5 mm) in width.
The drywall corner bead is used to create a smooth, seamless surface along drywall corners and intersections. It also reinforces the drywall and helps prevent dents, scrapes and other signs of damage. Finishers may use a drywall corner bead on a wide variety of applications. These devices are typically used on both inside and outside wall corners, along the perimeter of the ceiling, and around doorways or arches.
To install a drywall corner bead, one must first hang and tape the drywall as usual. As joint compound is added to each seam, it is also applied in a thin coat around corners and intersections. While the compound is still wet, a corner bead is pressed tightly over the corners and left to dry. To maintain a seamless look, a single length of material should be used on each corner. Using two shorter lengths to cover the corner will usually result in a visible joint.
Drywall finishers have a number of different types of corner beads to choose from depending on the application. The traditional drywall corner bead is used on inside and outside corners that meet at a 90 degree angle. Corners that meet at odd-sized angles will require the use of adjustable drywall beads, which typically expand from 70 to 150 degrees. Walls subject to high levels of abuse may require extra large corner beads, which have extended sides to help protect a larger area.
There are also a number of specialty units available for more intricate applications. An archway drywall corner bead is used to construct arches and other curved surfaces. One side of the bead is tabbed to allow installers to flex it around a curve as necessary. Archway beads can be used on both interior and exterior corners or intersections. A skim coat bead is used for plasterboard or stucco applications, and has larger holes in its surface to hold a greater quantity of mortar or adhesive.