Wallboard is one of the most common finishes for interior walls in post-World-War-II homes. It's affordable, relatively easy to work with and uncomplicated to finish with practice and the proper tools and material.
Wallboard consists of a smooth paper finish, a not-so-smooth paper backing and a gypsum core. As is plywood and paneling, wallboard is manufactured in sheets and is available in a variety of thicknesses. Sheet sizes expressed in feet are 4 by 8, 4 by 10, and 4 by 12, with 4 by 8 the most popular for do-it-yourself use. Half-inch-thick material is the most widely used, although it is also available in quarter-inch, three-eighths-inch, five-eighths-inch and three-quarter-inch thicknesses.
The thinner material is used primarily in the construction of radius or curved walls where flexibility is essential. It is also used to overlay existing wallboard or plaster to create a fresh, blemish-free finish. The thicker material can be used for a variety of purposes. Among the most common applications of five-eighths-inch material is use as a barrier to resist fire. For example, in an attached garage, the common wall with living space must be completely covered with five-eighths-inch Type X (fire rated) wallboard. Thicker material and multiple layers can also be an effective method of reducing the transfer of sound between spaces.
A wallboard panel doesn't always line up with the wall framing to which it is to be attached, and requires a cut in such circumstances. Unlike plywood or paneling which must be cut with a saw, wallboard easily can be cut using a utility knife and a metal straightedge as a guide.
Start by using a measuring tape to determine the length of the piece needed and transfer the mark to the wallboard. Next, lay the straightedge along the line of cut, then use the knife to cut through the paper facing on one side and to score part way through the gypsum core. More than one pass with the blade will make for a neater cut. Snap the wallboard core over the edge of a solid continuous support such as a saw horse. Use the utility knife to cut through the layer of paper on the opposite side. Snap the piece back in the opposite direction to neatly break the sheet off along the score mark. If no horizontal work surface is available, the board can be scored in a vertical position and snapped by placing your knee against the back of the scored line. Bend the panel toward you until the core breaks. Rough edges can be refined by using a drywall rasp.
When making a curved cut, the scoring method won't work. The simplest way to cut a curve is with a keyhole saw. To provide an opening for starting the tip of the saw blade, drill a hole with a large-diameter bit. Round holes for a ceiling light box, for example also can be cut using a wallboard circle cutting tool.
Once the wallboard has been cut it is ready to be hung with nails or screws. We suggest the latter. If the framing material is the least bit green (wet) during wallboard installation, the nail heads might eventually pop through when the wood dries. If you do decide to use nails, be sure that they are the drywall type with the cupped head, and that they are driven with a drywall hammer. The nail should be struck firm enough to leave a dimple in the wallboard. The combination of the cupped head and the dimple in the board are designed to create space for the drywall joint compound to conceal the nail head.
Drywall joint compound, joint tape (paper or fiberglass) and a taping knife (about 10 inches wide) are needed to finish the wallboard. Fiberglass joint tape is self-sticking. It is applied over the joint and covered with joint compound. Conversely, paper tape is placed in a coat of wet joint compound. When the joint compound has dried usually overnight a second coat can be applied. Increase the width of the joint compound for a smoother, less noticeable transition. The screw or nail heads should be coated a second time to account for shrinkage. After the second coat has dried, the material should be smoothed with 100-grit sandpaper on a sanding pole.
The final step prior to painting is adding texture. Whereas walls can be left smooth, wall texture helps to conceal blemishes. It generally is applied in one of three ways: with a texture knife, a spray device or a paint roller. Each of the methods produces a different effect, and each to a varying degree. The same texture method applied by two different technicians can have two very different looks. For best results, test various textures on sample pieces of wallboard before proceeding on the real thing.
