Working With Wallboard
Wallboard is one of the most prevalent finishes for interior walls in post World War II homes. It’s affordable, relatively easy to work with and uncomplicated to finish. Albeit, finishing the wallboard is certainly the most complicated aspect of the entire process. It is, however, doable with practice and the proper tools and material. More on this later.
Wallboard consists of a smooth paper finish, a not-so-smooth paper backing and a gypsum core. As with plywood and paneling, wallboard is manufactured in sheets and is available in a variety of thicknesses. Sheet sizes (expressed in feet) consist of 4 by 8, 4 by 10, and 4 by 12, with 4 by 8 by far the most popular for do-it-yourself use. Half inch thickness is the most widely used material 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 a must. 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 reasons. Among the most predominant uses for five-eighths inch material is to create a barrier that will resist fire longer than will thinner material. For example, in an attached garage, the wall common 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 reduce 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, therefore necessitating a cut. Unlike plywood or paneling which must be cut with a saw, wallboard can easily 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 break the sheet off neatly 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 towards you until the core breaks. Rough edges can be refined by using a drywall rasp which is affectionately referred to as a “cheese grater.”
When making a curved cut the scoring method won’t work. The simplest way to cut a curve is by using 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 as with a ceiling light box, for example, can also be cut using a wallboard circle cutting tool.
Once the wallboard has been cut it is ready to be hung. Wallboard can be hung using nails or screws. We suggest using screws. If the framing material is the least bit green (wet) during wallboard installation, the nail heads may eventually pop through when the wood dries. Also, screws minimize potential damage from the banging which occurs when driving nails into dry, brittle framing when remodeling. If you do decide to use nails, ensure that they are drywall nails 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 ten inches wide) are the tools and materials 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 increasing the width of the joint compound for a more smooth, less noticeable transition. The screw or nail heads should be coated a second time to account for any shrinkage. After the second coat has dried, the material should be sanded with 100 grit sandpaper on a sanding pole.
The final step prior to painting is texture. Whereas walls can be left smooth, wall texture helps to conceal blemishes which are often inherent with even the most professional of hanging and finishing. Texture is generally 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. Interestingly enough the same texture method applied by two different technicians can have two entirely different looks. It may be wise to test various textures on sample pieces of wallboard before proceeding with the real thing.