Installing Drywall (Wallboard)

The most common way to finish walls and ceilings is by installing drywall to the framing and ceiling joists. It is also called gypsum wallboard, sheetrock or sometimes just “rock.” It is available in 4X8, 4X12, and 4X16 foot sheets; in 1/4-inch, 3/8-inch (becoming increasingly difficult to find because it is not commonly used), 1/2-inch, and 5/8-inch thicknesses.

Most local building codes require that perimeter walls and staircases of a building have 5/8-inch thickness for enhanced fire resistance. 4X8 sheets of drywall have a grey backing; longer sheets have white.

Drywall is also available in a water-resistant form for use in bathrooms. It can be identified by its light green paper covering instead of the standard white. Drywall is not a suitable substrate for installing ceramic tile; use cementboard, instead.

Once insulation has been installed, and vapor barrier (if included) in place, walls and ceilings are ready for drywall.

Basics

If any wall studs or joists look out of alignment, check them using a straight edge. Shim recessed wall studs and ceiling joists using paper drywall shims, so the wall is relatively even.

Wall framing studs have a “crown” side; one that slightly bows outward. Most framers put the crowns all on the same side. This causes the wall to be slightly concave (curved in) or slightly convex (rounded), depending on crown placement.

Starting at one end of the wall and pushing sheets tightly against a curved wall will throw the joints off. So, if what you desire is a concave wall, first snap a chalk line across the framing studs 4-feet out from the ends of the wall; lay the first row of drywall to that line. For a convex wall, you would snap the chalk line 4-feet from its innermost point.

The long edges of drywall are slightly tapered. When two sheets butt against the other it forms a shallow “hollow, with the seam in the middle. This allows for easier taping. When long sheets are installed horizontally, ends butt together without forming a hollow. The resulting seam can be somewhat more difficult to tape.

The horizontal method will produce fewer seams. It will also result in waist-height seams that are less noticeable than 4-foot interval vertical seams. The difference in appearance is especially noticeable near the ceiling area.

The Ins and Outs of Drywall and What you will Need

When purchasing drywall keep in mind that it must be carried into the job site. Longer sheets will be more difficult to maneuver, and may not fit through some passage ways.

Also keep in mind that drywall is relatively heavy and awkward to carry. For that reason it may well be worth the extra money to have the building supply store where it was purchased deliver it to the job site.

It may also be worthwhile to purchase more sheets than what you feel is needed; in case of breakage, or measurement or cutting miscalculations. This will reduce the risk of having to make a return trip to the store for more at a later time.

Drywall is fastened using either screws or nails driven through the sheet into the wall stud or ceiling joist beneath. Although most do-it-yourselfers find nails easiest to use, screws will be stronger. Sometimes a bead of glue is also used for additional support. It will take about 5-pounds of 1 1/2-inch drywall screws or 1 3/8-inch drywall nails (ring-shank nails will not hold as well as drywall nails) per 1,000 square feet of drywall.

Even when using screws, be sure to get some nails for corner bead. When using glue, use an adhesive such as PL-200, which comes in a tube-like caulk. Allow a large 32-ounce tube for every three 8-foot sheets of drywall.

Corner bead is available in plastic or metal strips; it is used to finish corners and certain edges. Metal corner bead makes a durable 90-degree corner; if you want a rounded edge, use bull-nosed bead.

Segmented bead is suitable for rounded openings; flexible corner bead is available for edges other than 90-degree. Inside corners are simply finished with tape and drywall mud (joint compound); J-bead is used for inside corners where a new wall butts up to a finished or concrete wall.

Other Considerations

Drywall compound or “mud” is a mixture of gypsum and water used to cover seams, screws, and nails. When dry, it is easily sanded to make a smooth surface which does not show seams and fasteners. Approximately 140-pounds of compound will be needed for 1,000 square feet of drywall. A 5 gallon bucket weighs 62-pounds; it is also available in 40-pound boxes.

Compound comes in 2 grades; “all-purpose,” and “topping” or “finishing.” All-purpose can be used for all phases of taping, patching, and texturing. Topping grade is slightly thinner and smoother; making it easier for use as a final coat on seams, or for texturing. Buy extra; it will be less expensive to have more than what is needed than to have to drive back to the store for extra later.

As drywall compound dries, it shrinks. So, if you are patching large areas or holes it is best to use a product such as Durabond. It comes in powder form and is mixed with water; dries quickly, and does not shrink. Be careful, however, to purchase the right type. Durabond comes in 2 types; one is sand-able, the other sets up very hard.

Paper drywall tape is about 2-inches wide and sold in rolls. It is used with drywall compound to reinforce and hide drywall seams. A thin coat of compound is spread on the seam; once dry, the tape is placed over it. And then another thin coat of compound is smoothed over the tape.

Some people prefer using plastic mesh tape, which is slightly adhesive on one side. Mesh tape is a little more expensive, but may well be worth the additional expense for the novice DIY installer. To use, simply press it over seams, and cover with mud.

The Installation Process - Start with the Ceiling

When you begin installation, always start with the ceiling. Anyone who has ever mounted drywall on a ceiling knows it is a nearly impossible task without one or more helpers to hold it in place.

The use of a drywall jack can simplify things immensely. A sheet of drywall can be placed on the jack, hoisted into place, and then fastened to ceiling joists after being adjusted for a precise fit.

Be sure and measure accurately. Install drywall so that sheets run lengthwise across the ceiling or at a right angle to joists; with end seams falling as close to the middle of the joist as possible. Use a pencil to mark lines for easy placement of fasteners.

When fastening, start with ends. Rule of thumb is to space fasteners about 8-inches apart. Around the edges, place one fastener at each joist. Add 6 fasteners along each joist line, in pairs spaced 2-inches apart. Space pairs evenly along joist line. When taping, fasteners can be covered with drywall compound with a stroke of the drywall knife.

Note: building codes have very strict regulations about how many fasteners are required to attach drywall. Be sure and check your local building code requirements.

Most professional drywall installers use a screw gun with a special adapter that disengages screws at a proper depth. Attachments are available for a regular or cordless screwdriver that works in the same way. Avoid using the clutch on a cordless screwdriver. It could result in inconsistencies in screw depth.

Screws that are too deep break the paper, causing a raised area in the drywall. Screws not driven in far enough protrude above the finished surface, and make taping and patching difficult.

Measure accurately when pre-cutting openings for light fixtures and HOT WIRE vents. If you prefer, you can tack the drywall up in place and then cut openings using a drywall router or a drill with a zip bit.

When installing the next row of sheets, be sure to arrange them so that end joints are staggered from the first run of sheets. Occasionally, a piece may finish just short or just past a joist. Either cut the piece, or add a 2X4 to the side of the joist, then attach the drywall.

Walls

Once the ceiling has been installed, begin the walls. Butt the first run on each up to the ceiling. In some rooms longer sheets will span the entire wall. However, if drywall needs to be pieced, make sure joints will fall in the middle of a framing stud.

When installing drywall around a door or window, carefully measure and pre-cut openings. Use just a few fasteners to tack up a sheet of drywall right over the opening, and then cut with a drywall router. A drill and zip bit also works well. Once the opening is cut to fit, install the rest of the fasteners. Note: openings for wall outlets, switch panels, and HVAC vents should be cut in this same manner.

When cutting full sheets for a custom fit, use a large T-square, and then score the drywall on the line you want cut using a utility knife. Carefully push the waste piece away from the cut; the gypsum core of the drywall should “pop” and break on the line. On the back side, cut the paper along the break line using a sharp utility knife. Use a Surform plane to straighten and smooth the edge for a tight-fitting joint.

If the ceiling is less than 8-feet, the bottom run of drywall will have to be cut lengthwise. When installing the bottom run, allow a gap of 3/8 to 1/2-inch at the bottom. Use a pry bar to gently lift the sheet off the floor, and then fit snugly into place. Leaving a gap will help prevent moisture from wicking up into the drywall if the floor gets wet. Note: if there is enough water present in a water damage/flood situation, drywall with an insufficient gap at the bottom can wick the moisture 4-feet or more up into the wall, causing un-repairable damage.

Before starting on the bottom run, mark the position of the framing studs so that once drywall installation is complete, there will be a reference for installing baseboard moldings.

Corner Beading

Once drywall has been fastened in place, outside corners will need corner bead to protect the corner and allow proper finishing. Corner bead is simple to install. Simply place over the corner and nail it in place using the smaller holes; spaced at about 6-inch intervals.

There is a trick to proper corner bead installation:

• Take a short piece of corner bead and hold it against a corner.
• Place a 6-inch drywall knife with one corner touching the corner bead edge, the other touching the surface of the drywall beyond the corner bead.
• There should be about a 1/16-inch gap between the knife and the nailing edge of the corner bead.

When properly nailed in place, the 1/16-inch gap allows the drywall compound to be spread in a layer just thick enough to hide the corner bead, yet blend in well with the surface of the drywall.

Pushing too hard will make contact between the drywall knife blade and the nailing flange. If the spine of the corner bead is pulled out too far, the corner will exceed 90-degrees, making it difficult to install the base molding.

Finishing Up

After beading is properly installed and drywall joints (seams) neatly taped, the final step is to apply drywall compound. This can be a difficult task to perform properly, and may take practice. A poor job will be highly visible. But with practice and by following basic techniques, even a do-it-yourselfer can achieve a wall finish with finesse.

There are 3 “stages” of drywall finishing; each involves the application of drywall compound. First, cover screw and nail heads, then fill joint cracks. Finally, apply 2-inch joint tape to reinforce joints. Use either paper or plastic/fiberglass mesh, whichever you prefer. Most beginners find fiberglass mesh easiest to work with.

How to Apply Drywall Compound and Tape

Before starting, make sure no nails or screw heads protrude above the wall surface. Accomplish this by running the edge of a 4-inch drywall knife over the wall; listen for the ping of metal on metal. Drive any protruding heads further in, so they are below the surface of the drywall.

Buttjoints are usually done first, then flat joints, (factory-recessed edges), and then ceiling-to-wall joints. By starting with the buttjoints, ceiling corner tape and flat joint tape will cover butt joint tape.

Use a 6-inch drywall knife; take small dabs of compound from the pan, and trowel them across the joint along its entire length. Lightly smooth with the trowel. Next, place a piece of tape over the joint; press it lightly into place. Cut it off at the end of the joint.

For vertical joints, start in the middle of the joint and work out to the ends. Using modest pressure, pull a 6-inch knife along the joint; pushing the paper slightly into the compound, squeezing out the excess. Be careful not to press too hard and squeeze too much of the compound out, or the tape will not stick to the wall and will bubble.

Gently clean off ridges of excess mud at the edges of the tape; smooth one final time from the middle of the joint, and then leave it. The tendency most novices have it to keep smoothing it; but once you’ve followed the above process, leave it alone and move on.

The concept is to use as little compound as possible, while at the same time getting just enough on so that the tape has something to stick to with no dry spots that will bubble. It takes practice to get the feel for just the right amount of compound. When sanding, keep it to a minimum.

Once buttjoints are dry, do the flat joints in the same manner. Start in the center and work out towards the ends. By waiting until the buttjoints are dry, there is no risk of pulling the butt joint tape loose when intersecting.

Inside corner joints are handled like butt and flat joints, but are more complicated because of the right angle. Place dabs of mud along the joint, and smooth using a 6-inch drywall knife. When taping, use your fingers to crease the tape along the factory ridge in the center. Gently push the tape into the corner and smooth it along the drywall surface with your fingers.

Trim to fit at the ends, which can be ½-inch shorter than the joint. Start at the center; push the tape into the corner. Trowel one side towards the joint end using a 4 or 6-inch drywall knife. Do the same along the opposite edge.

Be careful to leave enough of the compound under the tape so it will adhere correctly. Tip: allow wall-to-ceiling inside corner joints to dry before starting on vertical wall-to-wall inside corner joints.

If outside corner bead has been properly installed, applying mud will be easy. Simply dab mud along both sides of the corner, and then smooth using one edge of the drywall knife. One edge of the blade should be slightly straddling the corner, the other riding along the wall. Smooth off any ridges of excess mud, and then leave it alone.

Applying the Second Coat of Compound

Once everything has dried, carefully apply a second coat of compound to fill in low spots and cover any defects in the first coat. This will also help feather the taped and mudded surfaces into the drywall surface. If the first coat was properly applied, sanding between first and second coat applications will not be necessary.

Remove any ridges or dried blobs of compound with a 6-inch knife. Be thorough; any bumps or ridges left behind will be difficult to deal with later. Use the same order of application used with the first coat, but use a 12-inch drywall knife instead of 6-inch.

Start with the buttjoints; trowel mud up along one side of the joint, and then the other. It might take a second pass to get an even coat. Once you have an even coat on both sides, make one more pass on each.

Put slightly more pressure on the outside of the blade; you want to feather compound from a slight ridge in the center of the joint, while blending it to the wall edge. Then leave it alone and move on.

Finish all buttjoints and let them dry before starting flat joints; do the same before moving to corner joints. You’ll also want to second coat the screw and nail heads as you work.

Applying the Skim Coat

Before you begin the final or skim coat, again scrape off any dried lumps, ridges or slops. If there are problem areas, you can sand them. But full sanding comes later.

The skim coat fills any imperfections in the joints or feathering using a thinner, lighter compound. Use a 12-inch blade on butt and flat joints; a 6 or 8-inch blade for corners, nail and screw heads. Because the coat goes on thinner, it dries much faster.

Once the final coat is thoroughly dry, full sanding can begin. Sanding drywall will produce an abundance of fine white dust. Therefore, it is a good idea to seal off the area using plastic sheeting to minimize dust intrusion to other areas of the structure. If there are windows that can be opened with fans venting air to the outside, it will help.

Be sure to wear a dust mask and safety glasses or goggles. If applications of tape and compound have been properly administered, a minimum of sanding will be necessary. The surface just needs to be smooth for primer and painting.

While sanding, go lightly. The idea is just to minimize humps over joints, not create a perfectly flat surface. Small ridges will quickly disappear; be careful not sand into joint tape or drywall paper. If you do, circle them with a pencil to repair later, and move on. When finished, use a trowel to skin the areas, including any crevices that didn’t sand out. Let dry, then sand lightly.

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