Tape dispensers hold paper or mesh tape and clip to your belt, so your tape is always ready to roll. Bigger dispensers hold a 500-ft. roll.

1111

Finally, tape up sheet plastic to isolate the rooms you’re sanding, especially if you’re living in the house. Painter’s tape will do the least dam­age to trim finishes and paint.

MATERIALS

This chapter began with sizes and types of dry – wall. Now let’s look at screws, joint tape, corner beads, and joint compound before planning and estimating supplies.

Drywall screws have all but replaced nails.

Here are the three principal types:

► Type-W screws have a coarse thread that grips wood well. They should be long enough to penetrate framing at least 58 in. In double­layer installations (two h-in. panels), use type-W screws at least 1 /4 in. long.

► Type-S screws have fine threads and are designed to attach drywall panels to light-steel framing and steel-resilient channels. At least

% in. of the screw should pass through metal studs, so 1-in. type-S screws are commonly used for single-ply li-in. or 58-in. drywall installations. If you’re attaching drywall to heavy-gauge (structural) steel, use self-tapping screws.

► Type-G screws are sometimes specified to attach the second panel of a fire-rated,
double-layer installation. That is, the first panel is the substrate to which the second panel is screwed and glued with construction adhesive. Ideally, screws should also penetrate framing, so ask building inspectors about installation requirements if your local code specifies type-G screws.

Nails are still used to attach corner bead and to tack panels in place. Ring-shank drywall nails hold the best in wood; don’t bother with other nail types. Nails should sink M in. into the wood.

Wet -SANDING

Using a large sponge to wet-sand drywall joints will definitely reduce dust, but wet-sanding isn’t feasible for a project of any size because you must rinse the sponge and change the water continually. Also wet-sanding soaks the paper facing, sometimes dislodges the tape, and tends to round joint compound edges rather than taper them. That said, if you’re drywalling a small room and don’t like moving the furniture out of the room, wet-sanding is a cleaner way to go.

Joint tape is used to reinforce drywall seams and is available as 2-in.-wide paper tape and 1/2-in.- or 2-in.-wide fiberglass mesh tape. Self­adhesive mesh tape is popular because it’s quicker. You can apply it directly to drywall seams and then cover it with joint compound in one pass. Whereas, with paper tape, you must first apply a layer of joint compound, press the paper tape into it, and then apply a coat of compound over that. If there’s not enough compound under paper tape, it may bubble or pull loose.

Still, many professionals swear by paper tape because it’s cheaper than fiberglass mesh, it’s stronger than mesh and less likely to be sliced by a taping knife, it won’t stretch, and it is lightly creased up the middle, making it easier to install and align in an inside corner. Consequently, pros use mesh tape only with setting-type compounds, which cure harder and stronger than drying-type compounds, described on p. 358.

However, self-adhesive mesh is perfect for drywall repair. If you press the mesh over a crack or small hole, you may be able to hide the prob­lem with a single layer of joint compound.

Comerbeads and trim beads finish off and pro­tect drywall edges. They’re available in metal, vinyl, PVC plastic, and paper-covered variations. Most attach with nails or screws.

Cornerbeads are used on all outside corners to provide a clean finish and protect otherwise vul­nerable drywall corners from knocks and bumps. (As noted earlier, inside corners are formed with just tape and compound.) Cornerbeads come in a number of different radii; larger bullnose vari­eties give you a dramatic curve. Whatever type you choose, though, install it in one piece.

J-beads keep exposed ends of drywall from abrading. These beads are typically used where panels abut tile or brick walls, shower stalls, or openings that won’t be finished off with trim—in other words, where the edge of the drywall is the

I Corner and Edge Treatments

finished edge. L-beads are similar; they’re used where panels abut windows, suspended ceilings, paneling and so on. In general, L-beads are easier to install on panels already in place. J – and L-beads are sized to drywall panel thickness; some types require joint compound, some don’t.

Flexible arch beads often come in rolls that are presnipped, so as you unroll them, they assume the shape of the arch you’re nailing or stapling them to. Apply joint compound and finish them as you would any drywall seam.

Joint compounds can be broadly divided into drying types and setting types. They differ in ease of use, setting (hardening) time, and strength.

Drying-type joint compounds are vinyl based and dry as water evaporates from them. They usually come premixed and are easy to apply and sand. Typically, you can apply a second coat 24 hours after the first, if you maintain a room temperature of 65°F. There’s little waste with
drying-type compound. And, once opened, it will keep for a month if you seal the bucket tightly.

Setting-type joint compounds, which contain plaster of paris, are mixed from powders. They set quickly and so allow you to apply subsequent coats before the compound is completely dry. In general, they bond better, shrink less, and dry harder than drying types. They harden via a chemical reaction, hence their nickname, "hot mud.” Depending on additives, they’ll set in 30 minutes to 6 hours. However, setting-type compound sets up so quickly and so hard that it can be a monster to sand. Once it’s mixed, you’ve got to use it up. It won’t store.

So, unless you’re a drywalling whiz, use a pre­mixed, all-purpose, drying-type joint compound. A 5-gal. bucket will cover 400 sq. ft., roughly, a 12-ft. by 12-ft. room. with 8-ft. ceilings. The com­pound is ready to use right out of the bucket. It’s reasonably strong, and each application should dry in a day.

One further distinction: Drying-type and set­ting-type joint compounds are further formulated as either taping compounds—used for the first coat, in which you embed the tape—or topping compounds, used for the second and third coats because it feathers out (thins) better and dries faster. Again, all-purpose compound can be used for all three coats, but you might want to experi­ment with the two types once you’ve had some practice. Some pros use setting-type joint com­pound for the first and second coats and drying – type for the third (and last) coat.

PLANNING THE JOB

Before estimating materials, walk each room and imagine how best to orient and install panels. These five rules, known to drywall pros, will save you a lot of pain.

Rule 1: Use the longest panels possible. This minimizes the number of joints. A 4-ft. by 14-ft. or 4-ft. by 16-ft. panel is heavier and less wieldy than a 4-ft. by 8-ft. panel. But hanging larger panels is relatively fast, compared to the time it takes to tape, coat, and sand the joints of the smaller panels.

Rule 2: Think spatially. Running panels hori – zontally—perpendicular to studs and ceiling joists—can reduce the number of joints and pro­mote stronger attachments. For example, two 4-ft. by 12-ft. wall panels run horizontally will reach an 8-ft. ceiling and create only one hori­zontal seam to be filled. Two 54-in.-wide (4/2-ft.) panels run horizontally will reach a 9-ft. ceiling. However, if ceilings are higher than 9 ft., you may be able reduce the number of joints by installing wall panels vertically (parallel to studs).

Rule 3: Minimize butt joints. Long edges of pan­els are beveled to receive tape joints, but the short edges (butt edges) are not. Consequently, butt joints are difficult to feather out, and they are likely to crack. So try to minimize the number of butt edges. Where you can’t avoid them, position them away from the center of a wall or ceiling. Last, always stagger (offset) butt joints; never align them. Otherwise, you may need to feather joint compound out 3 ft. wide to get a barely acceptable joint.

Rule 4: Install drywall that’s thick enough.

Otherwise spans may sag between ceiling joists and bow between studs. For example, if you’re running panels parallel to ceiling joists spaced 24 in. on center, 58-in. drywall is much stronger and less likely to sag than ’/2-in. panels. For this, be sure to comply with local codes.

Rule 5: Don’t scrimp on panels. Expect a cer­tain amount of waste, especially if you’re installing around stairs or sloping ceilings. It’s a mistake to try to piece together remnants, because that creates a lot of butt joints and looks awful. Likewise, scrimping on screws or joint compound results in weak joints and screw pops.

People have Idings since

prehistoric times. Archaeologists have unearthed plaster walls and floors dating to 6000 B. C. in Mesopotamia. And the hieroglyphics of early Egypt were painted on plaster walls. In North America, plaster had been the preferred wall and ceiling surface until after World War II, when drywall entered the building boom. Although drywall represents a historic shift in building technology, the shift was more one of evolution than revolution because drywall’s core material is gypsum rock—the same material used since ancient times to make plaster.

Drywall

Sometimes called Sheetrock® after a popular brand, drywall consists of 4-ft.-wide panels that are screwed or nailed to ceiling joists and wall studs. Sandwiched between layers of paper, dry – wall’s gypsum core is almost as hard and durable as plaster, though it requires much less skill to install. Appropriately, the term drywall contrasts these dry panels with plaster, which is applied wet and may take weeks to dry thoroughly.

Panel joints are concealed with tape and usu­ally three coats of successively wider layers of joint compound that render room surfaces smooth. Each panel’s two long front edges are slightly bev­eled, providing a depression to be filled by joint tape and compound. Note: Each layer of joint com­pound should be allowed to dry thoroughly before sanding smooth and applying the next coat.

DRYWALL TYPES

Drywall’s paper facing and core material can be manufactured for special purposes to make it more flexible, water resistant, fire resistant, sound isolating, scuff resistant, and so on. The upcoming pages will help you determine the size and type of drywall you choose.

► Where it will be used. Local building codes may require water-resistant (WR) dry – wall in high-humidity rooms or fire-resistant (type-X) panels elsewhere to retard fires.

► Distances it must span. Because gypsum is relatively brittle, the drywall must be thick enough to span the distance between ceiling joists without sagging and between wall studs without bowing (see "Drywall Types, Uses, and Specifications," on p. 352).

► Skill and strength of installers. The longer the sheets, the heavier and more unwieldy they are to lug and lift, especially

a concern if you’re working alone or if ceilings are high.

► Access to work areas. Using sheets longer than the basic 8 ft. reduces the number of end joints that need taping. But these jumbo 14-ft. and 16-ft. panels are practical only if your doors and stairwells are large enough to admit them.

Regular drywall comes in four thickness:

‘A in., 58 in., ‘A in. and 58 in; and in sheets 8 ft. to 16 ft. long, in 2-ft. increments. There are also 4-ft. by 9-ft. sheets. To minimize wall joints when installing drywall horizontally, regular drywall also comes in 54-in. widths.

The most commonly used thickness is ‘A in., typically installed over wood or metal framing.

A sheet that size weighs about 70 lb., still man­ageable for strong people working solo.

To increase fire resistance and deaden sound, you can double up 52 in. panels, but that may be overkill. More often, a single layer of 58-in. dry – wall is used for those purposes. Being stiffer, 58-in. panels are harder to damage, so they’re a smart idea in hallways if you’ve got kids. And they’re less likely to sag between ceiling joists and bow between studs.

Renovators commonly use ‘/4-in. and 58-in. sheets to cover damaged surfaces and thereby avoid the huge mess of demolishing and remov­ing old plaster. For best results with this thin dry – wall, use both construction adhesive and screws to attach it. However, neither thickness is sturdy enough to attach directly to studs in a single layer.

Because they’re thin and flexible, two layers of ‘4-in. drywall are routinely bent to cover curving walls, arches, and the like. Attach the second layer with construction adhesive and screws. If the curved area has a short radius (5 ft. to 5 ft.), wet the drywall first (discussed in detail later in this chapter). There’s also a ‘4-in. flexible drywall with

heavier paper facings designed for curved sur­faces, but this usually needs to be special-ordered.

Water-resistant drywall (WR board) is also called greenboard, after the color of its facing. Its water-resistant core and water-repellent face are designed to resist moisture in bathrooms, behind kitchen sinks, and in laundry rooms. In general, it is a good base for paint, plastic, or ceramic tiles affixed with adhesives, and for installation behind fiberglass tub surrounds.

Although WR board can cover most bathroom walls, it should not be used above tubs or in shower stalls. In particular, it’s not recommended as a substrate for tile in those areas because sus­tained wetting and occasional bumps will cause the drywall to deteriorate, resulting in loose tiles, mold, and water migration to the framing behind. As a substrate for tile around tubs and showers, cementitious backboard is a far more durable and cost effective. Mortar is also durable there, but more expensive.

For the reasons just cited, don’t install WR board over a vapor barrier, especially if this drywall will later be painted with oil-based paint, papered with vinyl wallpaper, or otherwise covered with a vapor-retarding membrane. Sandwiched between two impervious layers, the drywall will deteriorate.

Fire-resistant drywall (also called type X) is specified for furnace rooms, garages, common walls between garages and living spaces, shared walls in multifamily buildings, and so on. The thicker the type-X drywall, the higher the fire rat­ing: 45 minutes for 14 in., 1 hour for 58 in., 2 hours for 54 in. Fire-resistant drywall has a core rein­forced with glass fibers, making it more durable and somewhat harder to cut.

Most codes specify 558-in. drywall for single­family residences—a thickness also adequate to span garage ceiling joists spaced 24 in. on center.

Other specialty drywalls are available. Foil – backed drywall is sometimes specified in the Cold Belt to radiate heat back into living spaces and prevent moisture from migrating to unheated areas. Abuse-resistant drywall, sound-mitigating drywall, and vinyl – and fabric-covered panels with prefinished edges are also manufactured.

Blueboard is a base for single – or two-coat veneer plastering and is now widely used instead of metal, wood, or gypsum lath. It is available in standard 4-ft.-wide panels.

Gypsum lath is specified as a substrate for traditional full-thickness, three-coat plastering.

Its panels are typically 16 in. by 48 in.

Cementitious backerboardhas a core of cement rather than gypsum. Used as a tile sub­strate, it is installed much like drywall (see Chapter 16 for details).

TOOLS

You can install drywall with common carpentry tools—framing square, hammer, tape measure, utility knife, and chalkline. Still, a few special­ized, moderately priced tools will make the job go faster and look better. If you’ve got high ceil­ings, rent scaffolding.

Layout tools include a 25-ft. tape measure, which will extend 8 ft. to 10 ft. without buckling; a 4-ft. aluminum T-square for marking and cutting panels; a chalkline box for marking cut­lines longer than 4 ft.; a compass or a scriber to transfer out-of-plumb wall readings to inter­secting panels; and a 2-ft. framing square to transfer the locations of outlet boxes, ducts, and such onto the panels.

Cutting and shaping tools may be simple, but must be sharp. Drywall can be cut with one pass of a sharp utility knife, a quick snap of the panel, and a second cut to sever the paper backing, as shown in the center photo on p. 562. Buy a lot of utility-knife blades and change them often; dull blades create ragged edges. Use a Surform® rasp to clean up cut drywall edges. The sharp point of a drywall saw enables you to plunge cut in the middle of a panel without first drilling, though the edges of the cut will be rough.

A drywall router or a laminate router with a drywall bit is the pro’s tool of choice for quick, clean cuts around electrical outlet boxes, ducts, and the like. With a light touch and a little prac­tice, you can use this tool to cut out boxes

already covered by drywall panels, as shown in the photo on p. 363.

Similarly, you can use a utility saw to cut out the waste portion of a drywall panel that you’ve "run long” into a doorway or window opening.

Lifting tools will help get you or the drywall up into place. Two lifting tools can be handmade: A panel lifter is just a first-class lever inserted under the bottom of a panel to raise it an inch or so, leaving your hands free to attach the drywall. Metal lifters are not expensive, but 1×2 scraps work almost as well.

The second homemade tool, a T-support, temporarily holds a panel against ceiling joists while you attach it. Cut a 2×4 T-support about h in. longer than the ceiling height so you can wedge it firmly against the panel. Or you can rent a hydraulic stiff arm, an adjustable metal version of a T-support.

For taping and sanding, some pros swear by stilts, but they’re awkward and ill-advised for amateurs. Already off-balance from working over your head, you could easily fall backward and injure yourself. For that reason, stilts are banned by many state regulatory agencies and excluded from most workers’ insurance coverage.

Adjustable drywall benches should enable you to reach 8-ft. or 9-ft ceilings easily. Alternatively, you can lay planks across sturdy wooden saw­horses.

Ultimately, renting a drywall lift and/or scaf- foldingis the safest way to go, especially if ceil­ings are higher than 10 ft. If there’s no danger of falling off your work platform, you can focus on attaching drywall. Scaffolding is also indispen­sable during the taping and sanding stages.

Attachment tools are typically a corded screw gun or a drill with screw bits to attach drywall.

A cordless drill with screw bits is fine for a drywalling a room, but pros who have thousands of screws to drive use corded screw guns, which have clutches and depth settings that set the screws heads perfectly—just below the surface. The pros also use a drywall hammer for incidental nailing. A standard carpenter’s hammer will do almost as well, but the convex-head of a drywall hammer is less likely to damage the paper facing of a panel, should you need to drive down a nail.

Adding a self-feeding screw attachment to the screw gun would probably speed up the job, but few pros use them. Finally, if you’ll be installing double layers of drywall, use a caulking gun to apply construction adhesive to the outer face of the first layer.

Taping and finishing tools are used to apply joint compound through to sanding the joints. The workhorse of taping is the 6-in. taping knife, perfect for filling screw holes, spreading a first layer of joint compound, and bedding tape.

To apply the successively wider and thinner second and third coats of joint compound, you’ll need wider taping knives or curved trowels.

Taping knives typically have straight handles and blades 10 in. to 24 in. wide; a 12-in.-wide knife will suffice for most jobs. Trowels have a handle roughly parallel to the blade and a slightly curved blade that "crowns” the compound slightly. Trowel blades run 8 in. to 14 in. long.

Applying "mud” (joint compound) takes finesse, so most pros use a mud pan or a hawk to

the vanishing Nail

Drywall screws install faster than drywall nails. They also hold better and are less likely to damage a panel’s paper facing. Ring-shank nails are used to tack up panels, but screws take over from there. Besides, screws are quiet and nonconcussive, so installers are less likely to disturb finish surfaces, tottering vases, or feisty next-door neighbors.

hold enough mud to tape several joints. As they work, drywallers are constantly in motion: scoop­ing mud, centering it on the knife blade, scraping off the excess, and returning it to the pan or onto the hawk.

Comer knives enable you to apply mud to both sides of an inside comer simultaneously. To finish outside corners (those that project into a room) consider making your own tool.

Boil a plastic flat knife, and once it’s soft, bend into the shape you need, as shown in the photo at right.

For high-volume jobs, you can rent taping tools that dis­pense tape and compound simultaneously. See “Mechanical Taping Tools,” on p. 369, for more information.

Sponges and a pail of water will keep tools clean as you go.

Even tiny chunks of dried com­pound will drag and ruin freshly applied layers, so rinse tools often, and change water often.

A perfectly clean 5-gal. joint compound container is a great rinse bucket. Use a second one to store and transport delicate trowels and knives.

Sanding equipment starts with special black carbide-grit sandpaper, which resists clogging by gypsum dust; it comes precut to fit the rubber­faced pads attached to poles and hand sanders. Sandpaper grit ranges from 80 (the coarsest) to 220 (fine); 120-grit paper is good to start sanding with. Finish-sand with 220-grit or a rigid dry – sanding sponge (a special sponge that is never wetted).

A sanding pole with a pivoting head enables you to sand higher—8 ft. ceilings are a snap— and with less fatigue because you use your whole upper body.

Sanding joint compound generates a prodi­gious amount of dust, so buy a package of good – quality paper dust masks that fit your face tightly; they’re cheap enough to throw out after each sanding session. If you’re sanding over your head, lightweight goggles and a cheap painter’s hat will minimize dust in your eyes and hair.

A shop vacuum with a fine dust filter is a must; vacuum at each break so you don’t track dust all over the house. Dust-free sanding attachments are available for shop vacuums (as shown in the top photo on p. 356). Although they virtually eliminate dust, they’ll sand through soft topping coats and expose the joint tape in a flash if you’re not careful. For best results, run them at low speed settings and use fine, 220-grit sandpaper.

A dust-free sander attached to a shop vacuum cuts dust dramatically, but in unskilled hands it will oversand soft topping coats.