Best practices in finishing drywall
Looking for some best practices in finishing drywall? These best practiices here will help you with all your drywall finishing jobs.
Before starting to embed tape and finishing drywall look for damaged areas such as damaged seam edges. Cut out the loose areas, pre-fill with compound and, if necessary, cover the areas with mesh tape.
Any gaps between panels that are more than ⅛-inch wide are often prefilled with a setting compound, which can be coated over when set up. It does not have to air dry and is available in a variety of setting times from 20 to 90 minutes.
If there is time for the compound to dry before starting to embed the tape, prefill with a drying-type compound, but if taping is to be done soon prefill using a setting compound.
When using paper tape or fiberglass matt tape, the compound needs to be applied over the seam first with a 5- or 6-inch knife about ⅛-inch to ¼-inch thick. Apply compound evenly leaving no dry areas.
Next center the tape on the joint, pressing it lightly into place every foot or so, keeping the tape pulled tight as you progress. Pull the taping knife along the center of the tape starting in the middle and working toward each end.
Apply quite a bit of pressure with the taping knife pushing most of the compound out and embedding the paper tape tightly into the compound. Be sure the tape is below the plane of the drywall face.
If you’re using fiberglass matt tape, it won’t require as much pressure to embed because the compound pushes through the tape as it’s embedded. Too much pressure can tear the matt tape.
If you’re using fiberglass mesh tape, the self-adhesive tape is adhered over the seams before compound is applied. Using a hawk or a beveled trowel as a palate apply a thin even layer of setting compound about ¼-inch thick along the entire length of the seam.
Use the beveled trowel or a taping knife to smooth the compound, leaving a thin layer of compound over the tape and keeping the edge feathered out and the center below the plane of the drywall surface, one pass is usually adequate.
Once embedded all three types of tape are concealed and finished in the same manner.
Best practices in finishing drywall: The fill coat
The long edges of drywall panels have beveled edges to accommodate the tape and compound of the first coat while still leaving a recess that is filled during the fill coat. This second coat covers the tape and fills the recessed area along the seam.
An all-purpose lightweight joint compound is great for the fill coat (second coat). Many finishers prefer the lighter weight all-purpose compounds because they shrink less, dry faster and sand easier that the compounds described above to embed the tape.
A great drywall tool to use to smooth the fill coat is a 4½-inch x 14-inch curved trowel because it feathers the edges and leaves the desired crown along the center.
Apply joint compound over the seam about 8 inches wide with a taping knife. A wide taping knife can be used but using a narrower knife (6 inches) provides a little more control.
Once the compound is applied, hold the trowel at about a 20-degree angle away from the seam and pull the trowel along while applying enough pressure to feather both edges along the seam. Leave enough compound to cover the tape. It will take more than one pass with the trowel to achieve the desired finish.
The finished fill coat should be about 10 inches wide with edges feathered and a slight crown of compound left along the center. That slight crown is necessary to allow for shrinking as the compound dries and for sanding.
Best practices in finishing drywall: The finish coat
Before starting the finish coat, brush over the taped areas with a drywall sander using 220 grit paper. Brush, don’t sand. You just want to knock off ridges and trowel marks, and any little chunks of compound or poorly feathered edges.
The finish coat is a thin coat of compound that, when properly applied, will leave a very smooth surface with tightly feathered edges. The brushing helps make this easier to achieve. There should be very few imperfections except for maybe a few trowel marks around seam intersections after the finish coat is applied.
For best results, use the same compound used for the fill coat, thinning it down slightly with approximately two to four cups of water per 5-gallon bucket. Apply a thin coat of compound over the seams with a taping knife and then remove it using a 12-inch knife, leaving a thin skim coat over the seams.
With the finish coat, small imperfections are filled and blended in and the seam is widened slightly as the edges are feathered in. Apply the compound over the full length of shorter seams and for 6 to 8 feet section of longer seams. Remove the compound with the wide taping knife by holding the knife at roughly a 70 degree angle from the surface.
A 9-inch paint roller with a ¾-inch nap can also be used to apply the compound.
Best practices in finishing drywall: Sanding
Sand the joints using a pole sander with 220 grit paper or a rotating/dust control sander. Don’t over sand, deeper scratches or dents should be filled, not sanded into a depression.
When rough sanding is complete, begin touch-up sanding with a dry sanding sponge with fine grit and hand sander. While the sanding sponge allows you to get into tight areas and feather the edges, the hand sander removes bumps and ridges that the sponge would just round off.
As you sand, inspect the area with a bright light, moving the light along as you sand to examine the area at various angles.
Keep a drywall knife with some fresh compound nearby while sanding to fill in deeper scratches or dents that won’t sand out.
Selecting the tape
For taping, use pre-creased paper tape, pre-creased fiberglass matt tape or fiberglass mesh tape. Paper tape is the most commonly used. It can be embedded in taping compounds, any all-purpose drying compound and setting compounds.
Fiberglass matt tape is relatively new. It’s gaining in popularity because it’s inorganic so it’s naturally mold resistant and it’s easy to embed in joint compound, especially on seams. Fiberglass matt tape works best with all-purpose ready mixed compounds.
Fiberglass mesh tape is self-adhesive and is put in place before the compound is applied, so it’s fast and easy to use. However, it’s not as strong as paper or fiberglass matt tape, so it must be embedded in a setting compound to give it added strength.
When a level 4 finish isn’t adequate
The taping described here is a level 4 finish as defined by the Gypsum Association.
“All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compounds shall be smooth and free of tool marks and ridges. This level should be specified where flat paints, light textures or wall coverings are to be applied.”
A level 4 finish may not be adequate if paint with a sheen is used, especially in critical lighting areas. As drywall is finish taped and lightly sanded, different textures and porosities are created.
While in most applications, a prime coat and finish coat of paint will look great, occasionally very strong lighting, such as side lighting from windows or fixtures that cast light across the painted drywall can exaggerate irregularities, called “joint photographing.” Joint photographing is the shadowing of the finished joint areas through the surface decoration.
−By Myron Ferguson, Ferguson Drywall Innovations, Middle Grove, New York