About Smooth Coats Over Drywall

Unless you plan to install a textured medium on the surface of your wall, you will likely apply paint or wallpaper. In either case, any bumps, uneven patches or dents in the drywall beneath will be visible in the final wall finish, marring the smooth look. In order to achieve a smooth wall surface, some preparation is advisable, even before you hang the sheetrock.

Function

Drywall replaces the earlier lathe-and-plaster method of constructing walls by having you nail on thin wood lathes and cover them with multiple coats of wet plaster. Drywall is sold in 4-by-8-foot (or larger) sheets; once it is installed, you need only apply smooth coats of drywall mud to the seams and nail indentations. When more seams occur in a wall, more taping is required to smooth it, so draw a drywall plan before you begin and make as few cuts as possible in the sheetrock.

Size

The larger the sheet of drywall you use, the easier it is to apply the smooth coats of drywall mud. A standard ceiling is 8 feet high, but if you have a higher ceiling, use 4-by-10-foot (or larger) drywall sheets. They are harder to hang, and you may need additional assistants, but the final wall will be much smoother.

Prevention/Solution

Premixed drywall mud comes in 5-gallon buckets and saves a lot of mixing time, but if you don't need that much, purchase a bag of powdered drywall compound and mix it as the package directs. A large mixing bit attached to a heavy-duty power drill helps smooth out lumps and blends the compound easily.

Considerations

When applying drywall compound to joints and nail indentations, use three or four thin applications, as opposed to one or two thick coats, and remove excess mud while it is still wet. For a smooth finish, keep in mind that drywall compound shrinks when it dries. Use a drywall taping knife that is at least 10 inches long to press and smooth the wet compound evenly on the joints.

Expert Insight

Use drywall tape in conjunction with the drywall compound. Drywall wall tape comes in large rolls; you will apply a flat piece to a joint immediately after you smooth on the first coat of compound. Cut the paper a few inches shorter than the length of the joint and resist overlapping the ends. Use the taping knife to smooth the paper into the wet compound. Allow one coat to dry completely before adding an additional coat. Do not add additional tape.

Warning

Once you begin applying the compound, you will realize why hanging the drywall with as few seams as possible is imperative. Because cut pieces of drywall no longer have a factory edge, the cut edge will not feature a small seam slope. To tape these joints, press the compound further out on the wall, using a larger surface to disguise an uneven area.

Resources

• Purchase drywall supplies online