How to Hide Screwheads on Stair Treads and Other Wood Surfaces

Q: I’d like to screw down the oak treads on a staircase I’m building, but I don’t want to see the screwheads. What’s the best way to hide them?

—William Mazzara, Milford, Mich.

A: I’d cover each one with a wood plug. You want plugs made of oak, to match the tread, with tapered sides and the grain running across the face. Each plug fits in a recess, known as a counterbore, drilled with a brad-point bit slightly larger than the diameter of the screwhead and slightly smaller than the plug’s widest end. The plugs’ packaging indicates which size bit to use. This is a job for flat-head deck screws; ordinary drywall screws aren’t strong enough.

Just follow these steps and no one but you will know there are screws in your staircase.

Step 1

Drill a Hole

A counterbore should be no deeper than half the tread’s thickness. So before you start, wrap some masking tape around the brad-point bit to act as a depth indicator.

Pro Tip: Norm Abram recommends using a brad-point bit slightly larger than the diameter of the screwhead and slightly smaller than the plug’s widest end: “The plugs’ packaging indicates which size bit to use. This is a job for flat-head deck screws; ordinary drywall screws aren’t strong enough.”

After making the counterbore, drill a pilot hole for the screw using a separate twist bit the same diameter as the screw’s shank. Place the twist bit in the tapered hole made by the point of the brad-point bit; that way, the pilot hole will be exactly in the center of the counterbore.

If you’re using a combination counterbore bit—a special bit that drills both a pilot hole for the screw and a recess for the screwhead in one pass—set the counterbore’s depth with a stop collar. According to This Old House Magazine, for stair treads you’ll want a pilot hole that penetrates through the tread and into the stringers or risers, with a recess about ¼ inch deep for the plug.

Step 2

Drive in The Screw

When selecting plugs, note that a dowel’s light color and exposed end grain will stand out against the grain of almost any clear-finished wood. For a much less obvious cover-up, use plugs made from a matching wood species, which allows you to align the face grain with the grain of your work. You can make your own plugs from wood scraps using a special bit called a plug cutter. Buy one that cuts tapered plugs; they’ll give you the tightest fit.

Drive each screw tight to the bottom of its counterbore. Dab the sides of the counterbore with carpenter’s glue and insert the plug, positioned so that its face grain lines up with the tread’s. Tap the plug snugly into the counterbore with a mallet.

As Tom Silva demonstrated on Ask This Old House, tapered plugs are key: “As you drive the plug in, it will tighten itself into the hole.” The plug cutter is designed to cut a plug that is actually a hair smaller than the diameter of the counterbore, so the taper creates a snug, self-tightening fit as you tap it home.

Step 3

Hide Your Work

Use a damp rag to wipe away any glue that squeezes out. When the glue dries, sand the plug flush and watch your handiwork disappear.

For an even cleaner cut, try trimming the plug with a sharp backsaw held flat against the surface before sanding. Follow up with 120-grit sandpaper to smooth out the freshly sawn spot. This two-step approach — saw first, then sand — gives you a flatter result than sanding alone and reduces the risk of accidentally dishing out the surrounding wood.