How to Install Cove Molding Under Stair Nosings

Begin by measuring the length of each stair nosing where you intend to install the cove molding. Use a measuring tape for accuracy. Once you have the measurements, transfer them to the cove molding. Mark the exact cut points on the molding with a pencil. For angled cuts (often needed at the ends of nosings or where the molding turns a corner), use a speed square or miter box to ensure the correct angle is marked.

Using your marked measurements and angles, carefully cut the cove molding. A miter saw is recommended for the most accurate and clean cuts, especially for angled joints. If using a handsaw, ensure you have a miter box to guide the blade for precise angles. Cut slowly and steadily to avoid splintering the molding. Make test cuts on scrap pieces if you are unfamiliar with your saw or the material.

Before applying any adhesive or fasteners, place the cut pieces of cove molding into their intended positions along the stair nosings. Check that each piece fits snugly and that the angles at the corners or joints align correctly. Look for any gaps or areas that do not meet flush. This is the crucial stage to make any necessary adjustments to your cuts.

Once you have confirmed a perfect fit, remove the molding pieces. Apply a consistent bead of high-quality construction adhesive along the back of each piece of cove molding. Apply the adhesive about 1/8 inch in from the edges to prevent excessive squeeze-out. For longer pieces, apply adhesive in a serpentine or zig-zag pattern to ensure even coverage and a strong bond.

Carefully position the cove molding pieces onto the stair nosings, pressing them firmly into place. Apply even pressure along the entire length of the molding to ensure good contact with the stair nosing and to activate the adhesive. Hold each piece in place for a few seconds, or as recommended by the adhesive manufacturer, to allow it to grab.

For added durability, especially in high-traffic areas, you can reinforce the adhesive bond with small finish nails or brad nails. Using a brad nailer or a hammer, carefully drive 1-inch or 1 1/4-inch nails through the molding and into the stair nosing. Space the nails approximately every 12 to 18 inches, and ensure they are driven straight to avoid splitting the wood. Sink the nail heads slightly below the surface with a nail set.

Once the adhesive has fully cured and any fasteners are in place, address any imperfections. Use a quality wood filler to fill all nail holes, pressing it in firmly with a putty knife. Allow the filler to dry completely, then sand it smooth. Apply a thin bead of paintable caulk along any seams where the molding meets the stair nosing or adjacent trim to hide small gaps and create a smooth, finished appearance.

Once all filler and caulk have dried, thoroughly clean the installed molding and the surrounding stair nosing area to remove any dust or debris. If your molding is unfinished, now is the time to paint or stain it to match your desired aesthetic. Apply your chosen finish according to the product manufacturer's instructions. Multiple thin coats are usually better than one thick coat. Allow ample drying time between coats.