The semi-round edge molding installed on your baseboard where it meets the floor is known as quarter-round. Quarter-round covers small gaps between the baseboard molding and the floor and offers some aesthetic appeal. When replacing quarter-round, many contractors use a nail gun and compressor. However, most homeowners only require simple hand tools to nail quarter-round baseboard trim. It is important to make your angle cuts and dry fit the quarter-round before nailing it onto the baseboard.
Sweep the corners of the wall and along the wall edges to remove dirt and debris.
Place the quarter-round against the molding and butt it up to the corner or the wall if necessary. Start at one end and press the quarter-round molding tightly against the baseboard.
Position a 1-1/4-inch finishing nail at the middle of the molding two inches from the end. Hold the nail so it is nearly perpendicular to the floor. Hammer the nail through the quarter-round and into the baseboard with a hammer. The finishing nail is thin enough to not split the quarter-round and long enough to anchor the molding.
Continue nailing the quarter-round, placing nails every 12 inches along its length. Go back and place the tip of a center punch on each nail head. Tap the center punch with a hammer to countersink the heads into the wood.