Identify the scope of the damage. Many scratches can be sanded, but deep gouges or broken planks will need to be replaced.
Wear safety glasses and knee pads for protection and comfort. To remove the broken boards, use a utility knife and a carpenter’s square to score a new end seam. Use a hammer and a very sharp chisel to further define a clean edge. Then, to create separation, angle the chisel and remove 1/8” of wood per pass. Work toward the end seam, but take care to not damage the wood on the other side.
Once the new end seam is fully defined, set a depth of 3/4” (or the depth of your floor) on a plunge saw or circular saw (for a cleaner job, a plunge saw with vacuum attachment is ideal). Cut the damaged plank in half lenghtwise. Caution: Cutting through existing nails may create sparks and is normal in this instance.
Use a pry bar to gently remove half of the cut plank. This will free up the remaining half, which usually slides right out. Take care to protect the tongues and grooves of the adjacent undamaged planks. Use the chisel to carefully remove any nailed remnants.
Continue the above steps as needed until all the damaged planks are removed.
Use a nail set to sink protruding nails or remove them completely using pliers.
Assemble several planks loosely over the space to get an overall view of how many new planks are needed and where to put new staggered end seams. Avoid “tangents”— this is when two end seams on nearby boards line up within six inches of one another. In other words, stagger the end seams as much as possible. This is mostly for aesthetics, but also helps for overall floor strength.
Working one board at a time, measure and mark for cuts. Use a radial arm saw or chop saw to make the cuts. In order to maintain tongues and grooves, cut a plank in two for easy insertion.
Tap and slide the new planks into the tongue and groove openings using a soft mallet. Once in position, use a finish nail gun to fasten. Insert three or four nails at a 45-degree angle into the notch of the tongue. Keep nails about two inches inside the ends of each plank.
For the last plank, use a table saw to remove the tongue and bottom half of the groove. Carefully set the blade depth and fence width on your saw before making the cut. Removing this wood allows the last board to drop into place.
Before inserting the last plank, place a few dollops of construction adhesive directly onto the sub-floor. Do not use wood or carpenter’s glue because it won’t allow the wood to expand and contract. Adhesive creates a permanent seal, but still allows for natural movement of the wood.
Use a soft mallet to gently tap the plank into position. Once set, complete the installation by top nailing two inches from the end seam and one in the middle. If needed, fill any large gaps with wood filler and let dry.