Cut a new length of flooring to fit snugly into the space of the old board. It doesn't matter what kind of saw you use to repair your hardwood floors; just make sure the cuts are perfectly square. After trimming the board to length, turn it upside down and use a chisel to chop off the lower lip of the grooved edge (photo 5). That allows it to fit over the protruding tongue of the adjacent floorboard. Test-fit the new piece. If it's slightly lower than the surrounding floorboards, shim it up with strips of kraft paper. Then remove the board and spread carpenter's glue on the tongues and grooves of the new and old pieces. Slip the new board into place (photo 6), protect it with a scrap-wood block and tap it down with a hammer. Cover the board with wax paper, then hold it down overnight with heavy books or weights. An alternative to gluing: Simply face-nail the board with 6d finishing nails. Bore pilot holes at a slight angle, then drive in the nails. Tap them below the surface with a nailset (photo 7) and fill the holes with wood putty. Lightly sand the entire board smooth, but be careful not to remove too much finish from surrounding boards. After finding a matching stain color by experimenting on scraps of flooring, stain the boards to match the original floor. Let dry overnight, then apply two coats of clear polyurethane varnish. If the old floor is unstained, just apply the polyurethane.
For example, moisture can be a factor, as variations in moisture can lead to gapping and warping. For this reason, installing hardwood flooring in full bathrooms is not recommended because of the fluctuating moisture levels. Follow manufacturer recommendations relating to moisture before selecting and installing hardwood. For more protection against moisture, use a moisture barrier. Denver Hardwood Floor Install
Glue down engineered hardwood, alternatively. If you don't want to nail down the boards, you do have the option of using adhesive to put engineered hardwood in place. It's a good choice, but won't last as long or be as sturdy as nailed down hardwood. The procedure is very similar to the nail-down process. Follow the adhesive manufacturer's instructions for installation and drying times. Hardwood Floors