Measure the height difference between the two different floors. Hold a measuring tape against the lower floor and measure up to the higher floor. Write this measurement down.
Determine the width of the doorway or transition area and write this measurement down as well.
Purchase an appropriate transition strip for the area. A “step-down” transition strip bridges the flooring difference in two uneven floors. This transition strip has a slow angle that slopes from the higher flooring surface to the lower floor.
Use the measurement made in Step 2 to mark the transition's width with a pencil. Place the wood transition strip on a miter saw and cut it to size if it's made of wood. If the transition strip is made of metal, cut it with a hack saw.
Screw the transition strip into place. Pre-drill the holes with a drill bit and drill. Secure the screws in place with a screwdriver. If you are using a metal strip, you are finished. Finish a wood transition strip by filling the nail holes in the strip with wood putty. Let the putty dry then lightly sand it smooth with sandpaper. Paint or stain the transition strip as desired.