How to Replace a Deteriorated Door Sill or Threshold

Examine the threshold or sill to see whether or not each end of it sits under the door jamb, or door frame. Its position determines how it can be removed.

Slide a small pry bar under the threshold if it does not fit under the door jamb, and place a small wood block behind the pry bar to protect the floor. Push down on the exposed end of the pry bar to lift the threshold. Repeat the procedure as you move the pry bar from one end of the threshold to its other end until the nails holding the threshold to the floor come loose. Remove the threshold.

Measure the dimensions of the threshold if it sits under the door jamb. The dimensions will help you cut a replacement piece to size later. Make two cuts around the middle of the threshold with a handsaw, and then pry up and remove the middle section of the threshold. Split the end pieces of the threshold using a hammer and wood chisel, and remove them. Pull the splinters from under the door jamb.

Measure and cut a new threshold to size using the old threshold's dimensions if the old threshold's ends were under the door jamb. If the old threshold did not sit under the door jamb, then trace around the old threshold on the new threshold, and then cut along the tracing.

Apply an even layer of silicone caulk on the area where you will install the new threshold. Put the new threshold on that location. Set a wood block over the end of the threshold, and hit the wood block with a hammer to drive the threshold into place. Drill pilot holes in the top of the threshold, and then drive nails through the pilot holes to secure the threshold to the wood below.