Thresholds come in wood and metal, with a rubber gasket for sealing out the cold. Most exterior door thresholds also have a sill beneath them. If the threshold is rotted, the sill probably is too. The sill is beveled on one side to drain water away from the house. It fits tightly between wall studs and under the jambs and casing, so you need to cut it before removing it. You may also want to replace an interior threshold because the old one is unattractive or because new flooring on one side of the doorway calls for it. An interior door threshold rests on the floor with no sill under it. Installing a new threshold and sill will take between two and three hours. Protect your floors with a drop cloth before you begin, and make sure you’re comfortable with basic carpentry skills. Editor’s tip: If you’re installing a metal threshold, it is usually easier to cut the stop moldings to fit around the threshold. Cut the sill with a hacksaw. Use a hammer and chisel to cut through the stops.
