Door thresholds keep the world at bay by providing a weather-tight seal. A loose threshold or damaged weatherstrip can allow water to leak under the door and damage flooring. Making repairs to your threshold in a timely manner can save time and money on expensive future repairs. Make certain that the threshold is snug against the floor and sealed around the bottom and edges, and that the weatherstrip is in good condition. Severely worn thresholds must be replaced.
Remove the weatherstrip from the channel along the top of the threshold to reveal the mounting screws. Use a screwdriver to tighten the screws. Replace any stripped screws with screws that are longer by ¼ inch and the same diameter. Choose screws with coarser threads if available. Take one of the old screws with you for comparison.
Use the original weatherstrip for comparison when choosing the right replacement parts. Cut the weatherstrip to length with a pair of tin snips. Fit the new weatherstripping into position by slipping the rubber edge under the lip of the threshold channel along the back of the threshold. Compress the weatherstrip to fit the opposite edge of the strip into the lip of the channel along the front of the threshold.
Caulk the base of the threshold along both the front and back edges and both sides against the door jamb with 100 per cent silicone caulking. Smooth the caulk with a dampened finger for a smooth finish.
Remove the screws from the top of the threshold. Pry the threshold up from the floor with a flat pry bar and lift it out of the door frame. Set it aside to be used as a template to mark and cut the new threshold. Scrape the old caulk from the threshold area with a metal scraper and sweep the floor to remove the debris.
Use the original threshold as a template and mark its outline onto the new threshold. Cut the ends of the threshold along the line with a jigsaw to fit against the profile of the door jamb.
Apply a bead of caulk inside the edge of the bottom of the threshold. Set the new threshold in the door frame and tap it into place using a rubber mallet.
Drill pilot holes through each screw hole in the threshold into the floor beneath with a 1/8-inch bit. Drive a 3-inch treated deck screw through each screw hole. Tighten the screws to pull the new threshold snug to the floor. Install the weatherstripping in the top of the threshold.