How to Replace an Exterior Door Threshold

Thresholds are the primary line of defense against the elements entering your home. Over time, constant foot traffic and exposure to rain cause these transition pieces to rot, crack, or lose their seal, leading to unwanted drafts and water damage in your subfloor. Replacing one is a focused task that restores both the thermal efficiency of your home and the structural integrity of your doorway. Done well, a new threshold creates a weather-tight bridge between your flooring and the door bottom. It requires precise measuring and a patient hand when seating the new piece against the door frame. Do not settle for forcing a piece into place; if it does not fit snugly, you will continue to battle moisture intrusion.

Get the door out of the way. Pull the hinge pins or unscrew the hinges to remove the door from the frame. Set the door aside on sawhorses or a protected surface to prevent damage while you work on the threshold area.
Lift out the old piece. Use a pry bar to gently lift the existing threshold from the sill. If it is stubborn, cut through the sealant line with a utility knife to avoid damaging the surrounding door jambs.
Make a clean slate. Scrape away all old caulk, debris, and rot from the subfloor or concrete sill. Vacuum the area thoroughly to ensure the new sealant has a clean, flat surface for proper adhesion.
Cut to exact fit. Measure the opening from jamb to jamb and mark your new threshold accordingly. Use a miter saw or handsaw to cut the piece, ensuring you account for the profile of the door stop and side casings.
Lay the sealant barrier. Lay two thick, continuous beads of high-quality exterior silicone sealant across the entire sill area. These beads will compress to create a watertight gasket when you set the threshold.
Lock it down tight. Press the threshold firmly into the sealant and drive stainless steel screws through the pre-drilled holes. Tighten them just enough to seat the threshold without bowing the material.