How to Replace a Metal Door Sill

Cut the caulk around the old threshold before removing.

Door sills, commonly known as thresholds or door saddles are the bottom plate that keeps the outside elements at bay. Typically, sills are made from wood, vinyl or anodized aluminum. The sill sits between the side jams and is attached directly to the wooden floor sill underneath. Replacement requires removal of the old sill, marking and cutting the new sill and attaching the new sill to the floor. It is a fairly simple procedure that requires common household tools and materials.

Things You'll Need

• Utility knife
• Pry bar
• Jigsaw and bi-metal blade
• Rubber mallet or hammer and wood block
• Silicone caulk
• Drill
• 3-inch treated deck screws

Instructions

1. Remove the original sill. Cut around the outer edge with a utility knife. Remove any visible screws in the top of the sill. You may need to remove the weatherstrip in the top of the sill to reveal the screw heads. Use a cordless drill driver set on reverse to remove the screws. Pry up the sill with a pry bar, starting at one end. Work the sill up from the floor and lift it out of the door frame.

2. Set the old sill on top of the new and use it as a template to mark the length and any notches at the ends of the original sill onto the new sill. With a jigsaw and bi-metal blade, cut the sill to length and cut out the notches so that the new sill matches the original.

3. File the cut edges of the sill down to smooth them out slightly. Set the sill in place, pushing one end of the sill all the way to the floor and working the other end down until it is seated against the floor. Use a rubber mallet or hammer and wood block if needed. If the sill refuses to set down fully, pull it back out, trim any faces that seemed snug and reinsert until you have a good smooth fit.

4. Remove the sill and run a thick bead of 100 percent silicone caulk around the bottom edge. Set the threshold back in place and tap it firmly down against the floor. Drive one 3-inch treated deck screw through each screw hole in the threshold until it is pulled securely to the floor.

References

• "Installing Doors and Windows": Tom Law, Jim Hall; Taunton Press, 1989
• Md Team: How to Install Threshold