How to Replace a Door Sill and Threshold
Don't wait for someone to trip over your rotting entry to revamp your front door. Learn how to install a new door threshold and sill in just a few hours.
An exterior threshold takes a lot of abuse from foot traffic and weather—and it can only withstand so much. If your threshold is in rough shape, replace it.
Thresholds come in wood and metal, both of which come with a rubber gasket for sealing out the cold. Most exterior 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 it has to be cut before it can be removed.
You may also want to replace an interior threshold because the old one is ugly or because new flooring on one side of the doorway calls for it. An interior threshold simply 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.
What You Need
- Nail set
- Block of wood
- New threshold and/or sill stock
- Flooring adhesive
- 10d casing nails
- Exterior wood putty
- 12d casing nails
- Sill cover, if desired
How to Replace a Threshold
Step 1: Remove Old Threshold
The threshold usually fits below the stops and against the jambs. To remove one use a nail set and hammer to poke the nails all the way through. Then tap the threshold out using a hammer and a block of wood.
Step 2: Mark the New Threshold
Use the old threshold as a template to mark for cutting the new one.
Step 3: Attach and Secure Threshold
Test the fit of the new threshold. Apply flooring adhesive to the floor, slip the threshold into place, drill pilot holes, and drive 10d casing nails to secure it. Fill the nail holes with exterior wood putty.
Bonus: Installing a Metal Threshold
With 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.
How to Replace a Sill
Step 1: Remove Old Sill
Because it is nailed under the jambs, you will have to cut a sill into pieces before removing it. Cut out a large middle section, then chisel or pry out the smaller sections at the sides.
Step 2: Use Old Sill as Template
If the old sill pieces are intact, assemble them on top of the new sill stock and use them as a template. However, measure to be sure the overall length is correct.
Step 3: Fit and Install
Tap in the new sill to be sure it fits. Apply flooring adhesive and install the new sill with 12d casing nails.
Step 4: Install Sill Cover
If desired, protect and liven up a sill with a metal sill cover, which wraps around the front of the sill. Cut it with a hacksaw. Install a cover alone, or purchase a cover and sill combination.