How to Replace a Door Threshold and Sill

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.

House front door
Photo:

Michael Partenio

Project Overview
  • Total Time: 3 hours
  • Skill Level: Beginner

An exterior door 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, 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.

What You'll Need

Equipment / Tools

  • Flooring adhesive
  • 10d casing nails
  • Exterior wood putty
  • 12d casing nails
  • Sill cover, if desired
  • Hacksaw
  • Chisel

Instructions

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    Remove Old Threshold

    The threshold usually fits below the stops and against the jambs. To remove a door threshold, 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.

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    Mark the New Threshold

    Use the old threshold as a template to mark for cutting the new one.

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    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.

    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.

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    Remove Old Sill

    ​​Because it's nailed under the jambs, you'll have to cut a sill into pieces before removing it. First, cut out a large middle section, then chisel or pry out the smaller sections at the sides.

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    Use Old Sill as a 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.

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    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.

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    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.

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