Replacing a Sill and Threshold

This story shows how to replace a door sill and threshold.


An exterior threshold takes a lot of abuse from foot traffic and weather, and it must be in good shape to keep the weather out. It can be replaced with a wood or metal threshold, either of which is available with a rubber gasket for sealing out the cold.

There is usually a sill below an exterior threshold. If the threshold is rotted, the sill probably is also. The sill is beveled on one side to drain water away from the house. Replace a sill using sill stock that has the same profile (shape) as the old sill. 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 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.

Prestart Checklist

2 or 3 hours

Circular saw or reciprocating saw, saber saw, hammer, chisel, nail set, tape measure, square, drill

Basic carpentry skills

Protect the floor with a drop cloth.

New threshold and/or sill stock, flooring adhesive, galvanized finishing nails, caulk

Replacing a threshold: Step 1

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.

Replacing a threshold: Step 2

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

Replacing a threshold: Step 3

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.

Replacing a sill: Step 1

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.

Replacing a sill: Step 2

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.

Replacing a sill: Step 3

Tap in the new sill to be sure it fits. Apply flooring adhesive and install the new sill with 12d casing nails.

What If... You are 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.

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