DIY Projects

How to Replace a Rotten Entry Door Sill

By: Danny Lipford
Rotten entry door sill.

Rotten entry door sill before replacement.

Door sills on entry doors can rot and deteriorate over time due to exposure to the elements. Use pressure treated or rot resistant wood when replacing door sill.

To Remove and Replace a Door Sill:

  1. Pull the rubber gasket out of the grooves on the metal threshold.
  2. Remove the screws holding the metal threshold in place.
  3. Cut the rotten door sill into pieces using an oscillating tool or circular saw.
  4. Remove the old door sill from beneath the door frame.
  5. Position the old door sill on the new sill, and trace around it.
  6. Cut the new door sill to size, and bevel the outer edge.
  7. Fit the new door sill in place under the door frame.
  8. Hold the new door sill in place with construction adhesive and fasteners.
  9. Caulk around the outside of the door sill.
  10. Paint or stain the new door sill.
  11. Replace the metal threshold and attach it with screws.
  12. Insert the rubber gasket in the metal threshold grooves.

Watch this video to find out more.

Further Information

Print   Video Transcript

If the threshold of an exterior door includes a wooden sill that has rotted, it’ll need to be replaced. The first step is to remove the rubber gasket, the screws, then the aluminum threshold.

The wooden part under the threshold is called the sill, and it usually extends under the door jambs so it has to be cut out. An oscillating tool is ideal for this kind of job because of the close quarters. Once you’ve cut out the visible part of the sill, you can pry out the part that extends under the jambs.

In this case there was a void in the concrete foundation which we filled with quick drying cement before replacing the sill. The new one should be made from pressure treated lumber to prevent future rotting. Use the pieces of the old one as a template to draw the outline for the new one if you can. Otherwise you’ll make a lot of measurements.

In order to match the profile of the door sill, you’ll likely need to bevel the outer edge and do some shaping with a sander. Once you attach the wooden piece with construction adhesive and fasteners, you can replace the aluminum threshold. It’s probably a good idea to use a new one. Now the rotten wood is gone and the entryway is sealed tight.



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