How to Install Patio Door Sill Extenders

Most patio doors come with their sill already attached to their frame. If you set your patio door in the rough opening and the sill does not extend past the rough opening's threshold, you need a sill extender. Sill extenders come in a variety of lengths and sizes. They are available for purchase at your local home builder's store. Before you begin this project, make sure the sill extender you purchased is compatible with your patio door's sill.

Sawhorses
Silicone sealant
Caulk gun
Utility knife
Paper towel
1-inch screws
Drill
Phillips driving bit

Instructions

- 1
  Lay the patio door down on two sawhorses, with the exterior side facing up. Insert a tube of silicone sealant in a caulk gun and cut off the tip with a utility knife.
- 2
  Locate the two channels running down the patio door sill's length. Apply a 3/16-inch bead of silicone sealant in each channel.
- 3
  Line up the sill extender's ridges, on the top surface, with the channels. Slide the sill extender onto the sill until its edges match up with the patio door's sill's edges.
- 4
  Wipe the extra sealant, which the extender pushed out while you slid it down, with a paper towel.
- 5
  Position the provided sill spacer under the patio door's original sill. Line up the spacer's interior edge with the original sill's interior edge. Secure the sill spacer to the sill using 1-inch screws.
- 6
  Apply a bead of sealant over the seam where the original sill rests on the sill extender. Place sealant on the sill's edges, where the sill extender is inserted in the sill.

Doorway Options

How to Lay a Threshold on Concrete

Doors