How To Install Interior Door Jamb Extension

Installing interior door jamb extensions is an effective and relatively simple way to adjust the width of a door frame to fit a new or existing door. This can be a necessary step if the door frame is too narrow for the door you want to install or if you want to add trim or molding to the door frame.

Here are the essential aspects of how to install interior door jamb extensions:

Materials you'll need:

Interior door jamb extension kit
Measuring tape
Level
Pencil
Hammer or nail gun
Wood filler
Caulk gun
Caulk

Instructions:

Measure the door frame: Determine the amount of extension you need by measuring the width of the door frame and subtracting the width of the door. Divide this number by 2 to get the amount of extension you need on each side of the door frame.
Cut the jamb extensions: Cut the jamb extensions to the desired length using a saw.
Install the jamb extensions: Place the jamb extensions on the inside of the door frame, flush with the top and bottom of the frame. Secure the extensions with nails or screws.
Fill any gaps: Use wood filler to fill any gaps between the jamb extensions and the door frame. Allow the wood filler to dry completely.
Caulk the seams: Apply a bead of caulk around the seams between the jamb extensions and the door frame. Smooth the caulk with your finger or a caulk tool.

Tips:

Use a level to make sure the jamb extensions are installed level.
Allow the wood filler to dry completely before caulking the seams.
Use a paintable caulk if you plan on painting the door frame.

Installing interior door jamb extensions is a relatively simple project that can be completed in a few hours. By following these steps, you can ensure that your door frame is the correct width for your door and that the installation is secure and professional-looking.