How To Lengthen An Interior Door’S Jamb?

This video demonstrates how to install a door jamb extension on interior pre-hung doors. The process involves measuring the width and height of the door frame, cutting three pieces of wood equal to the length of both sides and the top, and arranging them to form a door frame. The first step is to choose the correct door and determine the door swing. Split-jamb interior doors come in various styles and sizes.

To install a door, measure the depth from the window to the inner edge of the finish wall material. Rip down the jamb material to the needed dimension and cut to length. Overlap the top with side pieces and back-flash the casing with flexible flashing to seal the joint between the jamb and trim. A strip of flashing with paper left on the exposed adhesive side should extend 4 inches beyond the trim.

When stepping the trim back to leave a 3/16″ reveal, step the jamb extensions back an 1/8″ to create the extension. Use a measuring tape to measure the length of the hinges and cut out the appropriate shape from the door jambs. Ensure the jambs are a good fit by holding a piece of 1″ to the jamb and ripping along the line using the wall as a guide.