How to Install a Pre-Hung Door Jamb

Prehung jambs make door installation simpler.

Prehung doors are the easiest and most cost effective way to replace existing doors or install doors for new construction. Most of the technical details of door hanging are shortcut with a prehung jamb. They come with the hinges already cut out and attached and the door knob and lock holes pre-bored. Installing a prehung jamb requires common tools and a few shims and nails. Exterior jambs will also need screws for the threshold at the bottom of the door.

Things You'll Need

• Prehung door and jamb
• Tape measure
• Shims
• Level
• Hammer
• Nails
• Drill
• Treated Deck screws

Instructions

1. Prepare the door frame opening by removing any nails and other debris that might keep your door from attaching smoothly. Set the prehung jamb, with the door attached, into the wall opening. Use a tape measure to center the door between the vertical studs in the wall frame.

2. Tap shims into the gap between the top of the prehung jamb the bottom of the horizontal frame member above the door. Drive one nail up through the jamb header and the shims into the frame member above the door.

3. Add shims behind the top corner of the jamb on the hinge side of the door to snug it up to the stud. Place a level along the front edge of the jamb on the hinge side. Tap the bottom of the door in or out gently until the bubble in the level is centered inside its indicator. Add shims behind the bottom corner of the jamb and drive a nail through the jamb and shims into the stud behind. Nail through the shims you added at the top as well.

4. Wedge shims behind the top corner of the jamb on the handle side of the door and complete the leveling process for the jamb on the hinge side of the door. Open and close the door to check for proper operation. Tilt the jamb on the handle side of the door to make any needed adjustment so the door closes and opens properly. Nail through the jamb at the top and bottom of the jamb into the frame to secure it. Add shims and nails in the outside corners of the jamb header.

5. Fill the gap between the outside of the jamb and the frame with foam insulation backer rod for outside doors. This will help to seal the door from outside weather. Drive one 3-inch treated deck screw through each screw hole in the threshold at the bottom of an exterior door jamb. Drive the screw in until it pulls the threshold firmly down to the sill beneath.

References

• Trim Carpentry Techniques: Craig Savage, Taunton Press, 1989
• Home Tips: How to Install Door Jambs