How to Repair a Broken Door Jamb
Repairing a broken door jamb is not as hard as it appears, but the repair must be done correctly to maintain the security of the door. Door jambs can be broken by burglary, homeowners trying to access their home without their keys, or storm damage. Occasionally the wood may become damaged over years of neglect until the latch and strike plate damage the wood of the door jamb.
Most door jambs are constructed from wood which can be solid or finger-jointed. Some exterior doors, especially sliding doors, may be aluminum or aluminum-clad wood. This article will focus on wood door jambs and the repair procedures can be used for either interior or exterior doors.
When a door jamb is damaged, it usually occurs where the screws of the strike plate split the wood of the jamb. On exterior doors, the latch of the lockset or deadbolt lock can tear the wood of the jamb completely off the frame.
Tools and Materials
Wood drill bit, 7/8”
¾-inch Wood Chisel
Stiff Putty Knife or small pry bar
1x3 or larger piece of pine, at least 7 feet long
Drywall screws, 3-inch
Wood screws, 2 to 2 ½-inch
4d and 8d finish nails
Before repairing the wood of the door jamb you should remove any screws or strike plates that remain and pull out any protruding or bent nails. On exterior doors remove the weatherstripping on the latch side.
1. Remove the door casing on the latch side with a pry bar. If the casing is intact, you can save it and reuse it. Try to pull off the casing without splitting it and pull any nails out from the underside with pliers.
2. Use a circular saw to rip the jamb down along the door stop. If the stop can be removed, remove it first and then cut down the center of the jamb so that the stop will cover your saw cut.
Cutting down the jamb
You will not be able to cut all the way down to the floor or up to the head of the door. You will need to finish the cut with a utility knife or wood chisel.
3. Remove any remaining nails or screws from the framing.
4. After removing the wood check to see if the 2x4 framing is in good shape. Replace any fiberglass insulation that is missing between the framing and the jamb. Use a putty knife to gently stuff the fiberglass into the gap.
5. Measure the width for the new piece of jamb to be installed from the cut to the outer surface of the drywall. You can also measure the remaining jamb at the head of the door if the original jamb was not even with the drywall. Most door jambs are constructed with white or yellow pine. Pine 1x3 or 1x4 should be adequate for this repair. (In the picture below the width is 2 1/8”)
Use your circular saw equipped with a rip fence to cut the piece of pine down to the correct width. If you have access to a table saw, use that instead. After the wood is cut to width, use your circular saw or miter saw to cut it to the proper length.
6. Install the new jamb into place. You may have to trim the bottom edge to fit around the threshold. Use 3-inch drywall screws to secure the new jamb to the 2x4 framing. You may need shims to keep the jamb even to the edge of the door. You may also need to remove some drywall to insert the shims between the jamb and framing.
Trimming the bottom of the jamb
Checking the reveal between the jamb and door
7. Check the distance from the surface of the jamb to the edge of the door stop with a combination square. You can also use the square to check the reveal (gap) of the door to the jamb.
Checking the jamb with a combination square
8. Reinstall the casing onto the door jamb. Use the old piece to cut a new piece of casing or reuse the existing casing. Use 4d finish nails for nailing into the edge of the jamb and 8d nails for nailing the casing into the 2x4 framing.
9. Close the door and mark the location of the latch on the new jamb. Use a wood drill bit to drill a hole about halfway into the jamb for the strike plate. After drilling the hole, close the door and see if the latch lines up with the hole.
10. Place the strike plate over the hole and mark the location of the screw holes and the outline of the plate. Scribe the lines with your utility knife and then remove about 1/16 inch of wood inside the lines with the wood chisel. Install the strike plate with 2 ½-inch wood screws.
Installing the strike plate
11. Caulk the edge of the cut between the jamb and the door stop if you could not remove the stop. If the stop was removed, close the door and install the door stop with 8d finish nails.
Caulking the seam
12. Reinstall the weatherstripping.
Adding Strength to the Door
If you are worried about the security of your home you may want to purchase and install special door latch guards that are long pieces of aluminum that line up with your latches and are screwed into the jamb. They work by distributing the force of the latch over a larger area with multiple screws.
You can also remove the original screws from your strike plates and replace them with longer screws. This will not prevent the jamb from splitting, but may keep the door from opening completely. For doors with sidelights you will not be able to install long screws.