The side of a door frame in which the lock participates is called the “attack side” of the frame. The attack plunger passes a strike plate on the jamb and maintains the door closed, locked or both. The power of a door closing hard repeatedly, or being forced open, can damage the door frame in the area of the strike plate. When this happens, it’s necessary to fix the frame until it gets worse and needs replacing. The job isn’t difficult for the normal do-it-yourself enthusiast.
Open the door and then stabilize it with a doorstop. Loosen and remove the screws that hold the attack plate in the surface of the door jamb using a screwdriver. Take the plate off and save the plate and screws.
Cut the bead of caulking in the vertical seam in which the inner border of the door casing meets the outer edge of the jamb using a utility knife. Cut the vertical seam of caulking in the outer border of the casing in which it matches the wall from bottom to surface.
Start at the top of the vertical slice of casing. Insert the tip of a wood chisel in the seam in which the caulking was cut. Tap the grip of the chisel with a hammer to drive the tip completely under the casing. Pry on the handle of the chisel to detach the casing from the jamb and adjoining wall. Repeat the procedure in several places along the border of the casing to remove the piece.
Pull any finish nails left behind in the edge of the jamb or face of the wall using pliers. Pull finish nails from the rear side of the casing to prevent damaging the surface of the slice, with the pliers or claws of the hammer.
Repairing the Door Frame
Inspect the border and face of the door jamb in the area of the strike plate. If the jamb is split, then squeeze wood glue to the crack and nail the border of the jamb using 4d finish nails. Normally, two nails around one inch apart to the outer edge of the jamb will hold a split together while the glue dries.
Remove the doorstop and shut the door. Inspect the gap between the edge of the door and the surface of the jamb in the area of the strike plate. If the gap is over 1/8-inch wide, open the door and stabilize it using the doorstop.
Put in a wood shim from the gap behind the jamb in the area of the strike plate. Tap the finish with a hammer to make a 1/8-inch gap between the surface of the jamb and the border of the door. Secure the shim in place using a 6d finish nail throughout the surface of the jamb above and below the area of the strike plate. The nails must be 1 inch from the edge of the jamb to prevent splitting the wood.
Put in a 7/8-inch flat wood piece in a power or cordless drill. Utilize the existing hole for the attack from the jamb for a guide and drill through the wood shim.
Reattach the piece of casing in the face of the door jamb using 4d finish nails in the inner edge from bottom to top of the jamb. Attach the outer border of the casing in the wall with 6d nails in 8-inch intervals from bottom to surface. Set the nails 1/16-inch deep for stitch using a nail set and the hammer.