If your door frame has become warped, skewed, damaged, or otherwise ineffective, you should replace it. Similarly, you may need to replace a door frame when installing a new door in an existing doorway. In either case, the same basic steps apply, and the process as a whole is relatively quick and simple.
Things You'll Need
- Tape measure
- 2-by-4 studs
- Reciprocating saw
- Circular or hand saw
- Hammer or nail gun
- Framing nails (10d)
Remove the old door and frame. In general, you should begin by taking off the trim/casing around the door (which can often be reused). Then use a circular saw to cut through the nails securing the old door unit to the surrounding frame, making it easy to slide the door out. Then, saw through and remove the framing studs that form the old rough opening for the door. You may need to remove a strip of drywall or paneling on each side to get access to the wall frame.
Measure the door (new or old) that will go into the new frame, and mark its width on the horizontal boards that form the top and bottom of the wall frame. Make marks beyond these width lines on each side at 3/8, 1-7/8 and 3-3/8 inches from the original lines. If possible, mark the height of your new door on nearby wall studs.
Use a circular saw to cut a pair of 2-by-4 studs to fit between the horizontal wall frame boards, and position them using the last set of marks you made in Step 2 (so their outside edges are 3-3/8 inches from your width lines). Nail them to both boards (top and bottom) by driving framing nails diagonally through them on each side.
Cut a pair of 2-by-4 studs to the height of your door, and position them next to the studs you just installed (so their inside edges are 3/8 inches from your width lines). Nail them to the studs and the top and bottom wall frame boards.
Measure the distance between the studs from Step 3, which should be 3-3/4 greater than the width of your doorway. Cut a single 2-by-4 stud to this width, lay it on top of the studs from Step 4 and nail it to both sets of studs. This is the header for your door frame.
Measure the distance from the header to the top of the wall frame. Cut a single 2-by-4 stud to this height, and place it vertically onto the midpoint of the header. Nail up through the header to anchor it in place, and nail diagonally through it into the top wall frame board. This is the cripple stud for your door frame.
If any portion of the bottom wall frame board extends into the doorway, saw it off so you have a completely clear opening. Your new door frame is now finished, and you can install your door and, as necessary, refinish the area around it.