The procedure for widening a doorway is not logistically complicated, but it does involve some demolition, and that can get messy. You have to remove part of the wall in order to widen the rough opening and to replace the header, which is the horizontal beam that extends along the top of the doorway and absorbs the weight of the roof or the ceiling. Drywall and wood paneling aren't difficult to cut back, but if you have to work with brick, cement, tile or stucco, you may need special tools and extra time to complete the job.
Pull the pins out of the door currently hanging in the doorway, take it down and set it aside. Pry the casing off of both sides of the door opening with a pry bar, then pry out and remove the jamb. Pry out the vertical jamb pieces first, starting at the bottom and working upward, and finish by prying out the top horizontal piece.
Draw a line on the drywall on one side of the door to mark the new width, extending it from the top of the doorway to the floor. If you are widening the opening in both directions, make a line on either side of the doorway. Cut along the line with a handheld cutting tool and remove the drywall. Cut carefully if you suspect there are electrical wires or plumbing pipes behind the wall.
Draw a horizontal line along the top of the doorway about 4 to 6 inches above the opening, cut along it and remove the drywall so you can replace the door header. The header is usually made from 4-by-4-inch lumber in a standard doorway, but it may be 4-by-6-inch lumber if the doorway is already wider than a standard one.
Work the blade of a reciprocating saw between the ends of the header and the studs to which it is attached and cut through the nails. In the same way, cut through the nails holding the cripples, which are the short studs between the header and the top plate of the wall. Slide out the header when you've cut through all the nails holding it.
Remove the studs framing the old doorway by cutting through the nails holding them to the bottom plate and cutting through the middle so that the pieces that remain attached to the top plate are the same length as the cripples that were attached to the header.
Cut back all the cripples to accommodate a thicker header if you are widening the doorway sufficiently to need it. You should use 4-by-6-inch lumber for the header if the wall is load-bearing or if the new opening is wider than 36 inches. Otherwise, a 4-by-4-inch header should be sufficient.
Cut a new header with a cicrular saw that is several inches longer than the new door opening and screw it temporarily to the cripples with 3-inch wood screws. The distance between the bottom of the header and the floor should be about 1 1/2 inches greater than the height of the door you plan to use to allow for the jamb and a gap between the door and the floor.
Measure the distance between the ends of the header and the bottom plate of the wall and cut studs to fit. Tap them into place, plumb them with a level and screw them to the header and the bottom plate with 3-inch screws. When you're done, the rough opening should be 2 inches wider than the door you plan to use.
Cut back the wall covering on the other side of the door flush with the new framing, then cut off the parts of the bottom plates of the wall that extend past the new opening with a reciprocating saw.
Install a new jamb, nailing it to the framing of the rough opening with 2-inch finish nails. Patch the walls around the doorway, if necessary, then install new casing.
Tips & Warnings
- If you are widening an exterior door, cut back the interior walls, install the new framing, then make modifications to the exterior wall to accommodate the new opening.
- If you just need an inch or two more clearance, you may be able to avoid widening the rough opening by replacing the door hinges with offset hinges.
- Check with your local building department if you're not sure what size header you need. If you use one that is too small, the roof may sag or the door opening may become distorted.
Things You'll Need:
- Pry bar
- Handheld cutting tool with multipurpose carbide cutting wheel
- 12-inch utility blade
- 4-by-4- or 4-by-6-inch lumber
- Reciprocating saw
- Circular saw
- 3-inch wood screws
- No. 2 Phillips bit
- New door jamb
- 2-inch finish nails
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