How to Extend a Doorway

Use a tape measure, stud finder and painter's tape to widen the doorway visually. Move the stud finder to locate the closest studs in each wall on either side of the existing doorway. Mark the stud locations with an X. Measure the height of the existing doorway and draw a horizontal line at the same height on either side of the doorway. Place tape along the outline of the new doorway. When possible your new doorway should end at a stud location.

Remove any existing moldings around the current doorway. Use a nailset to drive finish nails deeper into the wall so you can save the trim if you want to reuse it. Cut along any caulk seams with a utility knife and pry off the trim gently.

Draw a line down the existing baseboard at the new opening location using a carpenter's square. Cut the baseboard in place using a rotary tool with a saw blade attachment. Remove the extra baseboard. Measure from the floor upward 8 feet and mark. Draw a horizontal line across the new opening area at this mark. This will allow you to see your header situation on one side of the wall.

Turn off all electricity to the area. Cut the drywall along the inside or doorway side of the studs where your painter's tape is located and across your 8 foot high horizontal line. Use a shallow cut so you only cut the drywall and not any wires in the wall. Remove the excess drywall to expose the studs.

Look at the board immediately above the current doorway. If that board is a large beam, your wall is load-bearing and you will need to replace the header beam during your renovation. To support the wall during the removal and replacement of the beam, you will need to build a secondary support wall a few inches from the current wall. This is a serious issue. Call in an engineer to identify where to build the temporary wall and what size to make your finished header. If you only see one or two 2-by-4-inch boards across the opening, you can continue.

Mark the king stud on either side of the existing doorway with a cut mark even with the top of the existing 2-by-4-inch board header. The king stud is the first floor to ceiling stud near the doorway. Usually a shorter stud is sistered to the king stud that is holding the header. Mark any other stud in your new doorway opening area with the same measurement marks. Repeat for the other side of the doorway. Cut the king studs and each additional stud to height with a sawzall. Cut between the existing 2-by-4-inch board and cripple studs above the doorway with the sawzall and remove the existing doorway framing.

Use the existing studs where you cut your drywall as the new king studs on each side. Measure the old sister boards and cut two studs to this height. Nail the sister studs against each king stud using a framing nail gun and two nails every 12 inches. Cut 2-by-4-inch boards to replicate the former header boards. Measure from the inside of one new king stud to the other.

Position the new header boards over the top of the new sister studs. Toenail the header in place with at least two nails per board on each end. If you are using more than one 2-by-4-inch board, sister the boards together with nails every 12 inches. Nail the dangling cripple studs to the top of the new header boards with two nails in each end.

Cut the bottom plate next to the new doorway opening using a rotary tool with a saw blade. Pry up and dispose of the remains. Close in the exposed studs above the new opening with drywall. Cut drywall with a utility knife and straight edge. Screw the drywall to the studs with drywall screws. Cover the seams with flexible mesh tape and joint compound. Spread the compound with a drywall knife. Cover the heads of the screws and smooth away any excess compound.