This story shows how to frame for a new exterior door.
Once you've determined the location for a new entry door, check for obstacles in the wall. Often a quick look from the basement or crawlspace will tell you what's hidden inside the wall above. But expect the unexpected when cutting into a wall and work carefully to avoid damaging utility lines.
Water pipes or electrical cables can often be moved without a great deal of difficulty, but check with a plumber or electrician first. Drainpipes and heating or air-conditioning ducts are difficult to move; if one is in the way, you may have to relocate the doorway.
Also determine what sort of stairway you will need outside. By looking at an existing door's bottom in relation to the house's siding, you can tell how high the stairway will need to be. Consult manufacturer's instructions for the correct width and height of the rough opening you will frame. The method shown here minimizes drywall work.
Most of a day to cut a drywall opening, make a frame for a door, and cut the siding
Tape measure, stud finder, drill, flat pry bar, hand drywall saw, circular saw, reciprocating saw, level, framing square
Removing wall materials, cutting lumber and building wall framing
Determine that no electrical, plumbing, or duct lines are in the way, or plan to move the lines.
Framing lumber (either 2x4 or 2x6), header lumber (2x6 or larger, plus 1/2-inch plywood), 3-inch screws, 16d and 12d nails
Assemble a king-and-jack-stud combination. Cut the jack stud to the height of the rough opening, minus 1-1/2 inches (to allow for the thickness of the bottom plate). Cut the king stud to reach from the bottom plate to the top plate. Place the jack stud on top of the king stud and nail or screw the pieces together.
To construct a header, cut two (three with 2x6 framing as shown) pieces of 2x6 (or larger) to the width of the rough opening, plus 3 inches (to allow for the thickness of the two jack studs). Cut 1/2-inch plywood spacers. Working on the floor, stack the pieces with the crowns facing the same direction (see next step) and use a square to make sure they are aligned. Fasten the pieces by driving two 3-inch screws or 16d nails every 8 inches or so.
Check that the opening is square, level, and plumb. It need not be perfect, but it should be pretty close. If you have doubts set the door temporarily in place to make sure it will fit. If the opening is not square, you may be able to remove fasteners at the top and move the king studs over.