A homeowner who feels confident in proceeding with basic carpentry jobs may hesitate when confronted with building a wall that will have a door. Framing a door opening is not difficult, however, and anyone who can frame a basic wall can do it by following these steps.
Measure and cut two pieces of 2x4 lumber to the same length as the wall section you are building. These will serve as the top and bottom plates for your wall.
Get the rough opening dimensions for the door you purchased; it should be noted in the material that came from the manufacturer. Mark the door's rough opening width on both the top and bottom plates. Place additional marks on both plates, 1 1/2 inches and 3 inches on either side of the rough opening. The outside marks at 3 inches will be the location for the king studs, and the inner 1 1/2 inch marks will be the location for the jack studs that will frame the door.
Use 2x4 lumber and measure and cut the wall studs to the same length as your wall height, minus 3 inches. Nail the wall studs every 16 inches on centre between the top and bottom plates as shown in the diagram, except for the area you marked for the rough opening, king, and jack studs.
Measure and cut two additional studs to the same size as the previous wall studs. These will be the king studs. Nail them into place on the marks you made for them.
Measure and cut the two jack studs to a length of the height of your rough door opening, minus 1 1/2 inches. Nail the jack studs into place, inside the king studs and on the marks you made for them.
Measure and cut a 2x4 to the length that equals the distance between the king studs. Place it flat on top of the two jack studs and nail into place. This will serve as the header for the door.
Measure the distance from the top of the header to the bottom of the top plate. Cut a 2x4 to this length and place it as a cripple stud between the centre of the header and the top plate. Nail it into place.
Raise the wall into place and check that it is plumb. Screw the bottom plate securely to the floor and nail or screw the top plate to the structure above it. Your framed wall and door opening are complete.
Be sure there are no electrical wires or plumbing in the area before you nail the top plate into place.