A door can be hung in a hallway to section off one part of a house from another. This is particularly useful if the house is large and portions are closed off in discrete heating and air conditioning zones. By adding a hallway door an entire section can easily be closed allowing one part of the house to be warmer or colder than another. Doorways are also added for privacy and as buffers against sound in homes where the main living spaces are too close to bedroom areas. Adding a door is not difficult and with a pre-hung type of door can usually be accomplished in a single day.
Measure the width of the hallway at the point where you want to install the door. Usually, you will want to install as wide a door as possible to allow people to carry items easily through the door. Many hallways are 42 to 48 inches wide. Select a door that is 32 to 36 inches wide for an adequate passageway-sized door. Purchase a pre-hung door.
Move a stud finder across the ceiling where you want to install the door. Mark the ceiling joist locations with an X.
Cut 2, two-by-fours the width of the hallway. Place one board against the ceiling. If your ceiling joist is running parallel with the board, move your board so that it will be directly under the joist. If your ceiling joists run perpendicular to the board, position the board where you want.
Nail the board flat to the ceiling at the ceiling joint locations so that your framing nails go into the joist. Use two nails for every 12 inches of board. This board is called a top plate. Drop a plumb bob from the plate to accurately position the bottom plate. If your flooring is carpet you will need to remove portions of the carpet before installing the bottom plate.
Measure the length of the board and divide the measurement in half. Mark the center point. Divide the width of the new door in half and add 1 inch. Measure from the center point mark to the left using your divided door width measurement and mark the board. Measure from the center point mark to the right using the same measurement and mark the board. Line the board up with the plumb bob over the carpet.
Place painter's tape on the carpet next to the board. Tape away from the wall to your first mark on the left. Tape away from the wall to your first mark on the right. Remove the board. Tape across the small sections parallel with the wall on each side. Use a utility knife to cut through the carpet and pad in these taped areas. Use a rotary hand tool with a saw blade to cut the baseboard inside the taped sections. Remove the small tack strip inside the taped sections using a utility knife and claw hammer.
Cut the two-by-four at the left and right side marks. Nail the bottom plates to the floor using the plumb bob to line up the bottom with the top plates. Measure from the underside of the top plate to the top of the bottom plate and cut four boards. Place one stud against the left-side wall aligned with the top and bottom plate and level. Toenail the stud to the top and bottom plate with two nails at each end of the stud. Repeat for the right-side wall.
Measure from the cut inside end of the left-side bottom plate, to the left 1.5 inches and mark the plate. Repeat for the right-side bottom plate. Line up a stud on the left side of the line for the left-side bottom plate and toenail it in place. Line up a stud on the right side of the line for the right-side bottom plate and toenail it in place. These are called king studs.
Look at your pre-hung door. The door will have a rough-in height measurement noted on the packaging material. If there is no measurement, measure the framed height and add 1 inch. Cut two, two-by-fours to this height. Place one stud on the door side of the left-side bottom plate. There should be a 1.5-inch overhang on the plate board to the right of the king stud. Align your new stud against the king stud and nail the two studs together. Repeat for the right side.
Measure from the inside of one king stud to the inside of the other king stud above your short inside studs. Cut a two-by-four board to this width. Position the board on top of the short studs across the door opening to form a header. Align the boards and nail each end with two nails. Measure from the bottom of the top plate to the top of the header board and cut two cripple studs out of a two-by-four. Space the cripple studs evenly above the header and nail them in place. This completes the door framing.
Measure and cut drywall to cover your door walls. Use a utility knife and a straight edge to cut the drywall. Screw the drywall to the studs using a screwdriver and drywall screws. Place paper drywall corner tape along the ceiling and both wall corners on each side of the new wall. Apply joint compound with a wide drywall knife to attach the paper corners in place. Cover the dimples made by the drywall screws using joint compound and a wide putty knife to scrape off the excess.
Insert the pre-hung door in the opening. Use wood shims between the studs and the door jambs to level the door. Screw the door to the studs through the shims. Trim off the excess shims before finishing the wall and door.