Measure your new door, and mark its dimensions on the sole plate (the 2 x 4 that forms the base of the wall frame) and surrounding studs. Next, mark the rough opening for your door frame, which should be 1 inch wider and 1/2 to 1 inch taller than your door unit to allow for shimming and caulking. Finally, measure and mark spaces for two 2 x 4 studs on each side of your door frame. Note that existing wall studs may already be in the proper place, or you may need to remove studs that fall within your rough opening.
Measure the height from sole plate to top plate (the 2 x 4 that forms the top of the wall frame), and cut two 2 x 4 studs to match. Position these "king" studs using the outermost marks on either side of your rough opening. Check the studs with a level, and then nail diagonally through them into the top and sole plates.
Mark the height of your rough opening on the king studs, and then cut two more 2 x 4 studs to match. Place these "jack" or "trimmer" studs next to the king studs to form the sides of your door frame, and then nail them to the king studs.
The size of the header, which forms the top of your door frame, may be determined by local building codes. If not, a good rule of thumb is to use a piece of 2 x 4 lumber for non-load-bearing walls, or two pieces of lumber ranging from 2 x 6 to 2 x 12 (depending on how wide your door frame is) with 1/2-inch plywood between for load-bearing walls. In either case, cut your header to the door frame width, set the header atop the jack studs, and nail it into place through the jack and king studs.
Short "cripple" studs will connect your header to the top plate and help to distribute the load supported by the wall throughout the door frame. Measure the distance between the header and top plate, and cut a 2 x 4 to match. Place the cripple stud atop the header midway between the two king studs, and nail it diagonally to the top plate and header. For wider doorways, create multiple cripple studs and place them every 12 to 16 inches.
If any nails, shims or other objects are sticking out from the surrounding wall and into your door frame, cut or remove them to create an unobstructed opening. Use a level and square to double-check your studs and corners, and adjust as needed by tapping with a hammer or using a pry bar.
Things You Will Need
- Tape measure
- 2 x 4 lumber
- Saw (reciprocating, circular or hand)
- 10d framing nails
- 2 x 6 or larger lumber (optional)
- 1/2-inch plywood (optional)
- Pry bar
- Plumb bob
- Save time and frustration by choosing a pre-hung door unit, which comes with the jambs and hinges pre-installed and perfectly in place.