Select the straightest studs you can find for framing; you will avoid problems later. Check each stud for a crown—a slight curve along its length—and install all the studs with the crowns facing the same direction. Build the wall with a bottom plate running across the doorway. This keeps the entire wall in one plane as you install it. Then you can cut the bottom plate out after the wall is installed. To make it easier to remove the bottom plate under the door, cut most of the way through it in the correct places with a circular saw. Editor’s Tip: A king stud is a stud that spans the height of the wall. A jack stud is a support, typically secured to a king stud, that supports a header for an opening—which would be needed for a door or window. A typical residential door is 32 inches wide and 80 inches tall, so the rough opening is 34 inches wide and 82 inches tall. Rather than rely on these dimensions, however, purchase (or at least measure) the door you will be installing before framing the opening. If you are in doubt about how big to make the opening, make it ¼ inch on the larger side. You can always shim a too-small door to fit, but a door that is too big for its opening is a nuisance to cut down. Project tip: When you are trying to tap a wall into position and get it plumb, it can be awkward to hold a level at the same time. Clamp a level to the side of one of the studs for hands-free viewing.
