The rough opening is the hole in the framing. It has to be bigger than the door so the jamb fits, with room to shim it plumb and clear the finished floor. Check the instructions before you frame anything, because a manufacturer's number beats any chart, and exterior doors, pocket doors and bifolds all have their own.
Door rough opening chart
| Door | Rough width | Rough height | Header length |
|---|---|---|---|
| 24″ × 80″ | 26″ | 82 1/2″ | 29″ |
| 28″ × 80″ | 30″ | 82 1/2″ | 33″ |
| 30″ × 80″ | 32″ | 82 1/2″ | 35″ |
| 32″ × 80″ | 34″ | 82 1/2″ | 37″ |
| 36″ × 80″ | 38″ | 82 1/2″ | 41″ |
Header length is the rough width plus 3″, because the header sits on a 1 1/2″ jack stud at each end. For a 96″ door, use the same widths with a rough height of 98 1/2″.
Where the extra space goes
The 2″ in width covers a jamb about 3/4″ thick on each side and leaves roughly 1/4″ per side for shims. The extra 2 1/2″ in height covers the jamb head, the shim space, and flooring plus a gap under the door. If the floor will be thick, like tile on a mortar bed, add that thickness.
What goes around the opening
- King studs run full height, plate to plate, at each side. Table R602.7.5 sets the number by header span and wind speed, and a door up to 4 feet wide takes one each side.
- Jack studs sit inside the kings and hold up the header. For our 82 1/2″ opening they're 81″ long, because they stand on the 1 1/2″ bottom plate.
- The header spans the opening. In a bearing wall, the size comes from IRC Tables R602.7(1) and R602.7(2). In a nonbearing wall, R602.7.4 says no load-bearing header is required.
- Cripples fill the space between header and top plate, on the regular stud layout.
Framing a door opening
- Mark the center of the door on the plates. Measure half the rough width each way, then 1 1/2″ out for each jack and another 1 1/2″ for each king.
- Frame the kings first, nailed through the plates like any other stud.
- Cut the jacks and nail them to the kings. Stitch them together up the length.
- Set the header on the jacks and nail through the kings into its ends.
- Add cripples above the header.
- Cut the bottom plate out of the opening last, after the wall is standing and fastened. Left in place, it holds the wall square while you lift it.
Before hanging the door, check the opening with a level and a tape, because the door will show any twist in the framing. Measure the width at the top, middle and bottom. Measure the height from the subfloor at both sides.
Adding doors to the framing calculator gives you stud counts and header lengths for the whole wall, and the wall framing guide covers the rest of the build.