The approved header schedule gives the jack stud count by header span for the loading on this wall: up to 4 feet, one jack; over 4 feet through 8 feet, two jacks; over 8 feet through 12 feet, three jacks. Each end also requires one full-height king stud. At the 10-foot 6-inch family room opening you count two jack studs and one king stud at each end. What does each end of that opening still need?
- ANothing further; two jacks and one king satisfy the schedule at a span of this size
This comes from landing in the two-jack row, which stops at 8 feet. The opening is 2 feet 6 inches past that boundary, so the row does not apply.
- BOne additional king stud at each end, because king studs increase with span at the same rate as jacks
King studs run full height and hold the opening together; they do not carry the header reaction. Schedules generally hold the king count flat while the jack count climbs with span.
- CTwo additional jack studs at each end, because the schedule counts studs per face of the wall
Jack stud counts in a header schedule are the total at each end of the header, not a count repeated on each face of the wall. Doubling them adds material with no basis and can crowd out insulation and fasteners.
- One additional jack stud at each end, bringing each end to three jacks plus the full-height king
Why D is correct
Ten feet six inches lands in the row covering spans over 8 feet through 12 feet, which calls for three jack studs per end. Two are installed, so one per end is missing. The king stud requirement is a flat one per end and is already satisfied.
What this question is testing
Whether the candidate can find the correct row of a schedule when the value sits just past a row boundary, and whether the candidate keeps the jack requirement and the king requirement separate rather than blending them.
On the job
Wide openings at family rooms, patio doors and garages are where jack counts slip, usually because the framer cuts all his jacks in one batch for the whole house. The inspection is fast: read the schedule, tape the rough opening width, count the jacks in the pocket from inside the opening. Doing it before insulation matters, because adding a jack after drywall means opening the wall and reworking the window trim.
Memory technique
Jacks grow with the span; kings stay put.
Exam tip
A span sitting just past a row boundary belongs in the next row up; check the boundary before you count.
Where to look it up
IRC Chapter 6 headers and the number of jack studs required at header ends, plus the header schedule in the approved set.