Header Size, Opening Width, and the Stud Pack

The IRC R502.6 header table read by opening width and wall width, the smallest header that carries the opening, the king and trimmer stud pack with the cripples above, and the 3.5 in bearing line at each end.

The IRC R502.6 header table gives the maximum opening width for a doubled and tripled 2x8, 2x10, and 2x12 header on a 16, 20, and 24 ft wall, with the header supported on jack studs with not less than 3.5 in of bearing at each end. A header over an opening in a load-bearing wall is a framing, an inspection, and a permit item, and the LVL and steel answer is a manufacturer span table.

—The chosen header against the opening
—Maximum opening for this header
—Smallest header that carries it
—King, trimmer, and cripples
—Bearing and the jack studs
—Install, engineered, and the notes
How the math works
  • The IRC R502.6 header table (2-joist line): doubled 2x8 carries 5 ft 6 in on a 16 ft wall, 4 ft 8 in on a 20 ft wall, 3 ft 10 in on a 24 ft wall. Tripled 2x8: 8 ft 0 in, 6 ft 8 in, 5 ft 5 in. Doubled 2x10: 7 ft 1 in, 6 ft 0 in, 5 ft 0 in. Tripled 2x10: 10 ft 6 in, 8 ft 10 in, 7 ft 4 in. Doubled 2x12: 9 ft 2 in, 7 ft 8 in, 6 ft 5 in. Tripled 2x12: 13 ft 7 in, 11 ft 3 in, 9 ft 5 in.
  • Bearing: not less than 3.5 in of bearing at each end of a wood header (IRC R502.6), on the trimmer stud package, with the header seated on a lapped and nailed connection. A flush-mount header hanger with a manufacturer listing meets the bearing line with a listing, and a 1.5 in nail-through bearing does not.
  • The stud pack: 2 full-height king studs, 1 trimmer per side under a doubled header and 2 per side under a tripled header, and cripple studs above the header at 16 in on center with a head jack at each end. Cripple count = opening width in inches divided by 16, rounded up, plus 1.
  • Nailing (R602.3): 16d nails at 12 in on center on the edges of a built-up header and 6 in on center on the face staggered, with the plies aligned, the splices staggered, and the built-up member assembled with the spacer material the detail calls for.
  • Joist work around the opening (R502.8.2): a notch in a joist is limited to 1/6 of the member depth at mid-span and 1/3 at the ends, a bored hole is limited to 1/3 of the depth, the hole stays 2 in and more from the member edge, and a notched and bored joist over an opening is checked on the framing table span for the joist size and spacing.
Planning tool on the International Residential Code R502.6, R502.8.2, and R602.3 header and framing tables as adopted locally, on the 2-joist table line with 2 in nominal lumber at 16 in on center, SPF and S-PF lumber at the standard grade, and the standard field framing practice. The code edition in force, the local amendment, the permit, the framing inspection, the licensing requirement, the wind and seismic rules, the snow load, the engineered component requirement, the stamped drawing rule, and the special inspection requirement are jurisdiction calls. A load-bearing wall removal, a wall over a basement with a post and a beam, a pocket door on a 24 ft wall, a wide-span roof, a truss roof with a raised heel, a cathedral ceiling, a vaulted ceiling with a ridge beam, a garage door header on a 2x12 wall, a skylight, a dormer, a stair opening, a fireplace chase, a second-story addition, a shear wall with a strap, a moment frame, a let-in brace, an I-joist with a flange fill, a floor joist with a 6 in duct hole, a TJI with a 6 in hole, an LVL, a glulam, a steel flitch plate, a column with a capital, a beam with a girder, a beam bearing on a 4x4 post, and a post on a footing with a 12 in pier are all structural package questions with a stamped detail, and a licensed designer signs them. A 2x lumber header built from 2 in nominal stock, a 4x header, a 6x header, and a 8x header are the built-up and solid lines, and a 4x4 post with a 6 in by 6 in beam is a post-and-beam package with its own span table.

What size header for a 6 ft opening?

On a 16 ft wall, a doubled 2x8 carries a 5 ft 6 in opening and a tripled 2x8 carries 8 ft 0 in, so a 6 ft opening needs a tripled 2x8, a doubled 2x10 (7 ft 1 in), a doubled 2x12 (9 ft 2 in), and the smaller solid-sawn header in the table that reaches 6 ft is a tripled 2x8 (IRC R502.6).

How wide can a load-bearing wall be opened?

As wide as the header table and the load allow: on a 16 ft wall, a tripled 2x12 carries 13 ft 7 in, a doubled 2x12 carries 9 ft 2 in, and a tripled 2x10 carries 10 ft 6 in. Past the solid-sawn table the answer is LVL, a steel plate, and a flitch plate sized on the manufacturer span table with a stamp, and a removal over 12 ft on a load-bearing wall is a stamped job.

How many jack studs does a header need?

One trimmer stud per side under a doubled header and two per side under a tripled header, with 2 full-height king studs outside the trimmers and cripple studs above the header at 16 in on center with a head jack at each end. A 6 ft 8 in opening is 96 in wide, so the cripple count is 96 divided by 16, rounded up, plus 1, which is 7 cripples.

Can I use LVL instead of a built-up header?

Yes, and the LVL, a glulam, a steel flitch plate, and a 1-3/4 in by 9.5 in LVL are the engineered answers, sized on the manufacturer span table for the load and the span rather than the IRC 2x table. The LVL line carries a longer span in a shallower member, the bearing at the end is a 3.5 in line on the manufacturer detail, and the flange and the web of an I-joist at a bearing get a flange fill and a bearing stiffener.

Related tools

Joist span tableThe floor the header carries Framing lumber takeoffThe studs, plates, and headers for the wall Wall stud layoutKings, trimmers, and cripples in the layout Stair rise and runThe opening a stair cuts in a floor Rough opening framingThe opening the header spans