IRC Header Span Table

Bookmarkable R602.7 grids by header size, building width, and snow — the inverse of the calculator

The header size calculator returns one recommended size for the opening you typed. This page is the full built-up schedule so you can ask the other question: what opening can this 2-2x10 carry? It is not the floor-joist grid (joist span table) and not the deck-beam grid (deck beam span table).

Have one opening? Skip the grid and get the smallest legal size.

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How to Read a Header Span Grid

Each row is a built-up size (2, 3, or 4 plies of a 2x). Each column is a load case: ground snow × building width for exterior walls, or building width alone for interior bearing walls. The number is the maximum clear span in feet and inches. The number in parentheses is NJ — jack studs required at each end for that cell.

You do not start at a 6 ft opening and scan down until you feel lucky. You pick the load column that matches the house (24 ft wide and 30 psf is the usual residential default), then read down until the span is at least the rough opening. The first row that makes it is the smallest header. That is the same logic the calculator uses; here you can see every neighbor cell, including how fast span falls off when snow goes from 30 to 50 psf or the building jumps from 24 to 36 ft.

Building width is measured perpendicular to the ridge. IRC allows interpolation between the 12, 24, and 36 ft columns. The calculator interpolates; this printed grid shows the three published columns so you can interpolate by eye. Do not interpolate snow by guessing a 40 psf column that is not in the code — use 50 psf or run the calculator’s 30/50/70 interpolator.

Species: IRC 2021 puts No. 2 Douglas fir-larch, hem-fir, Southern pine, and spruce-pine-fir on one grid. If your stamp is utility grade, or an older code tabulated SYP separately, this page is not that edition. LVL is not printed here; compare with the calculator’s LVL equivalent and then the manufacturer table. Material choice: sawn vs built-up vs LVL.

Exterior Bearing — Roof and Ceiling Only

Use this block for a one-story wall or the top story of a two-story where the header does not pick up a floor. Roof + one center-bearing floor is a different (shorter) block in R602.7(1); the calculator includes it. This page prints the roof-and-ceiling grid in full because it is the one framers look up most, and it is the grid you should not use if joists land on the wall.

Size	30 psf · 12 ft	30 · 24	30 · 36	50 · 12	50 · 24	50 · 36	70 · 12	70 · 24	70 · 36
2-2x4	4-0 (1)	3-1 (1)	2-7 (1)	3-5 (1)	2-7 (1)	2-2 (1)	3-0 (1)	2-4 (1)	2-0 (1)
2-2x6	6-0 (1)	4-7 (1)	3-10 (1)	5-1 (1)	3-11 (1)	3-3 (2)	4-6 (1)	3-6 (2)	2-11 (2)
2-2x8	7-7 (1)	5-9 (1)	4-10 (2)	6-5 (1)	5-0 (2)	4-2 (2)	5-9 (1)	4-5 (2)	3-9 (2)
2-2x10	9-0 (1)	6-10 (2)	5-9 (2)	7-8 (2)	5-11 (2)	4-11 (2)	6-9 (2)	5-3 (2)	4-5 (2)
2-2x12	10-7 (2)	8-1 (2)	6-10 (2)	9-0 (2)	6-11 (2)	5-10 (2)	8-0 (2)	6-2 (2)	5-2 (3)
3-2x8	9-5 (1)	7-3 (1)	6-1 (1)	8-1 (1)	6-3 (1)	5-3 (2)	7-2 (1)	5-6 (2)	4-8 (2)
3-2x10	11-3 (1)	8-7 (1)	7-3 (2)	9-7 (1)	7-4 (2)	6-2 (2)	8-6 (1)	6-7 (2)	5-6 (2)
3-2x12	13-2 (1)	10-1 (2)	8-6 (2)	11-3 (2)	8-8 (2)	7-4 (2)	10-0 (2)	7-9 (2)	6-6 (2)
4-2x8	10-11 (1)	8-4 (1)	7-0 (1)	9-4 (1)	7-2 (1)	6-0 (1)	8-3 (1)	6-4 (1)	5-4 (2)
4-2x10	12-11 (1)	9-11 (1)	8-4 (1)	11-1 (1)	8-6 (1)	7-2 (2)	9-10 (1)	7-7 (2)	6-4 (2)
4-2x12	15-3 (1)	11-8 (1)	9-10 (2)	13-0 (1)	10-0 (2)	8-5 (2)	11-7 (1)	8-11 (2)	7-6 (2)

Span in feet-inches. Number in parentheses is NJ (jack studs each end). IRC 2021 Table R602.7(1), roof and ceiling, No. 2 DF-L / HF / SYP / SPF.

Interior Bearing — One Floor

No snow column. A wider building still shortens the span because the floor tributary grows. Two-floor interior headers are a separate, shorter set of rows — do not use this block for a stacked bearing wall that carries two floors.

Size	12 ft wide	24 ft	36 ft
2-2x4	4-1 (1)	2-10 (1)	2-4 (1)
2-2x6	6-1 (1)	4-4 (1)	3-6 (1)
2-2x8	7-9 (1)	5-5 (1)	4-5 (2)
2-2x10	9-2 (1)	6-6 (2)	5-3 (2)
2-2x12	10-9 (1)	7-7 (2)	6-3 (2)
3-2x8	9-8 (1)	6-10 (1)	5-7 (1)
3-2x10	11-5 (1)	8-1 (1)	6-7 (2)
3-2x12	13-6 (1)	9-6 (2)	7-9 (2)
4-2x8	11-2 (1)	7-11 (1)	6-5 (1)
4-2x10	13-3 (1)	9-4 (1)	7-8 (1)
4-2x12	15-7 (1)	11-0 (1)	9-0 (2)

IRC 2021 Table R602.7(2), one floor only. Snow does not apply. Two-floor interior rows are shorter — use the calculator for that load case.

Footnotes That Change Jobs (and Are Not in a Single Calculator Cell)

0.70 unbraced factor. Tabulated spans assume the header top is laterally braced by perpendicular framing. If cripples sit on the header in a tall pocket, multiply 2x8, 2x10, and 2x12 spans by 0.70 or design the member. A 2-2x10 that shows 6′-10" becomes about 4′-9" unbraced. That single footnote is why this chart is not a copy of the calculator result screen: the calculator warns; this grid lets you apply 0.70 to every cell you might actually build.

Jack studs vs king studs. NJ is bearing under the header. Table R602.7.5 is a different count: full-height studs at each end of the header for wind. A 10 ft header in a 140 mph Exposure B wall wants three full-height studs even if NJ was 2. The calculator reports NJ. It does not size the shear-wall king package.

Single-member rows (1-2x6 through 1-2x12) exist in the code and are omitted here because they are rarely the right call on a bearing wall once the opening is past a closet. See IRC R602.7.1 and the comparison article.

Nonbearing walls are not on this grid. R602.7.4 is a flat 2x4 rule, not a span table. Using this chart on a partition over-builds; ignoring it on a bearing wall under-builds. Wall-type mistakes: troubleshooting. Method: guide.

This is a general guide transcribed from IRC 2021. Verify the adopted edition, amendments, and snow map. Not a permit document.

FAQ

Why print a table if the calculator already has the data?

Because the job question is often inverted. You have 2-2x10s on the truck and need to know which openings they still cover after the snow load changed. That is a grid, not a single output cell.

Where is roof + floor?

In the calculator load-case dropdown. Printing every R602.7(1) sub-table on one page repeats the code book; this page keeps the two grids people actually scan (exterior roof-only and interior one-floor) plus the footnotes the calculator cannot show as a matrix.

Can I use these numbers for a deck beam?

No. Wet service, joist tributary, and R507.5. Use the deck beam span table.

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Header Framing Gear

A header is only as good as the cut, the nails, and the jacks under each end. These are the tools that turn the table lookup into a wall that will not sag.