Beam Span Calculator
Look up built-up header spans for #2 Southern Pine from the published IRC Table 602.7 supplement.
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What this tool does
Look up built-up header spans for #2 Southern Pine from the published IRC Table 602.7 supplement. Scope: double (2-ply) headers of #2 Southern Pine, building widths 20/28/36 ft, ground snow 30/50/70 psf, two support cases. Other species use the multi-species IRC table values, which differ. This is a lookup, not a beam design.
How to use the Beam Span Calculator
- Enter or select built-up header / beam size (#2 southern pine).
- Enter or select what it supports.
- Enter or select building width.
- Enter or select ground snow load.
- Enter or select your opening / planned span in ft.
- Read the calculated result; change any measurement to compare alternatives.
Formula
table lookup in the published #2 Southern Pine supplement to IRC Table 602.7 (header spans by building width, ground snow load and supported load case)
- size
- Built-up header / beam size (#2 Southern Pine)
- support
- What it supports
- bwidth
- Building width
- snow
- Ground snow load
- opening
- Your opening / planned span (ft, before metric conversion)
Scope: double (2-ply) headers of #2 Southern Pine, building widths 20/28/36 ft, ground snow 30/50/70 psf, two support cases. Other species use the multi-species IRC table values, which differ. This is a lookup, not a beam design.
Worked example
For beam span calculator, the following measurements illustrate the exact method: Built-up header / beam size (#2 Southern Pine): 2-2x4; What it supports: roof; Building width: 20; Ground snow load: 30; Your opening / planned span: 5.
Inputs
- Built-up header / beam size (#2 Southern Pine)2 – 2×4
- What it supportsRoof and ceiling only
- Building width20 ft
- Ground snow load30 psf
- Your opening / planned span5 ft
Result
- Maximum header span3.25 ft
- Maximum span3 ft 3 in
- Your planned span5 ft
- CheckOpening EXCEEDS the table span — upsize the header or add support
Double-header spans, 28 ft building, 50 psf snow (#2 SP)
| Header | Roof + ceiling | Roof + ceiling + 1 floor |
|---|---|---|
| 2 – 2x4 | 2 ft 5 in | 2 ft 2 in |
| 2 – 2x6 | 3 ft 7 in | 3 ft 3 in |
| 2 – 2x8 | 4 ft 5 in | 4 ft 0 in |
| 2 – 2x10 | 5 ft 1 in | 4 ft 7 in |
| 2 – 2x12 | 5 ft 8 in | 5 ft 2 in |
Results explained
- Maximum header span
- Maximum header span from the formula above, expressed in ft before metric conversion. Scope: double (2-ply) headers of #2 Southern Pine, building widths 20/28/36 ft, ground snow 30/50/70 psf, two support cases. Other species use the multi-species IRC table values, which differ. This is a lookup, not a beam design.
- Maximum span
- Maximum span from the formula above. Scope: double (2-ply) headers of #2 Southern Pine, building widths 20/28/36 ft, ground snow 30/50/70 psf, two support cases. Other species use the multi-species IRC table values, which differ. This is a lookup, not a beam design.
- Your planned span
- Your planned span from the formula above, expressed in ft before metric conversion. Scope: double (2-ply) headers of #2 Southern Pine, building widths 20/28/36 ft, ground snow 30/50/70 psf, two support cases. Other species use the multi-species IRC table values, which differ. This is a lookup, not a beam design.
- Check
- Check from the formula above. Scope: double (2-ply) headers of #2 Southern Pine, building widths 20/28/36 ft, ground snow 30/50/70 psf, two support cases. Other species use the multi-species IRC table values, which differ. This is a lookup, not a beam design.
Frequently asked questions
For a 28 ft wide building, 50 psf ground snow, supporting roof and ceiling only: 5 ft 1 in. Add a centre-bearing floor and it drops to 4 ft 7 in (IRC Table 602.7 supplement, #2 Southern Pine).
A wider building puts more roof (and floor) area on the exterior wall — the header carries a wider tributary strip, so its allowed span shrinks.
Jack studs carry the header ends down to the plate. The full IRC table specifies their number for every cell (1–3 here); the lookup flags that you must take the count from the table for your cell.
No. This is the sawn-lumber header table only. Girders use IRC Table 602.7(2), and engineered beams (LVL, glulam, steel) follow the manufacturer's span tables.
Options: a 3- or 4-ply header (also in Table 602.7), an engineered beam, or a mid-span post. All need the full table or an engineer — do not extrapolate.