A header carries the load above a door or window opening. This chart gives typical maximum opening widths for doubled headers supporting one floor or roof — always confirm against code.
| Header (doubled) | Max opening |
|---|---|
| (2) 2×6 | up to about 4 ft |
| (2) 2×8 | up to about 5 ft |
| (2) 2×10 | up to about 6 ft 6 in |
| (2) 2×12 | up to about 8 ft |
Load changes everything. These assume a typical light load. Headers carrying two floors or wide roof spans must be larger or engineered. Verify with a span table or professional.
Estimates for planning only — confirm load-bearing headers with code or an engineer.
See the Joist Span Chart and Beam Span Chart.