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.
FAQ
Does header span depend on the load above it? Yes, significantly. A header supporting just roof load can span farther than one carrying an additional floor above it, which is why header span tables are organized by both span distance and the load condition (roof only versus roof plus floor).
See the Joist Span Chart and Beam Span Chart.