Header & Lintel Sizing Calculator
Size wood headers over doors/windows and steel lintels for masonry openings.
Wood Header Sizing
Results
Recommended Header
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Total Load
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Tributary Width
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Max Moment
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Required Sx
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Note: Header sizes assume (2) members nailed together with 1/2" plywood spacer for 2x6 wall, or no spacer for 2x4 wall. Check deflection and bearing separately.
Steel Lintel for Masonry
Results
Recommended Steel Angle
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Masonry Weight
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Total Line Load
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Max Moment
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Allowable Fb
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Required Sx
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Note: For cavity walls, use two angles back-to-back or a loose lintel. Minimum bearing = 4" on each end. Paint or galvanize steel in exterior walls.
Built-Up (Multi-Ply) Header
Calculate section properties for multiple members nailed together.
Results
Bending Check
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Total Width
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Combined Ix
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Combined Sx
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Max Moment
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Actual fb
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Utilization
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Nailing: Use 2 rows of 10d or 16d nails at 16" o.c., staggered. Spacers should be glued and nailed.
IRC Table R602.7(1) - Header Spans
Prescriptive header sizes per IRC for various spans and loading conditions. Building width 36' max.
Key: Sizes shown are (2) members nailed together. LL = Live Load, SL = Snow Load, DL = Dead Load (assumed 10 psf floor, 10 psf roof)
| Opening | Roof Only (20 psf SL) | 1 Story + Roof | 2 Stories + Roof |
|---|---|---|---|
| 3'-0" | 2-2×4 | 2-2×6 | 2-2×8 |
| 4'-0" | 2-2×6 | 2-2×8 | 2-2×10 |
| 5'-0" | 2-2×6 | 2-2×8 | 2-2×10 |
| 6'-0" | 2-2×8 | 2-2×10 | 2-2×12 |
| 7'-0" | 2-2×8 | 2-2×10 | 3-2×12 |
| 8'-0" | 2-2×10 | 2-2×12 | 3-2×12 |
| 9'-0" | 2-2×10 | 3-2×12 | 4-2×12 |
| 10'-0" | 2-2×12 | 3-2×12 | Use Eng. Design |
Steel Lintel Quick Reference
| Opening | 4" Brick (Single) | 8" CMU | 12" CMU |
|---|---|---|---|
| 3'-0" | L3×3×1/4 | L4×3×1/4 | L5×3×1/4 |
| 4'-0" | L3.5×3×1/4 | L4×3.5×5/16 | L5×3.5×5/16 |
| 5'-0" | L4×3×1/4 | L5×3.5×5/16 | L6×4×3/8 |
| 6'-0" | L4×3.5×5/16 | L5×3.5×3/8 | L6×4×1/2 |
| 8'-0" | L5×3.5×3/8 | L6×4×1/2 | Use Structural Tee |
Notes: Based on 8' of masonry above opening. Sizes are single angles; use two back-to-back for cavity walls. Always verify with local codes and loading conditions.