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Calculate the minimum header beam size needed for door and window openings. Get recommendations for dimensional lumber, LVL, and glulam headers based on opening width, load, and building conditions.
Interior rough opening width
Typically opening + 3" (leave blank to auto-calculate)
Total tributary width for load calculation
Check local building codes for snow load
Double 2x6 safely spans 4.3 ft
Based on 15 ft tributary width
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A header (or lintel) is a horizontal beam that spans across a door or window opening. It carries the weight of the wall, roof, and any floors above the opening, transferring that load to the supporting studs (king studs) on each side of the opening.
Headers are critical structural components that prevent the wall from sagging or failing above openings. The size of the header depends on:
Built-up headers made from standard 2x lumber nailed together. Cost-effective and easy to install.
Grade: #2 or better recommended
Manufactured products with consistent strength. Span farther than lumber with smaller depths.
Best for long spans or heavy loads
Maximum safe spans for common header types (50 lbs/ft residential load, roof only):
| Header Type | Material | Max Span | Best Use |
|---|---|---|---|
| Double 2x6 | Lumber | 8' 0" | Small windows |
| Double 2x8 | Lumber | 10' 6" | Standard windows |
| Double 2x10 | Lumber | 12' 0" | Large windows |
| Double 2x12 | Lumber | 14' 6" | Patio doors |
| Triple 2x10 | Lumber | 16' 0" | Garage doors |
| 3.5" LVL | Engineered | 14' 0" | Long spans |
| 5.25" LVL | Engineered | 18' 0" | Heavy load |
| 5.25" Glulam | Engineered | 20' 0" | Visible beams |
Note: Spans vary based on load. Always consult building codes and engineer for critical applications.
| Support Type | Min. Bearing |
|---|---|
| Wood stud (king) | 3.5" |
| Steel post | 3.0" |
| Masonry wall | 4.0" |
Bearing spreads load and prevents crushing
For a standard 4-foot interior door in a single-story home with roof only, a Double 2x8 or 2x10 Douglas Fir typically works. For two-story above, a Double 2x12 or Triple 2x8 is recommended. Always verify with local building codes.
LVL (Laminated Veneer Lumber) is engineered from wood veneers glued together. It's stronger, more consistent, and can span farther than solid lumber with less depth. LVL costs more but is ideal for long spans or heavy loads.
No, a single piece of 2x lumber is rarely adequate for headers. Built-up (doubled or tripled) headers are standard because they provide necessary strength and bending resistance. Single beams don't meet code for most openings.
King studs run full height from floor to top plate beside openings. Jack studs are shorter, running from floor to under the header, directly supporting the header's weight. This combination transfers the load to the foundation.
Headers should extend at least 1.5" (half the width of a 2x4) on each side beyond the opening rough opening. The standard rule is opening width plus 3 inches total (1.5" on each side) for proper bearing on king studs.
For large openings, heavy loads, or multiple stories, yes. Your building department may require an engineer's stamp. For standard residential openings, the calculator provides good estimates, but always verify with local codes.
Garage doors (9-16 feet wide) require larger headers due to wide openings. Typical requirements: Triple 2x10-2x12 lumber, or engineered beams like LVL or glulam. Snow load significantly increases requirements. Always consult codes.
Heavy snow loads significantly increase the load on headers, requiring larger beams. In cold climates with 40-60+ psf snow load, headers may need to be one size larger. Check your local building code for snow load requirements.
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