At what width does a header need to be doubled?

At what width does a header need to be doubled?

• A. 1.2 m (3' 11")
• B. 1.0 m (3' 3")
• C. 1.5 m (4' 11")
• D. 0.9 m (3')

Answer: (A)

When a header carries loads from above, the bending moment it must resist grows as the opening width increases. To keep the header from bending too much and sagging, builders increase the header’s strength by using more cross-sectional area. In many residential guidelines, a single header is acceptable up to about 1.2 meters (roughly 3'11") wide. Once the opening reaches that width, doubling the header (two headers or a pair of 2x members with a spacer, or a similar engineered solution) is recommended to share the load and provide sufficient strength. So, for openings up to about 1.2 m, a single header is typically used; at 1.2 m and wider, a doubled header is the safer choice. The smaller widths listed would be well within a single-header allowance, while the larger width would usually require more than just a simple double header depending on loads and wall conditions.

When a header carries loads from above, the bending moment it must resist grows as the opening width increases. To keep the header from bending too much and sagging, builders increase the header’s strength by using more cross-sectional area. In many residential guidelines, a single header is acceptable up to about 1.2 meters (roughly 3'11") wide. Once the opening reaches that width, doubling the header (two headers or a pair of 2x members with a spacer, or a similar engineered solution) is recommended to share the load and provide sufficient strength.

So, for openings up to about 1.2 m, a single header is typically used; at 1.2 m and wider, a doubled header is the safer choice. The smaller widths listed would be well within a single-header allowance, while the larger width would usually require more than just a simple double header depending on loads and wall conditions.