A header is a horizontal structural beam installed above a door or window opening, spanning the gap where studs would otherwise be, carrying the load from above and transferring it down through the jack studs on either side of the opening.
Because removing studs to create an opening also removes their load-carrying capacity, the header takes over that structural role, redirecting the load around the opening rather than through it.
Header size and material depend directly on the width of the opening and the load it needs to support, meaning a wider opening or one beneath significant roof or floor load requires a correspondingly larger header.
What Does a Header Involve?
- Solid lumber, engineered lumber, or steel depending on the load
- Sizing calculated from opening width and load above
- Support from jack studs on either side
- Insulation considerations in energy-efficient designs
Why Are Headers Important?
An undersized header risks excessive deflection or even failure under the load it’s meant to carry, potentially leading to sagging above a door or window, cracked drywall, or in severe cases genuine structural concern. This is why header sizing is one of the more carefully checked items during a framing inspection, particularly for load-bearing walls where the consequences of an inadequate header are more significant.
Wider openings, like a large sliding door or a wall opened up significantly during a remodel, often require an engineered beam or even steel header rather than standard dimensional lumber, since the required strength can exceed what solid wood alone can economically provide.
Header vs. Header Jack
A header is the horizontal beam itself, spanning the opening. A header jack, or jack stud, is the vertical support beneath each end of the header, transferring its load down to the foundation, and the two work together as a coordinated system around any opening.