Door Header Size Calculator 🔨

Header Beam Function and Sizing

A **header** (or lintel) is a horizontal beam placed over an opening (door or window) in a wall to support the vertical load from the structure above. The load is then transferred down through the **jack studs** (or trimmer studs) to the foundation.

Key Factors in Header Sizing

Header sizing is a structural calculation based primarily on two factors:

• **Opening Span:** The distance the header must bridge. As the span increases, the required header depth and/or material strength must increase.
• **Tributary Load:** The area of roof and floor structure the header must support. Loads are categorized as **Dead Load** (weight of structure) and **Live Load** (occupants, snow, wind).

Header Construction

In residential framing, a header is often constructed using two pieces of dimensional lumber (e.g., $2 \times 6$, $2 \times 8$) placed on edge, with a spacer (e.g., a piece of $1/2"$ plywood) sandwiched between them to match the width of the wall studs (typically $3.5"$ actual width for a $2 \times 4$ wall).

Example: A header made from two $2 \times 6$'s and one $1/2"$ spacer results in an assembly with a **$5.5"$ actual depth** and a $3.5"$ actual width, fitting perfectly within a $2 \times 4$ wall.