Jack Stud - Header Support Stud in Framed Walls Guide

A jack stud is the shorter vertical framing member that supports the header over a door, window, or other wall opening.

What It Is

A jack stud carries the load from the header down to the bottom plate or floor framing at each side of an opening. It works with the full-height king stud beside it, creating the built-up framing needed to transfer roof, ceiling, or floor loads around the opening.

Because it is a structural member, its size, quantity, and fastening depend on the width of the opening and the load above. Removing or cutting a jack stud without redesigning the opening can cause the header to sag or the opening to rack.

Where It Is Used

Jack studs are used in framed walls at exterior and interior doors, windows, pass-throughs, and large cased openings. They appear anywhere a header needs a direct bearing point at the side of the opening.

How to Identify One

Look at the side of a framed opening for the shorter stud that stops at the underside of the header. The taller full-height stud next to it is the king stud; the shorter support member is the jack stud.

Replacement

Replacement is needed when the stud is rotted, split, insect-damaged, badly cut for utilities, or removed during an earlier alteration. Structural wall repairs should restore the correct bearing path and may require temporary shoring while the damaged stud is replaced.