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What is a Jack Stud? Visual Guide



V Susan
Hi! I'm Susan. I am passionate about woodworking, general DIY and home improvement. If you'd like to connect with me or talk about something you like at mellowpine, drop me a mail at susan@mellowpine.com


What is a Jack Stud?

A jack stud is a short vertical structural stud used to support and anchor walls, floors, and ceilings. A sturdy header transfers the door or window’s weight to the jack stud. The bottom plate eventually receives the loads before they are transferred to the home’s foundation.

This article explains what a jack stud is and its significance in house framing.

Jack Studs in Framing

Jack Studs
Jack Studs

In a typical load-bearing wall, these are the structural components likely to be present:

Components of Load Bearing WallDescription
HeadersHorizontal beams that carry the weight of the material to the foundation below and are supported by jack studs.
King StudsFull-length studs that run from the sole plate to the top plate on either side of a door or a window.
Jack StudsShorter than king studs and support the header along both sides of a window or door opening.
Cripple StudsShort studs placed at an interval of 16 inches between the header and top plate, which are used as a base for nailing siding or coverings on the interior.
Important Components of a Load-Bearing Wall

Headers horizontally span over the door or window opening to support the weight of the structure above the opening.

King studs and jack studs support the header on either end and help distribute the load to the floor and foundation below.

Use nails to attach these studs to the header.

Jack studs are crucial since their length influences the header height.

Difference Between Jack Stud and King Stud

Jack Stud and King Stud
Jack Stud and King Stud

A king stud is a vertical building element placed on each side of a window or door opening, extending from floor to ceiling.

These studs strengthen an opening and improve overall structural stability.

On the other hand, jack studs are installed from the base plate to the lower end of a header.

For a particular wall, king studs will match the size of adjoining studs and are fastened similarly.

However, they frequently don’t fit inside the typical stud spacing of 16 to 24 inches.

In contrast, jack studs are typically positioned directly next to king studs within the opening, where they are secured together.

Moreover, when framing windows, it is common to divide jack studs into two to allow the window sill plate to pass through and end at the king studs on both sides.

This increases the window frame’s stability while reducing the requirement for extra support for the extremities of the window sill plate.

Furthermore, the king stud serves as the header’s ending point.

To reduce wall bowing, framing experts recommend using the straightest studs as king studs.

Additionally, king studs provide support and fasten drywall and casing.

Difference between Jack Stud and Cripple Stud

Although cripple studs are not structural, they are used for attaching siding and coverings inside walls.

They are placed at intervals of 16 or 24 inches and follow a standard wall stud pattern.

Additionally, cripple studs are crafted from the same stock as normal rafters and studs.

But they are trimmed to a shorter length.

Furthermore, with cripple studs, you can include additional framing above a door or window opening.

Also, they play a crucial role in a building’s framing as they serve as foundations for materials like plywood or drywall to attach to.

In contrast, jack studs support the header’s weight, whereas cripple studs are not necessary if the header reaches the top plate.

Benefits of Using Jack Studs in Construction

Any construction can benefit from the strength and stability that jack studs provide.

Moreover, they are a cost-effective and adequate solution to support walls and ceilings.

Jack studs can also assist in hanging doors and windows.

Additionally, they are simple to install and need few materials and tools.

Since the price is also reasonable, you won’t have to worry about exceeding your budget.

How Many Jack Studs are Necessary?

The width of the opening determines the number of jack studs to use in the framing.

Any opening that is more than five feet wide must have two or more jack studs.

The table below shows how many jack and king studs are needed at each end of an opening, according to IRC 2021.

Size of Opening(feet-inches)24-inch O.C Stud Spacing-Number of Jack Studs24-inch O.C Stud Spacing-Number of King Studs16-inch O.C Stud Spacing- Number of Jack Studs16 -inch O.C Stud Spacing-Number of King Studs
Up to 3′-6″1111
> 3′-6″ to 5′-0″1212

> 5′-0″ to 5′-6″
> 5′-6″ to 8′-0″1222
> 8′-0″ to 10′-6″2223
> 10′-6″ to 12′-0″2233
> 12′-0″ to 13′-0″2333
> 13′-0″ to 14′-0″2334
> 14′-0″ to 16′-0″2334
> 16′-0″ to 18′-0″3344
Total Number of Jack and King Studs Required at Each End of Opening(IRC 2021)

IRC also makes recommendations for the number of jack studs needed for headers and girders supporting one and two stories.

Headers and Girders Supporting SizeSpan(Building width-12 feet)Number of Jack Studs Required to Support at Each End
One floor only2-2×4 4-11
One floor only2-2×66-11
One floor only2-2-x87-91
One floor only2-2×109-21
One floor only2-2×1210-91
One floor only3-2×89-81
One floor only3-2×1011-51
One floor only3-2×1213-61
One floor only4-2×811-21
One floor only4-2×1013-31
One floor only4-2×1215-71
Two floors2-2×42-71
Two floors2-2×63-111
Two floors2-2-x85-01
Two floors2-2×105-112
Two floors2-2×126-112
Two floors3-2×86-31
Two floors3-2×107-51
Two floors3-2×128-82
Two floors4-2×87-21
Two floors4-2×108-61
Two floors4-2×1210-11
Maximum Spans for No.2 grade lumber of Douglas fir-larch, Hem-fir, Southern pine, and Spruce-fine-fir and the Required Number of Jack Studs(IRC 2021)

Jack Stud Installation Tips

Jack Stud Installation Tips
Jack Stud Installation Tips

Before starting the installation, measure the height of the opening to determine the length of the jack studs needed.

Next, choose jack studs made from strong, durable lumber, such as pressure-treated or kiln-dried wood, and cut to the required size.

Cutting the jacks to an accurate size is important, as oversized jack studs will not provide the required support.

On the other hand, if the jack studs are too small, they will not hold the load.

Place these jack studs vertically between the header and bottom plate using appropriate fasteners and use a level to ensure they are plumb.

Frequently Asked Questions(FAQ)

Are Trimmer and Jack Studs the same?

The term “trimmer stud” is occasionally used to describe the jack stud.

As part of the floor or ceiling construction, trimmers are inserted parallel to the main joists.

They support headers perpendicular to the primary joists.

What Height is Ideal for Jack Studs?

The height of jack studs depends on the design requirements of the structure.

Normally, a 6′-8″ tall door requires jack studs that are 81 inches long.

What are Header Hangers?

Header hangers are steel brackets that support headers above door and window openings.

Sometimes, they are used instead of jack studs to conserve the wood.

V Susan
Hi! I'm Susan. I am passionate about woodworking, general DIY and home improvement. If you'd like to connect with me or talk about something you like at mellowpine, drop me a mail at susan@mellowpine.com