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
In a typical load-bearing wall, these are the structural components likely to be present:
| Components of Load Bearing Wall | Description |
|---|---|
| Headers | Horizontal beams that carry the weight of the material to the foundation below and are supported by jack studs. |
| King Studs | Full-length studs that run from the sole plate to the top plate on either side of a door or a window. |
| Jack Studs | Shorter than king studs and support the header along both sides of a window or door opening. |
| Cripple Studs | Short 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. |
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.
You can use nails to attach the studs to the header.
Jack studs are crucial since their length influences the header height.
Difference Between Jack Stud and King Stud
A king stud is a vertical building element placed on each side of a window or door opening.
These studs strengthen an opening and improve overall structural stability.
King studs extend from floor to ceiling.
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.
They frequently don't fit inside the typical stud spacing of 16 to 24 inches.
Jack studs are typically positioned directly next to king studs within the opening, where they are secured together.
It is common to divide jack studs into two when framing windows 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.
The king stud serves as the header's ending point.
To reduce wall bowing, framing experts recommend using the straightest studs as king studs.
Around the door or window opening, 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.
Cripple studs are crafted from the same stock as normal rafters and studs.
But they are trimmed to a shorter length.
Using cripple studs, additional framing can be added above a door or window opening.
In contrast, jack studs support the header's weight.
Cripple studs play a crucial role in a building's framing as they serve as foundations for materials like plywood or drywall to attach to.
If the header reaches the top plate, cripple studs are not required.
Benefits of Using Jack Studs in Construction
- Any construction can benefit from the strength and stability that jack studs provide.
- They are a cost-effective and adequate solution to support walls and ceilings.
- Jack studs can assist in hanging doors and windows.
- They are also simple to install and need few materials and tools.
- There is no need to be concerned about exceeding your budget because the price is also reasonable.
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 Studs | 24 -inch O.C Stud Spacing-Number of King Studs | 16-inch O.C Stud Spacing- Number of Jack Studs | 16 -inch O.C Stud Spacing-Number of King Studs |
|---|---|---|---|---|
| Up to 3'-6" | 1 | 1 | 1 | 1 |
| > 3'-6" to 5'-0" | 1 | 2 | 1 | 2 |
> 5'-0" to 5'-6" | 1 | 2 | 2 | 2 |
| > 5'-6" to 8'-0" | 1 | 2 | 2 | 2 |
| > 8'-0" to 10'-6" | 2 | 2 | 2 | 3 |
| > 10'-6" to 12'-0" | 2 | 2 | 3 | 3 |
| > 12'-0" to 13'-0" | 2 | 3 | 3 | 3 |
| > 13'-0" to 14'-0" | 2 | 3 | 3 | 4 |
| > 14'-0" to 16'-0" | 2 | 3 | 3 | 4 |
| > 16'-0" to 18'-0" | 3 | 3 | 4 | 4 |
IRC also makes recommendations for the number of jack studs needed for headers and girders supporting one and two stories.
| Headers and Girders Supporting | Size | Span(Building width-12 feet) | Number of Jack Studs Required to Support at Each End |
|---|---|---|---|
| One floor only | 2-2x4 | 4-1 | 1 |
| One floor only | 2-2x6 | 6-1 | 1 |
| One floor only | 2-2-x8 | 7-9 | 1 |
| One floor only | 2-2x10 | 9-2 | 1 |
| One floor only | 2-2x12 | 10-9 | 1 |
| One floor only | 3-2x8 | 9-8 | 1 |
| One floor only | 3-2x10 | 11-5 | 1 |
| One floor only | 3-2x12 | 13-6 | 1 |
| One floor only | 4-2x8 | 11-2 | 1 |
| One floor only | 4-2x10 | 13-3 | 1 |
| One floor only | 4-2x12 | 15-7 | 1 |
| Two floors | 2-2x4 | 2-7 | 1 |
| Two floors | 2-2x6 | 3-11 | 1 |
| Two floors | 2-2-x8 | 5-0 | 1 |
| Two floors | 2-2x10 | 5-11 | 2 |
| Two floors | 2-2x12 | 6-11 | 2 |
| Two floors | 3-2x8 | 6-3 | 1 |
| Two floors | 3-2x10 | 7-5 | 1 |
| Two floors | 3-2x12 | 8-8 | 2 |
| Two floors | 4-2x8 | 7-2 | 1 |
| Two floors | 4-2x10 | 8-6 | 1 |
| Two floors | 4-2x12 | 10-1 | 1 |
Jack Stud Installation Tips
First, check if the jack studs are plumb and level.
Next, select appropriate fasteners and connectors for the task.
This is important because different types of studs require different equipment and materials.
Selecting appropriate jack studs is also vital.
Too big 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.
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.
Is it Possible to Cut Jack Studs?
Jack studs may occasionally be cut into two sections when constructing windows.
This is done so the window sill plate can pass through it and end at the king studs on either side.
A size reduction of more than 3/4 inch is needed to allow space for shims to square the door.
What Height is Ideal for Jack Studs?
Normally, a 6'-8" tall door requires jack studs that are 81 inches long.
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