How many jack studs for a 5′, 6′, 8′, 10′, 12′ & 16 foot opening depends on opening width, loads, construction requirements and building code.
There are two vertical structure member laying side by side to support the door opening of your garage door, window door and main door are king stud and jack studs. They are provided along the door in place of wall studs to ensure safely transfer of load to sill plate.
Typically, a jack stud is placed adjacent to a door opening and king studs placed adjacent to jack studs and the both are nailed together to ensure both stay in place.
What is jack stud
The jack stud is a vertical structure element shorter than the full-length king stud on each side of a window or door opening but critical for holding up the ends of the header that bridges the gap. The jack stud is sometimes called a trimmer stud.
A jack stud is a vertical structural element often made of wood timber that sits below and side of door opening and supports a header to transfer its loads downward to the bottom plate or sill plate and ultimately to the structure’s foundation.
Jack studs length determines the header height and is critical for rough openings of garage door, windows and doors. Typically, a king stud is placed adjacent to a jack stud and the two are nailed together to ensure both stay in place. Additionally, the jack stud is typically nailed from below through the bottom plate, and will be toe-nailed into the header above also.
Jack studs have many names, like many framing members, are known by a variety of names on a regional basis often called as shoulder studs or trimmers or trims. The width of the jack stud will match the size of the adjacent studs used for that particular wall and will normally be a stress-rated dimensional lumber.
Occasionally in window framing the jack stud will be cut into two pieces to allow the window sill plate to run through the jack stud and terminate on each side at the king studs. It is thought that this adds stability to the window frame while minimising the need for additional support for the ends of the window sill plate.
The jack stud is shorter than the full-length king stud on each side of a window or door or garage opening but critical for holding up the ends of the header that bridges the gap. The jack stud is sometimes also called as trimmer stud or shoulder studs.
In this article you know about how many jack studs do i need for a garage door that will help you selecting right size and their number to installation of door or opening. King, jack and cripple studs shall be of the same dimension and thickness as the adjacent wall studs.
Jack stud height
The height of a jack stud in framing construction is typically determined by the height of the opening, such as a door or window, and the header above it. In general, a 6′-8″ tall door requires jack studs that are 81 inches long, while a 6′-6″ tall door requires jack studs that are 79 inches long
The height of jack studs need to be 81″ for 80″ tall door. To determine the jack stud height just add 1 inch to height of door. For example, if your door height is 78″, just add 1 inch to it, so you cut 79″ height for jack stud.
We should always use two studs on each side of the door opening. The first will be continuous from the top plate to the bottom plate. This is called a king stud. The next jack stud will be cut to the height of your door plus 2-1/2″ and minus the thickness of the bottom plate 1-1/2″ as it will rest on top of this. So your jack stud height should be cut at 81″ for a 80″ tall door. Your header size is determined by the load it carries.
Formula to calculate jack stud height: height of jack stud = door height + top plate header thickness – thickness of bottom plate, 80″ + 2 1/2″ – 1 1/2″ = 81″, so, your jack studs should be typically 81 inches long.
When are double jack studs required
You may require 2-or-more jack studs when building a frame of opening larger than the 5 feet wide. The number of jack studs used in door or window framing is always directly related to the dimension (width and height) of the opening, which then correlates to the dimensions and weight of the header.
How many jack studs for header
The number of jack studs required for a header depends on the width and height of the door or window opening and the load it needs to support. Typically, you’ll need one jack stud on each side of the opening whose span is lower than 5 feet. However, for wider than 5 feet openings or heavier loads, you’ll require 2 or more studs on each side.
How many cripple studs to header
The number of cripple studs needed above a door or window header depends on the height of the opening and width of opening and header size. Typically, there are two cripple studs above a header, but for taller openings, additional cripple studs may be required for proper support.
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How many jack studs for a 5′, 6′, 8′, 10′, 12′ & 16 foot opening
In this article we explain total number of jack and king studs required at each end of an opening as per R603.7(1).
The number of jack studs required for a 3 to 5-foot opening need to be one on each side, while the number of jack studs required for a 6 to 12-foot opening need to be two on each side. Moreover, the number of jack studs required for a 14 to 16-foot opening need to be three on each side, while the number of jack studs required for a 18 to 20-foot opening need to be four on each side.
How many jack studs for a 3 foot opening
Typically, for a window or door opening that span 3 foot (36 inches) or less such as 30 inches, 32 inches, you will need 1 jack studs (trimmer) and 1 king studs at both end. So, for a 3 foot opening 1 jack studs (trimmer) and 1 king studs are required at each end.
How many jack studs for a 4 foot opening
In normal, for a 4 foot window or door opening, you will need 1 jack studs (trimmer) and 2 king studs at both end. So, for a 4 foot opening 1 jack stud (trimmer) and 2 king studs at both end are required which safely transfer loads downward to the bottom plate and ultimately to the structure’s foundation.
How many jack studs for a 5 foot opening
Usually, for a 5 foot window or door opening, you will need 1 jack stud (trimmer) and 2 king studs at both end. So, for a 5 foot opening 1 jack stud (trimmer) and 2 king studs at both end are required.
How many jack studs for a 6 foot opening
Typically, for a 6 foot window or door opening, you will need 1 jack stud (trimmer) and 2 king studs at both end. Thus, for a 6 foot opening 1 jack stud (trimmer) and 2 king studs at both end are needed.
How many jack studs for a 7 foot opening
Typically for a 7 foot window or garage door or opening, generally you will need 2 jack studs (trimmer) and 2 king studs at both end. Thus, for a 7 foot garage door or window or opening 2 jack studs (trimmer) and 2 king studs at both end are needed.
How many jack studs for a 8 foot opening
In general, for an 8 foot window or garage door or opening, you will need 2 jack studs (trimmer) and 2 king studs at both end. Thus, for a 8 foot opening 2 jack studs (trimmer) and 2 king studs at both end are needed.
How many jack studs for a 9 foot opening
Normally, for a 9 foot window or garage door or opening, you will need 2 jack studs (trimmer) and 2 king studs at both end. Thus, for a 9 foot garage door or window or opening 2 jack studs (trimmer) and 2 king studs at both end are needed.
How many jack studs for a 10 foot opening
Typically, for a 10 foot garage door or opening, you will need 2 jack studs (trimmer) and 2 king studs at both end. Thus, for a 10 foot opening 2 jack studs (trimmer) and 2 king studs at both end are required are needed.
How many jack studs for a 12 foot opening
In general, for a 12 foot garage door or opening, generally you will need 2 jack studs (trimmer) and 3 king studs at both end. Thus, for a 12 foot garage door or opening 2 jack studs (trimmer) and 3 king studs at both end are required.
How many jack studs for a 14 foot opening
Normally, for a 14 foot garage door or opening, generally you will need 3 jack studs (trimmer) and 3 king studs at both end. Thus, for a 14 foot garage door or opening 3 jack studs (trimmer) and 3 king studs at both end are required which safely transfer loads downward to the bottom plate and ultimately to the structure’s foundation.
How many jack studs for a 16 foot opening
Typically, for a 16 foot garage door or opening, generally you will need 3 jack studs (trimmer) and 4 king studs at both end. Thus, for a 16 foot garage door or opening 3 jack studs (trimmer) and 4 king studs at both end are required.
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How many jack studs for a 18 foot opening
Typically, for a 18 foot garage door or opening, you will need 4 jack studs (trimmer) and 4 king studs at both end. Thus, for a 18 foot garage door or opening 4 jack studs (trimmer) and 4 king studs at both end are required.
Conclusion:-
Typically for an 8 foot garage door or window or opening 2 jack studs & 2 king studs at both end are required. Thus, you will need 2 jack studs and 2 king studs for a 8 foot garage door or window or opening.