Also be aware double or triple jack studs may be required based on the opening width and the load the header carries.
Header above sliding glass door.
A 36 door has a rough opening width of 38 so your header is cut at 41.
A typical header width with single jack studs is cut 3 larger than the rough opening.
However all the header sizing tables i have seen require 2 2x10 for this size opening.
We are installing a new 6 sliding glass door to replace an existing window.
Calculating window and door header requirements is complicated because they depend on a variety of factors including the size of the opening the weight of everything above it snow loads if it s an interior or exterior wall and more.
Doors in a load bearing wall that holds the weight of the house created by beams and trusses need a larger header than those in non load bearing walls.
If you have a floor above you ll need 2 2x6 s unless the building is 36 wide in which case you ll need 2 2x8 s.
So if you re on the top floor you can use 2 2x4 s unless the building is 36 wide in which case you ll need 2 2x6 s.
The longer the distance a header spans and the heavier the load it supports the more substantial it needs to be.
The header for a door is much like a bridge transferring the weight above it to the floor and foundation below.
Together the headers king studs and trimmers act as a system that transfers weight from above down and around the window and door openings to the floor and foundation below.
The existing header is 2 2x8 and is actually long enough for the new door.
For header spans see tables r502 5 1 and r502 5 2.