What should the header size be? I was thinking two 2×12.
One king and two jack studs on each side?
Do I need to build a temp support while installing the new header?
Doors – Replace a 36″ door with a Five ft slider on a two story load bearing out side wall
doorsframing
Related Solutions
International Residential Code 2012
Chapter 6 Wall Construction
Section R602 Wood Wall Framing
R602.7 Headers. For header spans see Tables R502.5(1) and R502.5(2).
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). 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).
1 king and one jack per side, assuming it's not an unusual load above. If your header has space above, make the jack continue up to the plate.
Only caution is that even though the 6" fill looks good on paper, the slightest fatness in your framing materials coupled with a tiny bit of "out of plumb", might mean your door is a tight fit. Buy the dryest 2x material you can find.
Best Answer
The 2x12's are good. 2x10's are calculated to be enough. Double jack studs are good. And definitely provide temporary support. This information is available on Table #
R502.5(2)P.