it comes down to whether the roof above is trussed or stick framed.....i'm amazed at this thread and mostly it's length. there is good information, but the idea of engineering is figuring out an answer by specifics, no wonder the thread is so long, there are no specifics. but from the original post, where is it in the code? i couldn't tell ya, but as an architect it sounds like there's no load on the wall. assuming trussed roof construction.....if this is so, the only real weight is from the truss down to the top of the door frame. a 7 foot door up to a 8'-6 or 9 foot ceiling would amass a load in the neighborhood of 3-4 lbs /sf...a 4in12 pitch over that 16' opening would be (guessing) 61 wopping square feet or a grand total of 195 lbs or 12.2 lbs/lin foot on the header(assuming roof load is taken by the truss). i weigh 195 lbs and wouldn't worry about standing on a 16 foot span of a 2x12. so two 2x12's with a 1/2" spacer to match the wall width absolutely doesn't scare me. even if we add in the roof overhang to this, it's adding an additional 58 lbs/lin foot. i'd have to look up the beam's carrying capacity to be sure...
but then again, my house has a central beam spanning 18'6 (3@2x12s hemfir) supporting ground, floor second floor and roof deck-1/2stick framed roof. no spacers either. and in 22 years it's deflected 3/8" at the center and no cracked drywall anywhere. so as for a gabled endwall with no apparent weight on it, i'd say a double 2x12 sounds good......but in the code, i can't support it from here and understand the trouble with finding it.
adding brick that's another animal, but brick isn't all that heavy +/- 29 lbs/sf additional. as for the steel lintel, luckily they don't hold up the brick except during construction so that weight is just part of the beam anyhow....but it could be possible, once again, i don't know the factors involved to say one way or the other.
fyi, architects can do engineering, however, it typically is only when it's a small part of the overall project and within our abilities. an example being, if i was asked to design a toll booth office building for a new toll bridge project, i would not be allowed to design the bridge too. but i could design the structure of the building, i could design the mechanical system and the lighting. likewise an engineer, who's asked to design a toll bridge complex would be allowed to design and stamp an architectural element like a toll bridge office building. i do my own engineering where i'm able and it has worked perfectly fine for many years. but i've noticed lately, code/building officials and township engineers(usually young kids out of college) have been asking specifically for an engineer's calculations, and many don't understand i am perfectly able to perform these tasks legally. i am not against people asking for more information and i give it, but there are times when i just shake my head and realize the person who's asking for it doesn't understand what's in front of them and i wonder how more information and calculation is going to make them understand it any better. but it does make sense to me and if they truly want to know how things are done, i'm willing to educate. but (to them, not you guys) please refrain from asking for an engineer when none is legally required.
