16 garage door headers the garage and other window and door openings are prescriptive see figure r602 10 6 2 alternate braced wall panel adjacent to a door or window opening a minimum 3 x 11 25 net header size is required for opening from 6ft to a maximum 18 ft.
Garage door header on gable end.
Window door garage door headers supporting roof wall floor loads.
Very hard to figure as the fly rafter load would counter weight the second rafter in s up lift pivoting on the gable rafter.
They may suggest doubling up the trusses at the gable end in order to hand the header.
However it seems like picture one uses the most floor space.
Really kind seems to me like i ll save floor space by putting the doors on the gable end.
That would take care of the wind and seismic shear loads.
If the gable rafters are continuous and without any notches for the look outs out riggers the header would only support the wall framing above.
With notches the gable roof overhang loads and the gable rafter partial load.
Window door garage door headers supporting roof loads only.
For each application a pdf download is available.
Also see assumptions for table development.
A single flat 2 inch by 4 inch 51 mm by 102 mm member may be used as a header in interior or exterior nonbearing walls for openings up to 8 feet 2438 mm in width if the vertical distance to the parallel nailing surface above is not more than 24 inches 610 mm.
Two overhead doors ten foot wide plus a 3 foot man door need between 26 and 30 foot of linear space depending on how tight i want to go to the walls and between garage door bays.