Adding garage doors

[airwayspilot]

I am adding a pair of garage doors to a metal pole barn building. Trying to determine the correct size header to build. I would guess 3 2x6s would cut it but I wonder if thats overkill because the structure of the building isn't really being affected by the holes being cut.

Anyone have a suggestion?

 

[6768rogues]

It depends on what it is supporting and the sizes of the doors. Gable or straight side? Between poles or cutting off poles? What is above that is supported? How will the header be supported? There is no one size fits all unless you go crazy and go huge.
If it supports nothing, I would use a 2x12 for the inner member so there is a large strong surface for mounting springs and an operator.

 

[Hot Rod Grampa]

If you are going between support columns most builders make a u shaped beam out of 2xs that fit between posts. Be sure to anchor horizontal 2xs with several verticals as the springs will be attached to them near the center of the door. The lumber will have to counter the torque of the springs on the tube based on the weight of the door.