Posted By BillBraskey on 30 Jul 2016 11:07 AM
I would consider another factor: trailers.  If you have (or ever plan to have) a boat, camper, or utility trailer, these tend to be wider than all but the widest dually truck.  I restore classic cars as a hobby, and it sure would be nice just to back a trailer, with a car on top, directly into a garage.  Heck, if you are designing from scratch and have the option, make your opening >10' high and 20' wide.  Don't even bother looking at residential-targeted doors.  There is a vast world of commercial rollup doors that offer custom sizing, wind ratings exceeding anything residential, and roll compactly directly over the opening, allowing you to reclaim the ceiling space inside the garage.  Residential products generally suck.

Well sure, if money was no object then we'd all spec commercial products.

Posted By ronmar on 28 Jul 2016 11:19 PM
Lbear, you didn't answer if the wall with the garage door is the load bearing wall for the roof or not? If it is not the load bearing wall I agree with MTicf that you can make a very strong CC header with 36" of uninterrupted height to work with... Even if it is the load bearing wall, depending on the roof load numbers you need to meet, it may still be possible. What are your roof design requirements and the span of the roof joists?

It's not bearing the roof. The roof loads are low, around 20PSF snow load and around 20PSF dead load.

The glulam roof joists are 24 feet wide

Well if it is not bearing the roof load, an 18' span with 36" of height to work with should be no problem for concrete to span. The limiting factor may be the column to support this CC beam formed over the opening. How much wall is available on either side of the opening to support the beam across the top(distance to nearest corner)?