Expert: Bruce E. Johnson - 3/22/2011

Question
I'd like to enclose the entrance to my 20'X20' double carport with an 18' garage door. The carport entrance is spanned using a double 2X12 fir rim joist with a 1/2" steel flitch plate and carries the weight of the rafters above and an asphalt shingle roof. Not exact, but the height of the supported roof is around 8' at the center (for ballpark roof pitch). If looking into the entrance of the carport, the left side is supported by the house, the other side is supported by three 4X6 solid posts (both corners and one in the center. The rear is also supported by posts. I'd like to build conventional framed wall for the front of the carport using three-stud corners, single king studs on either side of the future garage door header beam and double jack studs under the beam header for the garage door. This (garage door header) would go beneath the steel flitch rim joist and would bring the door height to 7' as needed. Since the garage door header is only there to create the 7' door height and would only support it's own weight, would double pine 2"X8" with a plywood flitch plate be sufficient? As the carport is currently, it has a 97.5" slab to beam height. In order to give me the 7' opening height I'd use the double 2"X8" header which would also have a top plate and cap plate above it as well as the 2" door jamb header. One last note---on either side of the 18' door, by the time the stud corners, kings, and jacks are installed, the sides of the door are practically solid studs. Should this be sufficient if enclosing the carport fully in the future?

Answer
Hi Wes, overhead garage doors are not supported by the header but by the rail and brackets on each side so if your existing roof structure is self supporting you really don't even need an additional header you can frame down the opening with conventional stub wall framing using short studs, a top and bottom plate and plywood sub sheathing to diaphragm the whole package together.  If you plan on installing an overhead garage door opener you can add a triple stud in the center of your stub wall for attaching to later.  You will need solid double or preferably triple studs at each side of the opening to eventually attach your track to.  You can do it your way as well if you desire and I wouldn't worry about the solid studs on each side of the opening but you will still need to cover them with something outside,  plywood sheathing and finished siding or T-111 siding, I wouldn't just use the solid studs as the finished exterior wall if that is what you were asking.  I can't see how this would affect your closing the rest of the room in in the future.  I hope this information helps please feel free to write again regarding this or other matters, sincerley bruce e johnson..bejohnsonconsulting.com