I bought a house that appeared to have a garage with a vaulted ceiling with only 2 2x4 beams spanning the 24 foot distance between the walls. Upon closer inspection the garage originally had beams spaced every 4 feet that had been removed. One of the remaining beams is split. I need to repair this as we get some pretty heavy snow load in the winter. I am installing 2x6 joists every 4 feet that are supported with vertical supports going up to the rafters. I would like to install 2x4s with joist hangers perpendicular to the 2x6 joists to hang drywall from. There will be no storage space above. Does this sound strong enough? Or should I do 2x6 joists 2 feet on center?
There are so many things wrong in that picture..........?
A carpenters truss is 2 opposing rafters and a ceiling joist, tied at each end with 5-16D nails.
Standard framing in a garage is that they occur at 4'oc., no matter what the rafter spacing is, and as stated, they hold the place together. So I would continue to add them as necessary. Using 2x6 DF.
I would change the 2x4 collar ties too 2x6, change the screws used in the gusset plates from drywall screws too deck screws.
Adding 2x4s to the bottom side of an already overspanned member will guarantee an eventual failure.
The bottom member of the carpenters truss should be a minimum 2x6, however, 2x6 for a span of 24' is overspanned by 9', at 16"oc, let alone 24"oc.
Were it me, I'd just re-establih the carpenters truss's and install a T-bar ceiling and install the tiles that fit my needs.