How to hang trusses below top plate of bearing wall
I'm working of a set of concept drawings for a new house in Phoenix before I hire a designer to polish and finalize them for review with the city. I'm stumped on an element of the design regarding hanging trusses and can't find a solution. I hope someone can help.
The house will have flat roofs and the area in question has two ceiling heights (11' and 13') and two corresponding roof heights (13' and 15') on either side of a 13 foot 2x6 bearing wall. The 2'x25' trusses for the higher ceiling/roof will sit on the top plate and how they are attached and braced seems pretty clear.
What's not clear is how to hang the 2'x25' trusses 2 ft down on the bearing wall to result in a ceiling height of 11ft and a roof height of 13' on the other side of the wall. I could use slightly taller trusses with a load point on the top chord but I'm concerned the drywall joint between the ceiling hanging on the bottom of the trusses and the wall will have problems over time as the trusses shrink and expand.
Can I simply attach a couple 2x8 plates to the wall and hang the trusses from them with standard truss hangers? I've not seen a description in the IRC how this plate attachment to the load bearing wall is to be spec'd nor have I found a hanger to reinforce the attachment of the plates to the wall. Just nailing them doesn't sound like it would be adequate. What's the best solution?