floor truss?

[oldeerslayer]

This spring, whenever it gets here in WI, we are going to start a new 24 x 40 3 car garage. A 24 x 24 parking area in front with a 16 x 8 door offset to give lawn tractor space of about 6' on the left. In the rear and perpendicular to the front area will be a 16 x 24 repair area with a 2 post lift in front of a 10 x 8 door. I'll build a 2x4 dividing wall so I can heat just the shop when needed. All the exterior walls will be 12' because of the lift and simplicity of design. My building inspector says 2x6 24 O.C. is adequate and I like the idea one directly under each truss, which are standard 24-4/12 with 2' OH.
I should point out that in WI a building on Ag land does not require a Building Permit or any inspection. We built our timber frame home without any.
But since it is near the local village I got a permit for a "shed" to stay on the good side of the local officials, even though it will be used to store 2 tractors in the winter.
Anyway my question is about the header over the big door, which is on the GABLE end. I plan to place a STRUCTURAL ROOF truss 1-1/2" from the front edge and ad 2x4 nailers for the plywood. The framing up to 8' will be 2x6 to match the side walls. The plan is to use a 24' floor truss on top of the 2x6's and to also place it 1-1/2" back so that the nailers can continue down the front
of the floor truss. I'll enclose the back of the floor truss with 1/2" plywood bringing it all to 5-1/2" and to also essentially make the truss into a box beam.
Since the nailers will reach from roof deck to the top of the door, it should make for a very rigid structure.
Am I over building this? Should I just balloon frame the area from the door to the roof truss?
Please don't tell me I need LVL's or a 3x 2x12 header. This is a GABLE end below a structural truss. The sidewalls carry the entire roof load. I'm wondering if I even need the floor truss. I selected that as a header because it is lightweight. The way I see it LVL's or triple 2x12's have a problem keeping their own weight from sagging. All I am supporting is 8-10 3' 2x4's. The plywood will carry it's own weight while tying everything together.
Correct me if I'm wrong?

 

[Broncoman75]

around here the truss places all make gable trusses with just vertical members so I don't think they carry the load the same way/as much as a regular truss does. I think you may be overthinking it a bit as you say its just a gable you are holding up... unless you plan on brick on the front of the shed over the garage door, or some heavy *** garage door I would go with the "floor truss" or better yet ask the truss company about it, maybe they have a suggestion or can just make you another truss with a heavier chord you can sandwich to the gable truss to effectively make a header over the door.

 

[oldeerslayer]

They have gable end trusses here also. The manufacturers also specifically state they are not structural or load carrying. That is why I wanted to use a mid-roof structural truss at the end and simply set it back 1-1/2 inches, them add vertical 2x4 nailers every 2'. In effect I would be making a "structural gable end frame", which I could order from Midwest manufacturing, our local truss manufacturer. But it would be a special order and quite a bit more expensive.
Since I already have the trusses from a previous building that was enlarged, I can't see how adding the nailers would weaken the truss. In fact I would think if I nailed to every cord I cross, it would be substantially stronger. Also, carrying the nailers down to the floor truss and nailing to everything on it, the whole wall would be stronger, wouldn't it?

 

[DekeT]

The way I see it LVL's or triple 2x12's have a problem keeping their own weight from sagging. All I am supporting is 8-10 3' 2x4's. The plywood will carry it's own weight while tying everything together.
Correct me if I'm wrong?

You are wrong about the LVLs and trip 2x12s sagging, but otherwise what you plan can work.