garage loft; ledger to ledger joists?

I am working up plans for a garage loft and seek some wisdom from the many wise folks here. Many humble thanks in advance.

I intend the loft to span the entire width of the garage. The garage is quite small spanning 11'4" from wall to wall. Each wall is load bearing and constructed with 2x4, 16" OC. In an effort to avoid installing posts and securing them to the garage floor, I am considering fastening ledger boards to each side wall and hanging from them joists to run across the 11'4" span.

Attached you'll find a simple illustration of the proposed plan. The scale is a little bit off but quite adequate for discussion I feel. The illustration shows just one side of the proposed loft. The same methodology would be applied to the other side of the loft. You'll see veritcal 2x4 wall studs with a doubled 2x8 ledger supporting 2x8 joists.

Since the drawing is not annotated, here are some details of the plan with a couple questions following -

* all lumber is douglas fir-larch structural grade.
* ledger board: doubled up 2x8 attached to the 2x4 wall studs with two 1/2" x 6" lag screws at every wall stud.
* joists: 2x8 16" OC attached to ledger board with double shear Simpson joist hangers via 10d common nails.
* floor: tongue and groove ply ( unsure of thickness )

justification for the doubled up 2x8 ledger: I want to fully receive a 10d common nail (3" length ) driven through the joist hanger and into the face of the ledger.


and finally a couple questions:

ledger to ledger construction: In all my perusing of the diy and construction sites, I have never seen this type of design used before. This suggests to me that I have steered myself in the wrong direction. A bit of an open-ended question - is this a sound approach? span and load calculations have been done and I know the 2x8 16" OC is actually quite overbuilt. Its just the ledger - ledger connection that I am concerned with.


lag screws: I am a bit fearful to use a lag screw to mount the ledger since nearly every resource I have found thus far suggests that lag screws are not held to any sort of manufacturing standards. As such, they have no strength ratings. Rough estimates of 60% tensile strength are about as good as it gets. Outside of a lag screw, however, what real alternatives exist? I don't see a Simpson strong tie that addresses this type of connection.

The joist hanger I am looking at recommends using 16d common nails into the face and 10d common nails into the joist (double shear so is toed in through the joist and ledger). Given that the ledger thickness is 3", I have opted to use 10d common ( 3" long ) nails as a substitute to the 16d common (3 1/2" long). Would it be better to use the 16d common nail into the face even though there would be 1/2" protruding from the back side of the ledger? I do not know the trade-off between the fully sunk 10d and the slightly protruding 16d.

Thanks for reading through and thanks even more should you choose to reply.
-brian