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Wood: Using 2x ledger in Conventional framing

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I typically specify a 4x thickness to any ledger designed. I did this
primarily because of the problems associated with cross-grain failures in
masonry and tilt-up concrete construction with the roof pulling away from
the wall mass without appropriate tension ties. I continued the practice of
specifying 4x (or 3x minimum) ledgers for wood framed construction inasmuch
as I felt it may be possible to create a cross-grain failure in a 1-1/2"
thick bolted connection even though the wall mass was much less than masonry
or concrete (better safe than sorry methodology). I justified my decision
based upon the fact that most framing is by flush mounted connections and
generally not tension tied directly to the studs. The actual tension
restraint is the 4x ledger lag bolted or thru-bolted to the studs or posts
and the withdrawl load allowed on the hanger. The capacity is rather low in
wood construction.

On a current project, the framer balloon framed a wall that I detailed to be
platform framed with a high and low diaphragm. The high diaphragm occurs in
a garage and spans almost 30 feet with plated trusses. The low diaphragm is
a corridor that spans less than 8 feet. The contractor wants to use a 2x10
ledger to the balloon framing with 3 - 16d per stud at 32" o/c. The more I
ponder this, the less problem I see with the connection and the use of a 2x
member. The gravity load is small (less than 160 plf combined live and dead
load), the shear is less than 0.186*160 or around 30 plf and the tension per
joist would be less than 32 lbs (0.3*80plf*1.33ft).

Is there any code requirment that stipulates a minimum 3x or 4x ledger to be
used in wood framed construction? Am I missing something here or is it still
an acceptable practice to use a 2x ledger for low capacity loads?

This must sound awfully elementary, but I've been used to playing it safe
for so long that I have forgotten if the code is any more conservative than
I am.

Dennis Wish PE