I'd use something like the second pic I posted. The next trick is to get the connections up to snuff. On one of the houses I'm working on, 1920's era, it is built that way. The few toenails are tired and there is a lot of split wood at many. I cut plywood gusset plates for each side of the rafter/joist joint, for connection specs it took a little cyphering. First, the codebook heeljoint table, at the end of the rafter span tables, gives the number of nails required in the rafter to joist connection based on building width, roof pitch, and snow load.http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_8_par027.htm?bu2=undefined
For a 20' wide 12/12 building in up to 70 psf snow country 6 nails at each end and at any laps in the joist will resist the tension. They are talking about 16 penny common nails through one 2x and into another. My drawing is stacked rafter on joist and plywood sideplates. We need to create an equivalent or better connection.
The (code approved) awc.org connections calc;http://awc.org/codes-standards/calculators-software/connectioncalc
is a good place to start.
Set it up in AllowableStressDesign for nails laterally loaded in single shear
To figure out their design strength with 16d commons enter them in SPF 2x's
...120lbs per nail, code called for 6, so they are calling it a 720 lb tension connection. (actual tension in that chord is much higher, code logic
... don't spare the nails)
Most people would be shooting a 12d box nail .128x3.25
I'd try 1/2" structure1 ply for the sideplate gussets...66lbs/nail
Try 3/4 ply ...80 lbs. More nails is going to be way cheaper than thicker ply.
Required connection strength was 720 lbs, divide by my 66 lb gun nail = 11 nails. I clamped our gussets on with 2 c clamps and nailed 6 shots from each side into the joist and 6 from each side into the rafter... 24 per rafter heeljoint total.
With that arrangement the ledger could be notched in on the outside of the studs, the compression side. It would be a good wall sheathing nailer there as well.
Seemed like a good idea at the time