Wood Ledger Attachment to High Profile Metal Siding

[bigmig]

I have a project where a prefabricated metal building (new construction) is getting a customer add-on wrap around shed roof.
The attached photo shows a very similar, installed and final condition.

The difference with my project is that the siding is a high-rib profile, metal panel, with 1. 1/2" ribs, on 12" centers. An incomplete section showing the roof-ledger-siding relationship is also attached.

I want to avoid metal building re-analysis with the prefab metal building engineers, who are more accustom to providing the metal building, and less in tune with re-calculating systems based on customer added roofs. I want to track the gravity load introduced by the ledger straight down to the foundation, by passing the metal building structure all together.

I can do this by infilling the bays between metal building frames and girts with a metal or wood stud system, appropriately braced for weak and strong axis stability.

The problem is this hi-rib, profiled wall paneling. Unless I cut the paneling, and install the wood ledger in the same plane as the wall panel, my ledger has this not-so-convenient 1. 1/2" air gap between the face of ledger and whatever it is I am using to lag the ledger into (NOT currently shown on my section)

If I cut the wall panel for ledger access, my ledger problem is now eliminated, but now I have this building wide penetration into the insulation and waterproofing system of the building envelope.

I know that answer is either leave the panel whole, or cut the panel, but I was wondering if anyone else came across this issue before and how they addressed it.

 

[jayrod12]

If you design your bolts correctly you could just block it out with 1 1/2" thick pieces. If you did 2 bolts per 12" and put an +/-11" long piece of lumber the same depth as your ledger.

Then you only have to worry about the bolt penetrations through your siding.

 

[PMR06]

Something like these brackets might work?

http://deckbracket.com/

 

[KootK]

1) I routinely use a similar detail that I loathe where I have to attach a ledger through drywall for goofy fire rating reasons. When the loads are substantial, I'll have the wall constructed of 4x4's and cantilever the lag bolts out through the drywall. You could do something similar here.

2) You could build your wall from 2x4 sill plates and 2x6 studs at 12" oc such that the studs are 2" proud of the sill plates on the exterior side. That way your studs could be pushed up snug against the troughs of the deck flutes. You'd only be able to sheath one side of the wall so some stability blocking might be in order. This would have your ledger in nearly direct contact with the wall studs. There may be insulation etc in the deck flutes that would preclude this solution however.

3) If the troughs of the deck flutes are wide enough, you might be able to install the ledger against the inside of the wall cladding. You would align your roof framing members with the deck flutes and make your attachment with concealed face mount hangers.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.