How would you build this?

[MushCreek]

I'm trying to figure out how to connect the porch roof to the main roof, and this is what I came up with. The main roof will be engineered trusses; the porch roof regular rafters. Not shown are the posts that hold the porch roof up; they will be steel posts with flanges welded on each end to handle both compression and up lift. The porch roof extends 12' out from the house wall. Snow load is 15#/sq ft, and wind load is 90 MPH. I'm thinking of bolting a ledger board to the house wall (ICF/concrete) to attach the ceiling rafters to. These would overlap the roof rafters. The roof rafters would attach to the main trusses somehow (overlap?). Since the roof rafters are over 20' long, I have a little stem wall where they would be spliced. This also greatly reduces the potential load on the roof trusses. Does this make sense? I'll have to work this out with the truss designer for the added load where the roof rafters attach. I think I have all of the potential forces accounted for- what do you think?

[ColchesterCabin]

Not sure of the height of the outside wall. I personally would be concerned not knowing where you are at to have a 2.5/12 pitch. Overall doesn't look too bad. Sorry I can't get past the roof pitch... 

[MushCreek]

I'm in SC, so ice dams are not a problem. 2.5/12 is the minimum recommended for the tin I am using, and since it is DIY, I can take extra pains to insure proper sealing.