Second Storey Timberframe atop Milled Log House

[Glen Sutton]

I read this forum daily, and love the substance of the dialog, and the wisdom of the forum members.

My next framing project is a doozy; make over the family's beloved cottage.

Our house is a 24 x 34 foot milled log single-storey cottage. The logs are 6" thick and 8" tall with a double T&G at the horizontal joint. The ends of the logs fit into a vertical spline in the corner post. The house was built 25 years ago, so the logs are pretty much stable and we don't expect any vertical movement of significance.
Down the centre of the house there's a 6" x 12" summer beam supporting the roof. Half the roof trusses at the back of the house have a 5.5:12 roof pitch. The front half of the house has a 4:12 pitch and allows for cathedral ceiling in the living/dining room.
Our plan calls to remove the current roof/trusses/ceiling and add a second storey.
The difficult part is how to construct the second floor and its roof, using traditional timber framing. I imagine I would add an 8x8 top plate all around the top perimeter of the logs. Then tie my new joists on 4' centers to that plate, and tie them into the summer beam. Then deck with 2x6 T&G.
So, how should I construct the roof trusses ?  I think the gable end trusses would have their bottom chord tie in at the plate, post and rafter ends with English tying joint atop a stubby 4 foot post. I don't think there would be big rafter thrust to topple that post, and that it would only need braced for wind loads.
The truss mid-way down the house needs its bottom chord to be at floor level. That leaves the rafter to react its thrust onto the top plate and gives me an outward thrust.
What would be the traditional way to solve this problem ? With a new house construction, that post would go from main floor up 12 feet to the top plate. But in my case the original post goes only 8 feet, so the bent doesn't have the normal intended integrity.
One way might be to install a sister post inside the living space. That sister would take the bending moment and vertical load, but now I would need to figure out how to carry the vertical load down through the basement to footing. I'll have a hard time finding a clear way to bring those posts through the piping, wiring and partitions built over the years downstairs. So, I don't like that approach.
Anybody got any suggestions or alternatives ?

[PC-Urban-Sawyer]

I think this a good time to consult a qualified timberframe architect and/or engineer.

Good Luck!

Herb