So, the master bedroom suite has been a real challenge but will hopefully reap the greatest rewards in the end. The initial take on the master bedroom was that it was definitely a late addition and certainly poorly built. The actual facts are more disturbing than the estimation.
First we found out that this 16' x 16' addition was added after a fire. The original house was 3 bedroom, 1 bath and in the SW corner bedroom someone had a woodstove (in a room that was only been 12' x 12' in the first place!). Well, as these things go, the front and side of the house caught fire but was put out before doing much structural damage; burnt halfway through the rim joist and just singed the gable truss.
So, the previous owner added a 16' x 16' addition, two feet away from the house but connected by a small corridor. Included in the addition was a 6' deep cellar with concrete floor, a cellar door under the deck, recycled rotten joists, a large unframed area in the floor for stairs to the cellar, a 5' x 5' picture window facing the road (the master bathroom had a 4' x 4' double casement window looking at the street), 1 wall that was not even sitting on the foundation, a deck with posts almost 16" in the ground, a cathedral ceiling using a 1x10 structural ridge beam, and a level valley in the corridor area of the roof that must have been a leaky spot from day one considering the 4" of tar that i chiseled out of it.
Of course all these design features created their own problems. The foundation bowed in on every wall, the worst wall bowing in almost 4". The floor joists sagged except the three in the center which were the most rotten so they got posts under them. This created a 2" hill in the center of the room. The stair framing was just plain dangerous, leaving a 3' x 4' unframed area in the floor spanned only by the plywood subfloor. The roof sagged 3" in the center and resembled a japanese temple. My favorite aspect was the picture window in the front. Nothing like giving the neighbors a view. The result was a total demo down to the footings.