Hi, I was wondering how difficult it would be to remove the roof on the back part of my house and add a flat deck up there. I have a picture of what I am proposing that can be seen at http://www3.sympatico.ca/911sc/House_rear2.jpg

Notice that I want to be able to keep the gable end so as to not disturb the look of the house too much.

That looks doable but you need someone on site to assess how difficult.