This project is nearly complete, just pending a final city inspection. After inspection the roof will be insulated and dry walled and railings for the roof top deck will go up.
I went with a general contractor because I'm not experienced in home building (I'm a manufacturing guy). The garage is also submerged on a sloped lot, so concrete walls as high as 8 ft were required, way beyond what I am comfortable taking responsibility for.
For the roof, we did wood trusses with the roof spaced slightly off them (2x4's going the opposite direction on top of the trusses and plywood on top of that). I put in several vents to ensure that any moisture can evaporate easily.