2nd Floor Addition on existing Flat Roof of Workshop
I have building 12' x 16' stick frame all 2" x 4" built on 16 on center. Joist ceiling is 2" x 8" x 12' with them placed 12" on center. Yes I know it's over built for a reason. I want a second story, but I couldn't when I was constructing this accessory building last year. Building has flat roof with tar rolled on. Building is less than a 1 year old.
The foundation has 2' footers all the way around it. It's on a slab.
I'm working on the plan for the 2nd story on top of it. The staircase will be outside of building. The walls for the 2nd will not go the full 16', they will only be 12' long, so really I want a room on the 2nd floor that is 12' x 12' with a roof that's called " I believe hip roof."
My first question is can i leave the existing roof on the building, except where the 2nd floor is going to be nailed to it?
My second question is "Can I raise the floor about a 2" x 4" in height, so I can insulate sound barrier?"
The building already has been approved by building and electrical inspection, so I'm good there.
I really want to add this 12' x 12' with a small pation over looking the yard with the staircase on the outside of the building.
The pictures are of the framing when I was doing that last year and the finished building without the paint job.