Hi tim
Thought l would throw my two bob's worth in. Built a few of these down under (Sydney) as they are becoming popular. Similar to the description given by ds hall. Basically use I beams ( hyspan) or LVL's straight onto level wall top plates. The underside of these serve as fixing for the ceiling sheets. The I beams ( depending on span) maybe upto 360mm deep or more?
On top of the I beams (that are level) place ply sheeting ( 16mm) would do. This allows the carpenter easy access and to work easily.
Then construct the parapet wall around the edge of the roof at desired height ie maybe 400mm depending on pitch and high point of roof. This is constructed as per normal stud wall.
For the roofing material we would use metal (clip Lok) sheeting that can be use d at a minimum 1 degree pitch. This would sit on stud walls of varying heights spaced at approx
900mm to 1100mm across the roof span in place of standard roof battens.
The lower stud wall or batten needs to be high enough to allow for a box gutter (say, 135mm) three lengths of 90 x 45 mm on top of each other. The upper stud wall (batten) maybe 300mm high etc depending on span.
The metal sheeting is fixed to the batten walls. Then it is a simple matter of flashing the parapet wall down onto the metal roofing.
Drainage pipes can run between rafters/ceiling joists, above eave/soffit.
Hope this helps.
Smitty
