Here are a few pics of the roll off I have been busy building and more to come. The roof will be 50mm thick polystyrene with colourbond on each surface here
I admire you craftsmenship Im the type that would just go out and pay someone to build something like that. Only because I could never trust my own extensive building skills (NOT).
You misjudge me Peter my mate who is a cabinetmaker+++ and works in my backshed is the person I have been 'helping' to do all this. I am a mere retired scientist. The design was a joint effort.
Bert, How are you planning to flash the center of the roof? or are you allowing enough overhang of the upper section so that rain couldnt possibly get in?
Correct AlexN the worst weather comes from the southwest (from the right side in the drawing) in Melbourne and the west half of the roof will shield the join. It is all under control. I do have further options with custom flashing to control any potential leakage.
Bit more done. The frame rolls easily with one hand. There will be 600mm of eave on the north side to keep the Sun off the wall in summer. Radiant heat is the problem in summer and the Solarspan should minimise this.
If you pack the north wall with batts before lining it then heat buildup from the sun will be MUCH smaller. Actually, it is worth insulating all of the walls and inserting some vents in the corners of the floor and some under your eves to keep moisture at bay while you are on the job.
lovely job bert the roof design is brilliant should work fine ,looks like you could use a bit of a chainsaw job on those trees behind the shed .
well done
hope you got a permit for that thing 
I suppose though, If they dont block anything you wish to look at/photograph, then dont worry about it...
