Hi All
Here are some pics of my converted gable roof shed into a flat roll off roof. When in use the sliding doors are closed making it a little haven in the backyard.
The roof rolls very easily on four rubber castors per half. As the structure doesn't weigh much at all I have used 2x3 metre long shelving system angle iron for the runners because they had precut holes which allows me to padlock the roof in any position and were easy to attached to the existing walls of the shed where the gable roof had previously been attached. I also have 2x2 metre lengths of same ( 1 each side ) connecting the runners together to minimize twisting. The roof seals by simply lifting one half over the other in the centre so no flashing is required there. I used a rubber product for timber decking from Bunnings to make flashing for around the roof which I simply screwed to the wooden frame that I made from 42x36mm treated pine battens again purchased from Bunnings. Six padlocks secure the roof when it's not in use, 2 at the centre of each half and 1 at each end in the middle of the batten. We've had some pretty heavy rainfall lately and no leaks.
I have a few finishing touches to do such as installing power instead of running an extension from another nearby shed and I will probably line the shed with some insulating material before next summer. The roof is white coloubond which makes a big difference to the heat inside the shed compared to the steel that it was before.
p.s. It took a fair bit of trial and error to get it right but it is great for convenience instead of carrrying and setting up all my gear to image and no more sitting on a damp cold lawn all night.