A pent roof.

I had decided to build an extended pent roof. The extra height would dramatically increase the useful space.
To create a gentle slope from front to back we cut several 12in long sections of 3x2 and secured them vertically to the front ring beam at 3 foot intervals. Across the back ring beam we used  9in sections thus generating our slope. Approximately a 1:24 slope. I figured this would be enough to allow water to shed properly but not so steep as to require birds mouth joints for the rafters.
The lower ring beam was not entirely level so I adjusted the heights slightly and checked with a spirit level so when the upper ring beam was secured it  was level. 
I found the easiest way to fix these was to use little noggings of timber and 4in and 3in screws. Although noggings may not look particularly professional they do create a very stable and solid joint and can be made from your timber off cuts.
It is essential to drill pilot holes before fixing with screws, having a pair of cordless drills males the job much quicker, no swapping back and forth between drill bits and driver bits.
The upper ring beam was attached and we were ready for the rafters.