I've got the frame done and inspected by Emily Cat :-).
I got the timber quantity just right, with enough scrap to make those noggins to add a bit of rigidity.
The floor will be 18mm OSB which should be give it even more rigidity.
Our garden shed is a similar size and uses much smaller timbers, mind if you sneezed whilst in there, it may well collapse. There's always a tension between going cheapskate or conversely over-engineering it. Hopefully I've got it about right.
The roof timber seems possibly rather flimsy, being 6mm ply over 2x1 " battens, but there will be a lot of battens and the roof will be skinned on top and underneath. The curve should add enough rigidity to take my weight whilst putting on the EPDM.
Dunno if I should actually anchor it to the ground. Will the curved roof act like an aerofoil and might I find myself coming in to land at Stansted Airport.
click... "This is Stansted air traffic control, to unidentified summer house, you are cleared to land on runway one... over ".
It is in a fairly sheltered corner, but we are near the top of a very slight rise which seems to catch the wind.