On 22/05/17 19:30, Bob Minchin wrote:

Having thought about it a bit more. You could add a substantial ridge
board and purlins each end of which is supported down through the end
walls. In that way you can get the Gambrel shape without excessive
forces trying to splay the walls as the roof weight is "hung" off the
ridge and purlins
If you can get the purlins just above head height, then it should allow
comfortable movement inside.

I agree...