Because the front gable wall had been damaged when the original roof collapsed it was difficult to work out the angle of the roof. The front right corner of the barn had been rebuilt once before and it appeared that the pitch of the roof was different on each side of the barn.
I made a template roof truss and took it to France in 2m sections. From this template it was possible to cut the first 2 rafters at the correct angle.

Made in Sheffield - England! The initial template for the roof truss is made in a garden 600 miles from the barn.