MattM, Modern French houses are slung up super quick with blocks and internal dab on insulation bats.
However, this is Normandy and I have tried to stick to the Ancient traditional styles and methods where I can.
Drip edge never seen it here, maybe in the UK but not here. Gutter boards/fosists are not common in rural areas. As my old joiner used to say, "Gutter boards, fossits etc, keeps me working", but nowadays these are now PVC/plastic with the manufacturers doing 'traditional styles' gota laugh.
Sadly all my old true craftsmen friends, Architect's, real Stone Masons, Bricklayers, Joiners, Cabinet Makers are all dying, but most have been out here and had a good luck see.
Mostly saying, "I, traditional methods," and "you got some work on here boy".
My friend the Cabinet Maker used to say, " Look, If Chippendale would have had marine plywood, he would have b..loody used it".
All the gutters, downpipes here are Zinc, and are still produced at a reasonable price. Lead is not liked/ encouraged by the authorities here.
As original roof methods the tiles have a 2 inch overlap from the wood roof boarding and I get the slates drip to be central just above the top of the 6inch wide zinc gutter.
Again I use zinc ridge covers as traditionally done, I make my own as the French supplied ones are very wide and don't match the old, again I use stainless steel holding screws.
Zinc sheet is aaagggra horrible to work with as it tears and is problematic when soldering large sheets together, flat roofs etc.
This barn roof has no gable ends.
This is the overhanging roof of the barn Entrance, and yes those main oak beams are in good condition and cantilever just right. Posh look, the small original guttering is still hanging there.
And the other end, not a roof square edge anywhere.