Wow. I opened a real can'o'worms here.

With reflection, one significant different is the layout method. Square rule is unheard of here, and when you start explaining to French carpenters about housing almost every joint they look at you like you're crazy.



The above is an example of a classic modern french roof ("charpente traditionelle". As apposed to "charpente industrielle" which refers to stick-frame trusses). I worked on a near identical structure with the author of the above image. In 5 days we lifted (by hand) all the timber to the 1st floor. Laid out and marked everything. Cut the joints and mortises (draw bored pegs), and raised (with the aid of a crane which we pushed to its limits) 3 frames, and ridge beam (Davy installed the purlins and rafters later on his own as I was only on a 1 week work placement with him).

To explain, the French still draw out a 1:1 "épure" on the ground, position the timbers on it, and mark the positions of the various joints by consequence. So for that frame we retraced the épure (which had faded a little over the weekend), then laid out our timbers using offcuts as spacers. Davy then marked out the various joints and the two of us cut them. The timbers for each truss were then test fitted over the épure, adjusted if necessary and the tenons were marked for draw boring. Finally the tenons were bored, and all three trusses were built in a stack ready to be lifted. From memory we probably spent at least 1 day moving wood up to the first floor. And we spent 1 day with the crane lifting the frames into place. So that leaves 3 days (21 hours) in which we laid out, marked up, cut, test fitted and assembled the structure.

Heavy timber construction, ie. Timber Framing is nearly unheard of here. Our house is considered bizarre by most people who see it. Standard construction is a 1 1/2 storey blockwork structure with gable ends onto which in most cases a stick frame roof is nailed into place, but in which some clients demonstrate their taste for quality by commissioning a charpente traditionelle. And even then, rarely is much of that structure exposed to the inside, the insulation generally occupies the depth of the purlins leaving just a few braces and partial king posts exposed to the inside.

Historically, regardless of wood species, a tenon is 30mm wide and 70mm deep. Having worked on a frame dating from the 18th century I can attest that this standard long predates the existance of the chain mortiser. Which does suggest that the bar sizes common over here are a consequence of the practice and not the other way around.

Makita make a cross-grain mortiser (KC100) which is superb except for a guide which has a habit of slipping. The with-the-grain model is rarely sold here. I've only met one carpenter who's ever used one and he'd never touch it again. It's just not considered fast enough.

Clearly all of this relates to square cut timbers that are true (or true enough to be usable). All of this goes out the window when working with twisted wood and scribing, although even there I suspect habit would lead most to make supports for the timber and mortiser.

I'll try and post more on French carpentry when I get a chance, if there's interest. I do find the juxtaposition of an incredible tradition of drawing "l'art du trait", and the push for fast-cut treated pine frames fascinating... if a little depressing.