The apse of Notre Dame, post fire. Stunning picture

[machoneman]

11. Yes, the mere size in girth let alone length...

precludes using real oak for the ceiling cross beams. Heck, even the wooden cross-walk up there was made of huge oak slabs cut lengthwise.

I've always marveled at the many USA based Mountain and West Coast resorts/eateries that were either built in the 1800's or had later re-purposed old and giant pieces of wood into ceilings and the like. All show exposed, soaring and magnificent rafters and cross-pieces. These trees (extremely large) though no longer exist IMO in Canada or the US.

The French will need to consider using steel, aluminum or maybe even some kind of carbon fiber for the new roof supports. I wonder too if they will use lead again for the roof 'shingles' not only due to modern environmental concerns (leeching of lead into ground water) but also the estimated 210 metric ton weight, as reported. Modern fireproof materials, far lighter and easier to obtain, could replace lead. Likewise the cross-walk, also hidden from view, could be re-made out of aluminum to lighten the load on the side walls, already weakened 80 years into the original construction, which lead to the brilliant use of the flying buttresses to solidify the walls.

Btw, I'll add that the carbon fiber (CF) idea isn't wild at all. The French Airbus conglomerate slready makes huge CF wings for the latest Airbus jet passenger planes quite closeby. That and another firm that makes equally huge blades for wind powered windmills.