It's been two years today since Notre Dame burned. How can a stone building burn? you ask. Well, limestone (such as the church is made out of) will burn when hot enough (it's burned as one of the ingredients in cement), but the real problem at Notre Dame was the roof beams. The roof itself was lead (and the fire spewed the whole area around with toxic lead dust), but the beams were 900 year old oaks. After 900 years, as you can imagine, the wood had gotten very dry, and once it started burning it was very hard to put out.
After two years, the building itself is stabilized, the walls aren't going anywhere, and most of the interior decoration, which came through surprisingly well, was rescued. The biggest damage, besides the roof itself, was to the stone vaulting (ceiling) at the point where the transept (the crossing) crossed the nave (the long central aisle of the church). In the nineteenth century a spire was erected there, and when it crashed down it took out the vaulting.
Right now efforts are underway to repair the roof, which they are planning to put back more or less as it was. They are even planning to replace the spire, but I could have told them that was a bad idea (they didn't ask me). The challenge is getting enough oaks. They actually have an excellent idea of how the beams worked, because modern timber framers have closely studied all old wood-framed structures, as they sought to revive what had almost become a lost art, and Notre Dame was one of the best examples.
Oak trees, as you doubtless know, are fairly slow growing but produce good, strong wood, and they were appreciated for beams throughout the Middle Ages. The problem was giving the trees long enough to grow. Burning wood was the principal way to keep warm, and oak makes a nice, hot fire. Everyone building something, from a church to a castle to a little house, wanted nice oak beams. It was considered miraculous in the early twelfth century, a generation before Notre Dame was built, that Abbot Suger was able to find enough oaks big enough for his new church's beams. And then you have the problem that when people want to plant new fields, forests are the enemy, to be chopped down.
Sad but true: two centuries ago, when Ohio was being cleared for agriculture, they chopped down thousands of oaks and burned them in bonfires that could be seen for miles.
In England in the early modern period, some forward-looking people realized that some of their new halls and churches might need new beams at some points and created oak groves especially for the purpose. When beetles got into the beams two or three centuries later, the oaks were ready.
Medieval people recognized the value of woodlands around the same time they were being cut down, just as happened in the US centuries later. Oak woods had been important, even sacred, going back to the Gauls, before the Romans arrived. It is even believed that the word druid is related to the Celtic word der, meaning an oak grove.
Medieval peasants wanted oak woods because pigs were fattened on the fallen acorns; indeed, woods might be described by how many pigs they would support. Ships were built from oak planks; the Vikings had fairly untouched Scandinavian forests to draw on for their ships. Oak galls provided one of the ingredients for medieval ink. Oak bark was used in tanning leather.
Carpenters drew distinctions between different trees, depending on whether they grew on a hill or a flat area, among other trees or by themselves, on stony or sandy soil, even whether they were on a north or south facing slope. These things influenced the grain and the strength of the wood.
Europe's modern woodlands are much more thoroughly managed than are American woods. Those rebuilding Notre Dame are starting to assemble enough big oaks. Some of the managed woods routinely cut down the oldest trees to allow younger trees to grow up. Some of these culled oaks are destined for Notre Dame. The challenge is going to be finding enough of them, especially since the French prefer French oaks, or at least European oaks, not Chinese or North American ones.
© C. Dale Brittain 2021
For more on architecture and other aspects of life in the Middle Ages, see my ebook, Positively Medieval, available from Amazon and other major ebook platforms. Also available in paperback!