Notre Dame

[Mark Gibney]

I read an article about a possible approach to rebuilding Notre Dame, using 13th century techniques.
The article discussed the building of a chateau, Guédelon Castle, a few hundred kilometers south of Paris using 13th century tools and methods (and clothing, from the few photos).

The people involved in building the castle insist their approach is the best way to rebuild Notre Dame.

“The roof frame was extremely sophisticated, using techniques that were advanced for the 12th and 13th centuries,” says Frédéric Épaud, a medieval wood specialist. “After the fire, there were a lot of people saying it would take thousands of trees, and we didn’t have enough of the right ones, and the wood would have to be dried for years, and nobody even knew anything about how to produce beams like they did in the Middle Ages. They said it was impossible."

All well and good. I was hoping the article would go into specifics about the process and how and why it might be better than a modern approach, but unfortunately what we get is a few declarations of the mysticism of respecting the tree - "Stéphane Boudy, one of a small team of carpenters at the medieval site,
explains how hand-hewing each beam – a single piece from a single tree – respects the “heart” of the green wood that gives it its strength and resistance."

Maryline Martin is co-founder of the Guédelon project, and says "some people wrote us off as a theme park. Now, after 25 years, we are the only ones who can understand and are able to do what has to be done, and they discover we have not sold our soul to the devil."

These quotes show that these artisans are dedicated to their craft, if a little defensive about how outsiders might regard them. For myself, I hope there will be future articles that go into greater depth than this one, explaining the pro and cons of approaches to rebuilding the cathedral.
To put my cards out there, I cannot see how hewing beams from a single trunk would be better than building glue-lams or such. Happy to be shown otherwise!

[Bill Dufour]

I think the 1836 replacement roof structure at Chartres looks very impressive from inside. Today they would use steel not cast iron. I do not trust wood glue to hold in attic heat and cold for 1,500 years. So ther emay be a reason to use solid wood. I would use a bandsaw or chainsaw for shaping the timbers not an adz.
Bill D

https://www.abelard.org/france/cathedral_buttressing_chartres.php

[Kevin Jenness]

I don't know that from an engineering perspective traditional timber framing techniques are "better" than other approaches using gluelams or metal framing but there is certainly a strong argument to be made for rebuilding the cathedral roof using the traditional techniques originally used, and that is what has been decided thanks in large part to the advocacy of Charpentiers sans Frontieres. https://www.facebook.com/Charpentierssansfrontieres/ Fortunately the roof structure was thoroughly surveyed and documented not that long ago and there are some truss elements that survived the fire which will guide the specific joinery details used in the reconstruction.

I have not seen the article to which you refer, can you provide a link? I had to laugh at the widespread skepticism after the Notre Dame fire that there survived the knowledge and skill in the various trades to remake the lost elements. Europe is far better off in that respect than the US due to their large inventory of ancient buildings and commitment to keeping them in use. There are more than a few timber framers in this country who are adept in traditional techniques, and some of them will be employed on the Notre Dame roof project. https://architecture.catholic.edu/about-us/notre-dame-truss/index.html

My understanding is that the timbers will be sawn and then hand-hewn to reproduce the traditional surface.

[Frederick Skelly]

To put my cards out there, I cannot see how hewing beams from a single trunk would be better than building glue-lams or such. Happy to be shown otherwise!

I don't know that it's a question of which would be better. Both ways probably work and will make a strong structure. I think the open question is which way is more "appropriate" - and there's a lot of subjectivity in that. Should they try to restore as closely as possible to keep the roof structure consistent with the rest? If they build back with "some" modern materials/techniques, does it devalue or detract from the cathedral's heritage or cultural value? What message do we send to the future by making either choice?

Personally, I'd say using "too much" modern technique probably does diminish it to some extent. But you get into this same argument when talking restoration of anything - furniture, cars, houses, etc. I also know that sometimes, you have no choice - can't recreate the original part, etc.

I'd love to hear the views of Tom King, or other professionals who do restoration. They'll have first hand experience.

[Tom M King]

They had already decided, and have been working on for several years now, to replace it as closely as possible like it was. There are very detailed drawings of how everything was built that already existed.

The biggest problem is politicians, that know nothing about building anything probably, have set a deadline that won't even allow long enough for the big timbers to dry much. People who don't know anything about building think that the most important thing about building anything is to do it fast, and not just for thousand year old cathedrals.

[Tom M King]

Do a search on youtube for Notre Dame restoration, and you will find good updates, such as:

https://www.youtube.com/watch?v=Hw2NPzHhVfQ

[Curt Harms]

I think the 1836 replacement roof structure at Chartres looks very impressive from inside. Today they would use steel not cast iron. I do not trust wood glue to hold in attic heat and cold for 1,500 years. So ther emay be a reason to use solid wood. I would use a bandsaw or chainsaw for shaping the timbers not an adz.
Bill D

https://www.abelard.org/france/cathedral_buttressing_chartres.php

That's something I've wondered about and not just in 1000 year old cathedrals. I think I mostly get the advantages of glulams and other built-up components held together with adhesives. I do wonder if those structures are going to be life limited.

[brent stanley]

That's something I've wondered about and not just in 1000 year old cathedrals. I think I mostly get the advantages of glulams and other built-up components held together with adhesives. I do wonder if those structures are going to be life limited.

The only thing we know for sure is solid wood structures can indeed live for centuries, because there are so many examples surviving. We have differences in quality of wood sometimes, and we have some understanding of what that might mean to longevity, but it still may be the best choice. Modern adhesives are certainly a bit of an unknown

I wonder how dry the original timbers would have been when worked? It's fairly accepted for historical NA timber work that drying time before joinery/erecting was only determined by how quickly they worked, and only rarely by deliberate planning for drying/curing.

[Dave Sabo]

They had already decided, and have been working on for several years now, to replace it as closely as possible like it was. There are very detailed drawings of how everything was built that already existed.

The biggest problem is politicians, that know nothing about building anything probably, have set a deadline that won't even allow long enough for the big timbers to dry much. People who don't know anything about building think that the most important thing about building anything is to do it fast, and not just for thousand year old cathedrals.


When public money is to be used, the pols get a say. End of story.

If you want the artists to run the show - send em a blank check from your bank and be prepared to never see the project finished in your lifetime.

[Kevin Jenness]

I believe this is the article to which Mark was referring https://www.theguardian.com/world/2022/aug/20/notre-dame-cathedral-fire-rebuild-medieval-carpenters-guledon.

The people quoted seem a bit full of themselves when they say only people trained there have the skill of "cutting, squaring and hewing wood by hand" and "There’s no heart in sawmill wood". Still, they deserve respect for maintaining the skills although they are scarcely the exclusive inheritors of timber framing traditions. Whatever their opinions, the contract has been awarded, the work will be done with green timber using traditional joinery and a mix of traditional and contemporary tools and the frame is scheduled to be erected next summer.

[Frank Pratt]

I believe this is the article to which Mark was referring https://www.theguardian.com/world/2022/aug/20/notre-dame-cathedral-fire-rebuild-medieval-carpenters-guledon.

The people quoted seem a bit full of themselves when they say only people trained there have the skill of "cutting, squaring and hewing wood by hand" and "There’s no heart in sawmill wood".

I agree. They aren't doing themselves any favors when they get carried away with the hyperbole like that.

[Mark Gibney]

Yes that's the article.
Sorry I didn't get back on here to post that for you, I had a deadline that kept me off the computer.

[Donald G. Burns]

A nice video on the trees being used in the Notre Dame restoration: https://www.youtube.com/watch?v=apQRPEn-SbI

[Mike Rambour]

Notre Dame is 859 years old, she was 857 when the fire happened. We have a hard time building anything that lasts 100 years in this day and age. I would never trust a glulam to last that long. She was built with mostly green wood back in the day and that is what they are going to do again. The timbers are dried a little and then hand-hewn to work with the wood and its natural movement twist. There are quite a few videos about it online. When the fire first happened, there was talk of going modern construction since hardly anyone ever sees the 'forrest" as the roof was called. I am lucky that I actually did see it back in the 80's. Since hardly no one sees it, it could be steel beams and no one would be the wiser but they are going back to original since it is proven technology to last a very long time. I don't care what they rebuild it with as long as it looks right from the outside and lasts a 1,000 years this time, that pretty much implies no new technology or steel beams and solid wood beams since we can't build anything that lasts anymore.

My first visit to Guédelon Castle was in 2002 and again just before Covid, the work and most important the speed of the progress is nothing short of amazing.

On a personal note, I do keep up with this stuff. From age 2 to 9 (ok first few years don't matter), I lived only a few blocks away before my mother moved us to the States. I have a firefighter cousin who actually was fighting the fire and I have 2 stone mason friends that are doing work on the church

[Jim Becker]

Nobody should underestimate the building and restoration prowess of the folks in that geography...even the new "modern" construction in Europe is built to last centuries. Despite all the "advantages" we have these days in understanding materials, stresses, etc., those early engineers had a remarkable knowledge, so personally, I see nothing bad about doing the restoration using traditional material and methods as much as possible. But related to that, any impatience from the stakeholders really has to be tempered by the reality of "doing it right" the first time and the operative word absolutely is time.

[Curt Harms]

The original builders back in the middle ages didn't have the 'advantage' of modern materials testing and analysis. I'm sure things back then were overbuilt, maybe by a lot. I wonder if that's why things built back them last longer than modern construction.

[Tom M King]

Over built with a long lasting roof over it.

[Robert LaPlaca]

Tom wasn’t the metal roof sheet lead. IIRC it’s doubtful the metal roof would be constructed of the same material.

[Warren Lake]

they didnt need the modern testing they had history testing.

Cabinetmaking knows a mortise and tennon is a good joint as it has over 1000 years of proving itself.

Modern dumbed it down to cope and stick by people who could make money off selling you cutter heads telling you it will save time.

[Tom M King]

Yes, lead roof. I don't know what their rules are about lead over there.

[Andrew Hughes]

They also have divine providence. Keep technology and scientists out of it.
Trust the Craftsman Let them do their work.

[Bill Dufour]

The fire melted the lead roof and it poured out the downspouts and also inside the building. used to be common to take off the roof and melt it into bullets when needed. Roll back into roofing sheets after the war.
Bill D

[Andrew Hughes]

Lead coated copper is what I’ve seen and used for historical restorations. Roof jacks get pure lead or areas that need to bend crickets and valleys all heavy 16 ounce copper coated with lead.
I like slate roofs the best with proper details. It will last forever

[Tom Bender]

The new roof will be lead or lead coated? Really? When I think about how obsessed we got over asbestos my money is on the lead being removed in a matter of decades due to the same sort of over reaction.

[Curt Harms]

Yes, lead roof. I don't know what their rules are about lead over there.

I don't know either. The application isn't plumbing or paint where the lead is likely to be ingested one way or another.

[Frank Pratt]

Tom wasn’t the metal roof sheet lead. IIRC it’s doubtful the metal roof would be constructed of the same material.
The documentary said the roof will be lead and I've read a couple of the papers that indicated the same.

[Steve Rozmiarek]

Can you imagine trying to get that project by a code inspector here? I'd take longer for them to figure out who to get to sign off than the actual work.

[Donald G. Burns]

What a lot of people don't know is that the Washington DC national cathedral was built using only the old masonry skills - no iron

[Frederick Skelly]

What a lot of people don't know is that the Washington DC national cathedral was built using only the old masonry skills - no iron

That was interesting. Thanks for flagging it. Put on your "Wikipedia filter" (they arent always 100% accurate), but here's what their article says: "Most of the building is constructed using a buff-colored Indiana limestone over a traditional masonry core. Structural, load-bearing steel is limited to the roof's trusses (traditionally built of timber); concrete is used significantly in the support structures for bells of the central tower, and the floors in the west towers."

[Bill Dufour]

It was not unknown for half built cathedrals to collapse. Especially if the soil was not good for the foundation. Same thing for the first pyramid. It was too steep so they changed the slope when they were half way done. The rocks had started to crack from the load.
The Meidum pyramid central core is still intact. All the outer stone to form a pyramid from step pyramid collapsed into the piles of rock leaning up to the base. That pyramid should be on a flat a plain.
Bill D

https://en.wikipedia.org/wiki/Meidum#Pyramid

[andrew whicker]

Everything requires maintenance to last 1000's of years. We aren't talking about a building that stood for that long with zero maintenance. Hell, the fire started due to maintenance gone wrong.

The Notre Dame restoration will be reviewed by engineers and have stamped drawings. If a truss needs to be replaced, repaired, etc later on there will be money in the coffers to make it happen. I'm sure the building will be regularly inspected.