Pascal JACOB

Chairman of Elysées Mogador and of Strater

Roof and timber structure engineering and expertise

Vice Chairman of the French Water & Forests Association 

pjacob@pascaljacob.com – www.pascaljacob.fr

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Mr Emmanuel MACRON

President of the Republic of France

 

Palais de l’Elysée

55, Rue du Faubourg Saint-Honoré

75008 PARIS

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Paris, 19 April 2019

Rebuilding the roof of Notre Dame Cathedral in Paris

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Dear President Macron,

 

Not rebuilding a faithful copy of the roof of Notre Dame would dispossess a nation on one of its highly-cherished symbols and probably one of the finest examples of a timber roof structure in the world. 

 

Right now, when we are struggling to deal with the disastrous effects of greenhouse gas emissions, the use of anything other than wood would send the wrong global message to the ecological movement, led by our country since the COP 21, which took place in France and where the first universal climate change agreement was ratified by all 196 parties. 

 

Without comparing materials, the use of wood for the load bearing elements of the future structure offers lots of advantages over concrete or metal, despite an emergency response being to give priority to these materials, as has been the case in the past for the rebuilding of some of our cathedrals and other monumental works.  Let me remind you that if the roof structure had been made of concrete or metal, it would never have lasted nine centuries and, in the light of the intensity of this fire, Notre Dame would probably not still be standing. Both concrete and steel soon become unstable at very high temperatures. The structure would have collapsed, destroying the vault completely, weakening the whole structure and this would have led to the cathedral’s demise.  Everyone saw that the remains of the consumed timber structure stayed above the vault and did not damage it, except where the spire collapsed. This was confirmed by the aerial images of the fire. Furthermore, whichever construction system we choose, we cannot eliminate the risk of a fire. 

 

The sole difficulty of a timber reconstruction does not lie in the inability to find oak timber in sufficient quantity or quality – this is not being debated (1) – but in the ability of sawmills to dry out the lumber if we select solid timber of similar squaring to the old roof structure. It is worth noting that due to the lifting difficulties of the time, this structure was made of relatively short sections of timber.

 

What is more, several years will pass before the work is done and this would allow the selected timber to dry out progressively and decrease the need for artificial drying. There are also new technical solutions that allow the use of materials such as reconstituted solid wood and, in particular, glued laminated oak timber. This technology gets round the problem of drying, since reconstituted materials are made of boards that are much easier to stabilize.

 

Furthermore, Notre Dame Cathedral was designed and built using a method associating wood and stone. This initial design made allowances for the specific features of wood, such as lightness and elasticity. If we rebuild a faithful copy of this structure, the marriage will not need to be called into question and will help guarantee the deadline you have set of five years. On the contrary, if other constructive systems are chosen, this would require elaborate studies and would delay the reconstruction significantly.

 

Last of all, our country has all the technical skills required to rebuild the cathedral. Firstly, we have a large number of engineers in France specializing in timber structure capable of modelling and studying such a structure. We also have a great many French contractors with the required qualifications, capable of rebuilding Notre Dame. Lastly, in choosing to rebuild a faithful copy of the Notre Dame Cathedral’s roof structure, this would send out a wonderful message of hope to young people wishing to follow a career in crafts, trades and arts using a beautiful, noble, ecological material such as wood.

 

I would be happy to discuss this with you at any time.

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I have the honour to remain, Mr President, most respectfully yours,

 

 

 

 

 

 

 

 

 

 

 

Pascal JACOB

 

 

 

 (1) See the excellent article by Mr Jean-Marie Ballu (www.afef.fr), Chairman of the French Water & Forests Association, recognized as of public interest since 1937, approved by its board on 17 April 2019.