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France’s timber lesson

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Latrobe Valley Express, 15 January 2025

On the first anniversary of the Victorian state government’s closure of Gippsland’s native forest industry, France’s rebuilt historic Notre-Dame Cathedral has been completed in all its glory – and French timber was at the heart of this historic project.

The oak hardwood timber used came from trees in French forests between 80-150 years old, with some more than 200-years-old.

The rebuilding of Notre Dame received PEFC certification, the world’s largest forest certification standard, which certified the sustainability of the solid oak used to rebuild the cathedral’s roof structure. Oak is regarded as the queen of the French forest.

PEFC, founded in 1999, is present in 56 countries.

Victoria’s hardwood native forest, and native forests in Tasmania, New South Wales and Queensland, are certified to PEFC standard through Responsible Wood and the Australian Forestry Standard. However, France’s achievement stands in contrast to Victoria, where the state government closed the native forest industry due to a mix of factors – which some believe was little more than political malice and cowardice, environmental hysteria, and intellectual ignorance and naivete.

The government claimed native forest harvesting was unsustainable.

The medieval frames of Notre Dame’s nave and choir, built in the 13th century, and those of the spire designed by French architect Viollet-le-Duc, and both arms of the transept, dating from the 19th century, were destroyed in the fire on April 15, 2019. They were restored identically, using the same techniques and materials as the original, solid oak.

The contracting authority for the restoration project, ‘Rebatir Notre-Dame de Paris’, noted in a statement that by rebuilding Notre-Dame de Paris’ roof structure in wood, part of which – the great roof – is also known as “the forest”, the shared history of the cathedral and French forests would continue to be written for centuries to come.

“Like Notre-Dame de Paris, France’s forests are living symbols of our tangible and intangible cultural heritage, so it’s important to preserve them to ensure their longevity for future generations,” said the authority’s president, Philippe Jost.

The certification from PEFC and the FCBA Institute of Technology (Forêt Cellulose Bois-construction Ameublement) confirms the sustainable origin of the solid oak wood materials used, and the responsible nature of the work carried out by the contracting authority, chief architects of historic monuments and project managers.

The mission of the FCBA, founded in 1952, is to promote technical progress and contribute to improving efficiency and quality assurance in industry.

The institute’s scope covers the entire forestry-wood and furniture sector: forestry, pulp and paper, logging, sawmills, carpentry, joinery, structures, wood-based panels, furniture, packaging and miscellaneous products. The entire French forestry and timber industry mobilised to supply the wood needed to meet the specifications of the project.

Actors from state-owned forests, community forests, forestry cooperatives, forestry experts, private owners and processing companies were all involved in ensuring that each stage of the reconstruction of the frameworks was carried out using a sustainable forest management approach, which is maintaining the balance between the economic, social and environmental dimensions of the forest.

This systemic approach enables the renewal of the forests from which the timber was sourced, thereby maintaining their multifunctionality, while preserving diversity, vitality, productivity, and regeneration capacity.

According to PEFC, sustainably managed forest is a forest where biodiversity, soil health, water courses and wetlands are preserved.

“It is healthy and able to renew itself, whilst providing a range of benefits including timber and timber products, carbon sequestration and opportunities for leisure activities.”

PEFC project certification stipulates that at least 70 per cent of the total volume of wood used is PEFC-certified, ensuring that PEFC’s forest certification requirements, which define and control a set of forest management rules applicable to all forest stakeholders (forest owners, forest managers, forest operators, forestry contractors), have been implemented.

Additionally, the implementation of PEFC chain of custody in project certification certifies that all parties involved in a construction or renovation project, whether certified companies or subcontractors, have applied the control principles defined by PEFC, making it possible to track the flow of certified wood at every stage of the supply chain.

The Notre Dame project involved 35 PEFC-certified sawmills, 175 PEFC-certified forests, and the use of more than 80 per cent PEFC-certified logs.

PEFC’s rules for sustainable forest management and chain of custody enabled PEFC certification for the entire Notre-Dame de Paris timber reconstruction project.

The tree selection process began in early 2021. Chief architects from historic monuments aimed to find the straightest trees possible. This enabled restorers to work on logs measuring 7-20 metres, with diameters ranging from 50-110cm, while still having the strength required to support several hundred tonnes. The trees had to be between 80-150-years-old, with some more than 200-years-old.

The final trees were selected, but they had to be harvested in a way that respected the existing area.

For example, PEFC said the trees cut for Notre Dame had reached maturity and had already seeded the surrounding soil, enabling a new generation of trees to replace those harvested. Most of the selected oak trees came from either state-owned, communal or privately owned PEFC-certified forests.

The first trees were felled on March 5, 2021 and the final oak on February 8, 2023.

Once harvested, the logs, each weighing 10-15 tonnes, were transported to their destination – sawmill, warehouse or processing site.

Sawmilling into structural sections took place between September 2021 and June 2022.

In all, more than 2000 oak trees, the equivalent of 4000 cubic metres of logs, were needed to rebuild the spire and the framework of the choir and nave.

According to PEFC, these 2000 harvested trees made up less than 0.2 per cent of the oak trees harvested annually in France.

FCBA calculations show that France’s oak forests regenerate 1500 cubic metres of wood per hour.

The first phase of the project began with the reconstruction of the spire and two transept arms designed by Viollet-le-Duc, using 19th century techniques.

The second phase of the choir and the nave involved rebuilding the medieval frameworks. This required mastery of traditional, medieval carpentry skills, including squaring – a technique for cutting beams with an axe, which follows the direction of the wood fibres and makes each piece unique.

On July 11, 2023, the first trusses – large, wooden triangular load-bearing beams 14m wide and 12m high and weighing more than seven tonnes and essential for the structure of the building were transported on an 80m-long barge along the Seine River to the foot of the construction site.

They were then lifted by crane high above the cathedral’s vaults to their final positions at the top of the cathedral.

Reconstruction of all the roof structures was completed on March 8, 2024.

More than 100 trusses make up the structure of the great roof – nave, choir and transept. All structural rebuilding work ended on April 8, 2024.

Christine de Neuville, President of PEFC France, said certification recognises the commitment of not only the client, Rebâtir Notre-Dame de Paris, but also of the entire forestry and timber industry to the long-term survival of the French forest.

Mr Jost said certification recognised the strong support of all players in the forestry and timber industry: the ONF, France Bois Forêt and its members, the mayors of forest communities, private owners and their representatives, and sawmillers all over France, who donated trees and processed the timber.

“I extend my warmest thanks to them, as well as to the hewers, squarers and carpenters who have placed their expertise at the service of the cathedral’s rebirth, as part of an exemplary restoration project”, he said.

Official figures show that 3.8 million ha of the 17 million ha of French forest – 22 per cent of the surface area, are oak.

The total volume of standing oak is estimated at 615 million cubic metres, or 1.2 billion trees.

Annual biological oak production is estimated at 12.8 million cubic metres, of which only 6.5 million m3 is harvested – about half of annual production. The oak stock thus increases by more than six million m3 annually.

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