In Nantes, the new wooden “Café de la Branche” faces the Grand Eléphant

Les Machines de l'île are celebrating their 10th anniversary. This is a great opportunity to inaugurate a new "Café de la Branche" dedicated to food and beverage, and to respond to the site's growing traffic. Opening to the public on June 16, this architectural project has invited LCA for this timber construction challenge.


THE MACHINES OF THE ISLAND: AN EMBLEMATIC AND CONSTRAINED SITE

The new Café de la Branche, a great tourist attraction
To mark the 10th anniversary of the Machines de l'île, and to accommodate the increased visitor numbers, a new "Café de la Branche," a restaurant and bar area, has been created on the forecourt of the Machines de l'île, leaving the original space exclusively dedicated to the bookstore and boutique. With a capacity of approximately 100 people, it boasts a large, raised, south-facing outdoor terrace for a glimpse of the Grand Eléphant. Located on an iconic Nantes square, the Machines de l'île site, this new building benefits from a beautiful exposure for visitors, both local and tourist.

A reversible building on a constrained site
Due to the influx of pedestrians on the forecourt, the passage of the Grand Elephant and the heavy traffic on the adjoining road, the construction footprint is limited to 224m² of floor space. The client and project managers have decided to preserve the "reversibility" of the site: the structure is "placed" on the existing concrete slab, in anticipation of possible destruction. The constrained site requires the project manager to make the technical equipment invisible: above-ground grease trap, hood extractor, primary ventilation, etc. The technical space and the patio group together and optimize the location of this equipment.
A 5th category ERP, with a single ground floor, built in accordance with RT 2012, the new "Café de la Branche" responds to the characteristics of the site and the positioning imposed by Voyage à Nantes and Machines de l'île, project owners, and SAMOA*. The work takes the form of a long, slender building, visible on its five sides, with a glimpse of the roof from the "Prototype Branch". This project, located directly above the main rainwater pipe while maintaining access to the inspection chamber, is similar to an impluvium** allowing all the roofs to return the water to the central part, towards the technical patio. In the continuity of the patio, a glass roof illuminates the U-shaped bar.

* Local public development company responsible for project management of urban development on the Ile de Nantes
** Rainwater collection and storage system

CLT IN INTERIOR FACETS: A CHALLENGE LAUNCHED TO LCA
LCA - Les Charpentiers de l'Atlantique -, with its expertise in timber construction with workshop prefabrication, was selected to contribute to the completion of this project. Four LCA employees - a draftsman, project manager, and manufacturing agents - were involved early in the project to work on the technical and structural study and carry out the prefabrication of the timber and CLT elements. For four weeks, a team of two carpenters and a crane operator oversaw the construction site assembly.

The CLT challenge on an emblematic Nantes site
Located on the Machines de l'île tourist site, this project, designed by Christophe Theilmann Architect and Fanny Robin Architect, takes on the technical challenge of using CLT*, or glued laminated timber, in interior facets. “CLT is a structural material that immediately gives a “tone” to the space created and sheltered: sustainable and ecological, insulated and soundproofed.”, explains Christophe Theilmann, architect.

Wood, a key material in construction
"The choice of this "real" material, wood, gives character to the building: from the sloping roofs to the interior soffits continuing to the exterior.", describes the architect Fanny Robin.
On this project, the LCA team ensured the implementation of PEFC-certified timber elements. CLT* roof panels, "visible habitat quality", laminated and fireproofed, form the insulation and waterproofing support for the entire building. Left in an exposed finish, the spruce panels were carefully installed to avoid dirt or damage caused by the construction site. The main structure, made of class 2 spruce, is based on 160x225mm glued-laminated timber posts, and, on the periphery of the building on the exterior facades and on the periphery of the patio and glass roof, glued-laminated beams. Timber-framed walls, made of class 2 spruce, clad the main facades: storage and preparation area, patio and restaurant. Timber cladding is attached as a rain screen to the timber frames. A peripheral canopy provides an aesthetic finish to the wooden structure: exterior posts and brackets, made of de-saped Douglas fir**, form the roof support.

* Custom-made structural panels made of solid wood slats crossed perpendicularly
** De-sapwood: remove the sapwood from a log or a piece of wood


Construction site information
- Geographic location: Esplanade in front of the Machines de l'Ile gallery – Ile de Nantes
- Type of site: construction of a building dedicated to catering and the bar
- Surface area: 224 m2
- Project management: The Journey to Nantes - The Machines of the Island
- Project management: Christophe Theilmann Architect and Fanny Robin Architect
- Technical studies office: Yves-Marie Ligot (78)
- Timber construction company: LCA – The Atlantic Carpenters
- Total cost of the project: €630 excluding VAT
- Amount of the LCA project: €126 excluding VAT
- Duration of the project: 6 months
- LCA construction time: 4 weeks
- Delivery of the site: June 13, 2017
- Open to the public June 16, 2017