#vmzinccolumn

TO THE POINT: VMZINC’s Column

Extreme zinc: 115 years at the summit!

Zinc is resilient over time. And despite the unpredictability of weather on mountain peaks! The Fourches Camp is proof of this: a French army mountain barracks, located at an altitude of 2,291 metres in the Mercantour mountain range in the Alpes de Haute Provence region. The barracks was built in 1896, and its magnificent roofs were renovated in 2016! We have a look at why and how.

Impregnable bastion

Regularly used as a campsite from as early as 1890 by the famous Alpine hunters, commonly referred to as the “blue devils”, this bastion was an element of the military system implemented by France following its defeat in 1871, to protect the border with Italy.

The barracks is made up of twenty-six buildings, built using local stone. Twenty of these are practically identical, and look like chalets with double-sloped roofs. During the 20th century, a command post with an officers’ mess and a first-floor optic telegraphy post were added.

 These chalets were mainly used as accommodation and could house one battalion, i.e. four companies for a total of 150 men living in quasi self-sufficiency.

The Fourches Camp was permanently occupied, except during the winter, when a reduced number of men were in charge of guarding it. It is said that circulation between the chalets took place under the snow (which is abundant at this altitude) in galleries made from planks of wood.

Memory renovation

A place of memory of the battles of the Alps, in 2014, the Fourches Camp was redeveloped with a view to turning it into a tourist attraction (a major hiking route). The renovation work, led by the Maritime Alps Region General Council, began in June 2016.

Our technician, Jean François Taillard, was called on by SMBR Entreprise and Pierre Verdet during the summer of 2016. His mission: work on the complete renovation of the roofing, in this very particular high altitude mountainous context.

Patented VM system: a work of art!

To Jean-François’s surprise, during his first visit to the site, he was delighted to observe that some buildings had been originally roofed with zinc shingles, and significant sections of the roofing were still covered with these. He was able to remove some elements from a building dating back to 1902, and discovered - thanks to the thickness indicators (gage of 12, i.e. approximately 0.65 mm), still visible on the back of the shingles (see photo) – that these had been manufactured at the Vieille Montagne plant in Viviez-Penchot (the letters V-P are clearly visible) in the south-west of France…over 115 years ago!

So this roofing withstood more than one century of onslaughts from a particularly harsh climate. In particular, extreme cycles of variations in temperature between summer and winter.

Another source of satisfaction, Jean-François was able to do a little technical archaeology by evaluating the fixing system of this roofing, made up of small elements. He also made a fascinating discovery: the original fixing system, using special pre-fabricated clips turned out – after looking through old catalogues – to be a patented Vieille Montagne system, suitable for installation in mountainous regions. Why?  This fixing system made it possible to cleverly avoid build-up of powdery snow at the junction between 4 shingles.

 On our advice, the client agreed to the idea of renovating these roofs in keeping with the original method used and with the same material. And so we were able to once again provide Adeka light grey preweathered zinc shingles (Quartz-Zinc ®), which are also fixed on the upper part using a patented locking key! So, off we go again for another century!

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