Slate or tile? In Anjou, a line divides the roofs

High basement

If the slate covers the majority of Breton and Angevin roofs, it is above all a question of geology. The basement of the Armorican massif is rich in slate shale. It stretches from Cotentin to Vendée, and pushes to Trélazé, to the west.

Beyond the Paris Basin, much richer in clay, the raw material of the tiles. Unsurprisingly, the map of France of the roofs in tiles and slates marries, almost per kilometer, this invisible border because underground. “To cover the roofs, we took the material we had on hand,” summarizes Sébastien Ritouet, manager of a cover company met in Huillé-Lézigné (Maine-et-Loire).

This border between the West and the rest of France is also explained by cost reasons. The Nantes in Brest canal, built in the 19th century, rendered the transport of the affordable Breton slate for the bordering municipalities and for those of the Loire, linked to this canal. As the land was signed, the cost of transport increased, dissuading the inhabitants to use it. It left traces.

The more I move away from the Loire, to the north and in the south, the more the slate becomes scarce on the roofs. Vincent Gouriou, the photographer, and I note, amused, that municipalities, to a median point of distance, include an exact proportion of slate and tile roofs, offering a pleasant checkerboard. This is for example the case in Mauléon (Deux-Sèvres).

But the local rock and the cost of transport do not explain everything. For a long time, in certain places, including Anjou, the tuileries rubbed shoulders with the slates and offered similar prices. Even today, their prices are close. The final choice is often due to local know-how. “My guys know how to do the tile less, it takes them more time. So we invoice it more expensive than the slate, ”specifies Mathias Coutant, manager of a cover company in this village and president of the School of Coverage of Angers. The roofers of Anjou are most often trained in this establishment. However, he has developed an excellence of excellence in the slate. This is due to its history: it was founded in 1929 by the Ardoisières de Trélazé.

Of the importance of prestige

The concept of prestige should also not be overlooked in the choice of material. We find slate on almost all the sumptuous buildings in France, the Palace of Versailles in the town halls of the Midi, even though its transport was expensive.

But it was inconceivable to deprive yourself of what was considered the noblest of the cover materials. “In the last centuries, the castles were generally covered with slates, the tile buildings, and the chaume dependencies,” explains Jean-Yves Hunot, archaeologist of the frames.

I wonder: why was the slate seen as more prestigious? Mystery. Because it is not in itself superior to the tile, I learned with stupor during our meetings. On the contrary.

“The tile often protects better against heat and cold,” reveals Sébastien Ritouet. Some tiles also adapt very well to steep roofs, unlike another received idea. Tiles and slates have the same lifespan, one hundred and fifty years, or even more if the attic is well ventilated and if the hooks are durable. Formerly made of steel, therefore rust subjects, they are now stainless steel.

In truth, roofers teach me, the preference for the slate comes from its malleability. It is more easily size than the tile – in diamond, in heart, in scales … – and is thus more suitable for complex roofs, turrets, lantern, popular with notables.

The more I dig the subject, the more I understand that this border of Tiles-Ardoises is the responsibility of the intangible. North of Anjou, the village of Rairies (Maine-et-Loire) developed a terracotta and tile industry in the middle of the slate. Sometimes local traditions decide on those of neighbors. Or craftsmen export their know-how to distant sites. “I saw flat tiles on Mont-Saint-Michel”, notes François Jeanneau, former architect of historic monuments, crossed on a site. We also detect nuances in the rest of the country. Because slates have been dug in the Pyrenees, the Ardennes and Limousin.

Competitiveness deficit

If the French slate mines have disappeared, it is mainly because they did not have the means to invest to remain competitive. “In Brittany, almost all were family properties, often artisanal,” says Lena Gourmelen. The Ardoiser de Trélazé, with the more substantial means, could not compete either with the open careers of Galicia, in Spain, where almost all the slate sold in France today. “To extract the slate of Trélazé, it was necessary, at the bottom of the mine, a machinist, a recipient, an enclosure, a delayer … Egrene Alain Roger. Twenty men in all. In Spain, five are enough: sawyers, a machine driver, a truck driver. »»

The roofers inform me that the slate of China appeared in France ten years ago. Many refuse to buy it. “I find it ridiculous to bring it from the other end of the planet, says Sébastien Ritouet. Galicia is still going. It’s Europe. »»

Two conglomerates, one Canadian (Cupa Pizarras) and the other German (Rathscheck), are gradually bought the last Spanish slates. To the chagrin of Mathias Coutant: “Family societies were more looking at quality. »»

Roofers go so far as to suspect an agreement between the two groups. How to explain, if not, that the price of the slate has been multiplied by two from the covid? “It becomes a luxury product,” deplores Sébastien Ritouet.

As for the tile market, it is dominated by the Austrian Wienerberger. He bought most of the French tuileries, which are rarefly. I thus discover that the slate and the tile are not impermeable to the bad weather of financial capitalism.

Another factor explains the fall of Trélazé: the quality of its slate deteriorated. “We arrived at the end of the deposit,” admits Alain Roger. Régis Defais, a roofer of the company Coveries of Loire, in the thirty-six years of experience, confirms it to us on the roof of the college-Lycée Mongazon d’Angers, where he replaced the slate of this building of 1836. “That of Trélazé was rolling too much”, he recalls. It contained more and more pyrite, a mineral who accelerates rust. Fascinated, we watch him fix the slate squares with an amazing dexterity. And with a tool that has not been looking for, unchanged for centuries: the hammer-enclume.

Delicious noise

From the golden age of Trélazé, he remains, in addition to the slate on the roofs, the chivalments, these towers which descended the minors. They bristle the countryside and the old quarries transformed into parks. Also remain, to my surprise … Trélazé slates. You can buy it at the slate museum.

The minors have kept stocks that Jean-Christophe Boisteault, the latest slaughter of France, employee by the museum, transformed into board games, plates or pendulums.

We see him grab a long splitting chisel, the cobra, and slice the slate with a bright blow. She emits a delicious crystalline noise. “She sang, it’s good,” he appreciates. This means that she accepts what I ask her to do. His gestures hypnotize us. Unfortunately, his know-how is threatened. He will retire in five years and it is not planned that he will form an apprentice.

Other cover materials are gradually appearing: aluminum, steel, synthetic … But the municipalities, via the local urban plan (PLU), can prohibit any change of materials on roofs, in particular around a historic monument. The PLU is the last reason for the persistence of this border between tiles and slates. And also his last rampart.

The roofer Mathias Coutant defends this tradition: “Standardized products make our achievements insipid. However, we know how to do things with taste, thanks to the sensitivity of our hands, our understanding of materials, rain, light, wind, the passage of birds. Because a roof vibrates. It’s poetry. »»