Old ways of working still have their place

Mr Minne, who is based near Dieppe in Seine-Maritime, is a former archaeologist who retrained as a ouvrier professionnel en restauration and mason to work with building materials such as clay (what is called adobe in Spanish countries), chaux lime mortar and bauge, pisé and torchis, or cob.

“They are more ecological compared to working with cement and concrete and we have many, many very old buildings in Normandy where these are exactly the techniques needed to keep them ready to last hundreds of years more.

“Below our topsoil here there is clay and this is sterile, pretty solid and ideal for use in building... that is why it is used so much here and elsewhere.

“I like to use terre crue [unbaked clay] and it has no vegetable matter in it, unlike normal soil. The fact it has no humus means there are no seeds or other things to weaken it.

“It is much in use around here and in the north of France – and although I only started my business a year ago there is a lot of work as it is common.

“What encouraged me to start was I took a year out with my partner and we got involved in ‘woofing’ where we worked on environmental projects and we found these traditional materials such as cob were still being used and had stood the test of time.

“Cob building is used in many places, especially in hot countries, and we worked on a new-build cob building.

“In France, it is called bauge and is a mixture of clay, sand and straw with water and often made in frames to build thick solid walls.

“Torchis is a different method [like cob] and it is used as infilling between timber frames, where la bauge is built up on a stone base because the material is affected by humidity. We say in French, and they do in English as well, that it needs both bonnes bottes et un bon chapeau which is a solid and waterproof foundation and a good roof over the top.

“For the outside of many very old buildings we see that there are serious problems because people have used cement to do repairs or to redo the pointing between stones.

“It is completely the wrong material and they must use a lime mortar, called chaux, that is capable of moving with the building and allows humidity to escape. Cement resists humidity much better than solid stone and can even mean the rock cracking.”

Mr Minne has taken part in several workshops to show people how to use some of these techniques and says that in summer the traditional thick walls make a big difference.

“They have a great thermal inertia and that means they are slow to heat up in summer and slow to cool down in winter – so the inside of a bauge building can be cool in summer and need little heating in winter, making them very economical.

“At present this is not recognised in construction regulations and especially not in the réglementation thermique which governs buildings’ insulation although it is under test and could well be included in future versions to give the traditional industry a boost.

“There are different techniques in use all over the country and you can find a traditional artisan or more information through the Maisons Paysannes de France association which protects our historical rural buildings and has a list of artisans who are skilled in local techniques.”

Since setting up his business Six Pieds Sur Terre he has been involved in projects as varied as restoring a wooden lintel and collapsing wall over a window and building a new clay roof for a communal oven.

There is a lot of interest in the techniques and a group in Beauvais, Les Ateliers de la Bergerette, offers classes in using lime mortar and ecological renovation.