French eco-designer presses for return of earth bricks

So he built one himself.

Mr Gay, who started an eco-construction company after getting fed-up with his job in the aeronautics industry, had heard about compressed earth bricks from a neighbour.

“It is an old technique, which fits in well with eco-building methods and people trying to leave only a small carbon footprint,” he said.

The bricks are made using a mix of ordinary earth which has been sieved, a bit of lime or cement, and water, then having the mixture compressed hard.

In Mr Gay’s machine, the pressure comes from an electrically-driven hydraulic system, which pushes from the bottom and the top. The bricks “cure” for 21 days if lime is used, or 27 days with cement, before being moved to dry in open-air hangers for a month.

The result is a brick a bit lighter than the colour of the earth it was made of, with very high insulating qualities for both sound and heat.

Earth from the building site can be used to make the bricks, either on site or at the factory.

“People think they can make enough bricks from the earth they dig out for the foundations and to lay the floor, but you usually need more,” said Mr Gay.

“But there is almost always someone not far away who has been digging and has some earth they are happy to give.” Each brick costs up to two and a half times the price of traditional bricks, but for most walls, the overall increase in material costs is between 10 and 15%.

This is because less lime mortar is used, and because the bricks do not need to be covered by insulating materials.

“I am sure that as word spreads and I start producing more, the price will fall,” said Mr Gay, who was awarded the éco-défi label for his product.

This certification is run by regional Chambre des Métiers et de l’Artisanat to reward ecologic efforts in areas such as waste management, water use, packaging, transport and sustainable materials.

Compressed earth brick walls are almost always rendered if they are used as exterior walls, using lime and sand rendering, so that they can breathe.

The problem faced by Mr Gay and others pushing to popularise compressed earth bricks is that they do not meet French building norms, established in 1945.

“No one imagined that compressed earth bricks would make a comeback, so nothing was written for them,” said Mr Gay. This means you can use them if you are building your own home but not if you have a professional do it for you.

Exemptions are provided on a case-by-case basis, and are expensive to get.

Each certifying body insists on tests being carried out in independent laboratories. A public library in Toulouse built with Mr Gay’s bricks spent €60,000 getting the exemption.

“You cannot expect someone having a builder to build their home to pay this,” he said.

Eco building groups are lobbying to get the restriction lifted but counter-lobbying from brick industrialists means it could take another five years for the norms to be changed.