In Morbihan, a carpenter builds cardboard houses

At the heart of his workshop in Morbihan, Nicolas Le Dirach seizes his chainsaw and attacks thick “cardboard breads” as he calls them. Objective ? Cut precisely pieces of this material to insert them into the wooden skeleton of a roof. He was assembled the same morning with John, his collaborator, former employee of an insulation company. Knowing the usual insulators well, he is very enthusiastic about this healthy resource; Previously, he “in (a) puff of dust”, he explains, jumping on the blocks to drive them into the structure, proof of their great solidity.

The choice of card has won Nicolas Le Dirach three years ago. After looking at a documentary on its properties, the carpenter was closer to it and discovered a product already marketed based on recycled cardboard and intended for construction. Nicolas trained in its use and used it for the roof, the floor and the walls of his own home. A hundred square meters, it now serves both as an experimentation and the exhibition model of its construction company, a wooden wooden house. A decision he does not regret since, to heat himself, the entrepreneur notes having “used only 18 bags of 15 kg of pellets for the stove last year – less than 100 euros in all – to maintain a temperature of 19 ° C”.

On the acoustic side, the assessment is just as satisfactory. Inside the house, it is really necessary to hear your ear to hear the train passing at high speed a few tens of meters. Where a classic construction, in concrete block and wood wool, reduces the noise of 25 decibels, the cardboard at the attenuated by almost 45, according to the carpenter.

A design… concrete!

The secret of these performances is due to the very structure of this material designed by Alain Marboeuf, founder of Bat’ipac, at the origin of the famous IPAC blocks used by Nicolas Le Dirach. Made up of several layers of honeycomb cardboard, they are wrapped by a waterproof membrane which allows them to protect them and lock up the air, a key element of insulation.

Another interest in these “cardboard breads”, their environmental added value: almost all of the raw material comes from recycled and recyclable resources. The waterproof protection is made from plastic bottle waste and the cardboard comes directly from our yellow trash cans and can be recycled up to 25 times.

Collected in France, it is cleaned and transformed into paste, then into honeycomb leaves without adding raw material. They are then stacked and glued using a dietary glue based on corn starch to create the 10 to 25 cm thick blocks, depending on their future use (roof, wall or floor).

This step is provided by workers with disabilities in an integration structure near Nantes (Loire-Atlantique). An essential point for Alain Marboeuf, who wanted to anchor his approach “in a circular economy model and give it a societal impact”, and an additional asset for manufacturers.

A market that is a hit

These hours of integration work are increasingly counting for large companies, which now have legal obligations in matters of social and environmental responsibility. Added to the ecological character of the material and its performance, they probably explain the enthusiasm that the box has started to arouse for two years.

A first completion for Alain Marboeuf who, after twelve years and 17,000 m2 of isolated buildings, sees his project crossing a course with the entrance to the mass market. Its product convinces both individuals and professionals. The social landlords themselves seated: Brest Métropole Habitat was the first of them, with six houses ordered in 2023.

As for Nicolas Le Dirach, he had only built five annexes last year. But for 2025, his agenda is already full with five full houses, two extensions and the requests flock two to three per week. From the first house of a few tens of square meters built in 2013 to the collective set of thirty dwellings planned for this year in Auxerre (Yonne), the evolution of the orders shows: the cardboard box.