- Some addresses
- Natural materials
- The choice of tradition
- You want to insulate your attic at € 1?
- The raw brick
- A standardized building material
- The rammed earth and the mud
- The technique of adobe
- The daub
- Project the daub
- Vegetable and animal fibers
- Prepare the hemp mortar
- Use hemp
- Hemp conglomerate
- The virgin wool of sheep
- Bridging the interstices
- Wool rolls
After a century of reigning concrete and synthetic insulation, natural materials find favor with a public in search of well-being and safety. Of mineral origin, vegetable or animal, recyclable and respectful of the environment, they offer many possibilities of uses and astonishing properties.
- Guy Thuau House, ZI La Chaonnerie,
Tel.: 02 51 65 05 88.
Sale of cork, hemp, untreated chestnut parquet, natural paints...
- Center for culture and earth technique,
Phone: +33 (0) 1 61 84 50 04
(internships and trainings).
- CRAterre Training Center,
60, Constantine Avenue,
38036 Grenoble Cedex 2.
Tel.: 04 76 40 14 39.
- Domus, BP 50, 09120 Varilhes.
Phone: 05 61 67 73 45
Phone: 04 76 07 42 05
(construction and earthmoving company)
- Giza, land of the future,
Phone: 04 74 26 55 61
- The Chanvrière de l'Aube,
rue du General-de-Gaulle,
Tel.: 03 25 92 31 92
- The Chanvrière du Belon, Kermpicard,
Tel.: 02 98 06 45 34
- Oak cork,
74, Montparnasse Boulevard,
Tel.: 01 43 22 02 15
Attention, this notebook was made in 2002. Some addresses may not be more valid.
Between house, office and public spaces, we live the 4 / 5th of our time in buildings! This is probably why (taking into account the problem of asbestos and its considerable cost), we more easily establish the link between health and quality of construction. Similarly, we are now more sensitive to the consequences of soil and air pollution caused by the production of prefabricated and synthetic materials. Hence the renewed interest in natural materials, pleasant to handle and non-irritating, which emit neither dust nor harmful gases both during their manufacture and their installation.
The choice of tradition
Employed for millennia to build, decorate and sanitize, natural materials draw their raw materials from the local soil. Indispensable for long-lasting renovation of old homes, raw brick, mud, cob and lime are also used to build and develop healthy, cheap.
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The raw brick
In the Midi-Pyrénées and Rhône-Alpes regions, there are houses, farmhouses and raw brick farmhouses. Their masonry is made of blocks of clay added sand and chippings molded in wooden lockers and then dried in the sun. Invented in the seventh millennium in Asia Minor, this brick (called adobe) is the oldest "standardized" building material in the world. The Egyptians, Romans, Chinese and the peoples of Central and South America will use it massively to build their temples and their homes.
The adobe has since been replaced by "compressed clay earthenware", with resistance and insulation reinforced by the addition of lime and wood chips. Thanks to its thermal inertia and its moisture behavior, houses enjoy a more stable temperature, summer and winter, thus proving easier and more economical to heat.
Like fired brick, raw brick is laid in horizontal rows but must be protected by an exterior rendering, the clay being sensitive to water runoff. You can buy it (about 32 € / m2) or produce it yourself if you have clay soil, a mixer and mussels. Among other possibilities, it is also used for the manufacture of partitions, kitchen plans, fireplaces... or colored finish coating for bricks, plasterboard, concrete, etc.
Major manufacturers: Akterre (Claytec), Center of land.
A standardized building material
Born seven thousand years ago, raw brick is the first "standardized" building material. Made from molded clay, it is used to build facades, walls and decorative partitions.
Universal material at the base of all architectures, lime is obtained by baking at 1000° C of crushed limestone. Superseded in 1950 by the cement, it operates a net return following the disorders observed on the houses renovated with this binder: fissures, detachments of coatings, problems of humidity, not to mention a certain aesthetic coldness.
Used in paste or liquid, lime offers many qualities. It is soft, plastic and unctuous, adhering well to the support and allowing expansion movements. It is also microporous. In addition to masonry and plaster work, it can be used in whitewash or milk to decorate and clean the house.
The 40 kg bag costs between € 7.6 and € 12.2.
Major manufacturers: Saint-Astier, Batical, Arte Constructo, Calcia, Lafarge...
The rammed earth and the mud
Since the dawn of time, the earth has nourished man as much as it shelters him. In Limagne (Auvergne) and Dauphiné, there are many houses built in clay on a base of bricks or pebbles (to protect them from rising damp). Called adobe, this technique consists of erecting the walls, portions by portions, inside formwork or "banches". These are filled with a slightly clayey, sandy soil and gravel, which is then compacted with a pestle (called "lady" or "pisoir") to reduce its thickness by half. When the soil has dried, the banche (L. 2 to 3 m x H. 60 cm) is deposited to be raised further and form a new earth.
Further north, in the Cotentin, the Bessin and the country of Rennes, there is talk of "bauge" (sometimes "bait"). This process is distinguished by the addition of straw, hay or even small branches that give plasticity and avoid a withdrawal too strong. In any case, the earth is an economical and recyclable material. Thanks to its ability to store and destock heat over a very long time, it returns the water vapor inside the house in dry weather and the pump in wet weather. Sensitive to water, the adobe or mud house must however be endowed with "good boots and a good hat": that is to say, of an impermeable base, of a coating of facade to lime and a slightly advanced roof.
Main manufacturers: Akterre (Claytec importer).
The technique of adobe
Spread throughout the world, the technique of rammed earth is to erect walls all in the ground, compacted in a formwork that is moved as and when the site.
Until the 1950s, it filled the walls of most buildings in Alsace, Picardy, Normandy... Detached by brick and cement, it remains one of the few materials compatible with this habitat that isolates, lets breathe and embellishes with its ocher tones. Elastic and flexible, it follows the movements of their wooden frames and absorbs excess moisture. It is also good insulation: 10 cm of mud equivalent to 23 cm of solid brick or 50 cm of stone. A proverb recalls its capacity of thermal accumulator: "Make your house in mud, you will be warm there the winter and cool the summer".
The mud consists of a soil containing 20 to 30% of clay mixed with barley straw (or oats), which is vigorously sprayed on wooden slats so that it clings without falling. After drying, the walls receive a coating of sandy earth, lime and vegetable fibers from the grinding of flax.
Very economical, it costs around 84 € / m3 (yield 8 m2).
Main manufacturers: Allonne Brick Factory, Akterre (importer of Claytec products).
Project the daub
Used to fill the gaps between the half-timberings, the mud (mixture of clay soil and straw) is thrown by hand onto a lattice of cleats and is smoothed to the plate.
Vegetable and animal fibers
Derived from the grinding of plants, bark or shearing sheep, they are used to insulate the entire house or to form lightweight binders for masonry that regulates moisture. Here are four examples, to which should be added wood fibers and cork.
It results from the grinding of paper (newspapers, catalogs...), soaked in acid and salts to fireproof it and make it insensitive to insects and molds. Presented in flakes to be poured into cavities, panels to be placed on the floor or partitions, it is also applied by flocking technique by a specialized company.
Approximately 69 € / m3 in bulk and 19 € / m2 in panels (1.20 x 2.50 m, thickness 3.2 cm). Main manufacturers: Isofloc, Domus...
It is obtained by grinding the stems of the plant and crystallizing its sap. Its qualities are proven in terms of resistance to humidity, stability over time and thermo-acoustic insulation (summer and winter). Moreover, it is not edible by rodents and does not irritate the hands during its use. Treated rot and nonflammable (category M2), it is used in bulk to isolate the floors and the roof. Associated with lime, it consists of mortars that drain moisture, oppose the passage of cold, heat and noise.
Hemp is also used to create light floor slabs, coat facades, fill voids between the beams of a half-timbered house and build walls (in combination with sand to reinforce its strength). Approximately 84 € / m3 in bulk to isolate or make "concretes" and 6 € / m2 in roll (0.6 x 10 m, thickness 4 cm).
Main manufacturers and suppliers: Chanvrière du Belon and La Chanvrière de l'Aube (available at Effiréal and Eurovente).
Prepare the hemp mortar
Prepared in the concrete mixer, the hemp mortar is applied between the wood and well packed. Thus, he married perfectly the half-timberings and gains in resistance.
Fireproof and rendered rot-proof and impervious by a salt-based treatment, hemp finds various applications: loose between floor joists, formation of lightweight concrete.
The Chanvrière de l'Aube (distributed by Domus).
Established on a foundation of cement blocks, this timber frame house is filled with a conglomerate of hemp (thick 20 cm), compacted in a formwork.
The virgin wool of sheep
Light, fluffy and elastic, it comes mostly from Australia and New Zealand. Highly insulating and non-irritating to the skin and the respiratory tract, it is used in bulk to fill the hollow partitions and floor joistings, in rolls to isolate the floors of the lost roofs and crawling roofs (by stapling).
Hygroscopic, this wool of sheep has the advantage of being able to absorb excess moisture (up to 33% of its weight, ie 33 cl per 1 kg of wool), without losing its insulating capacity. This natural regulation of humidity between the air of the habitat and the insulation acts like a natural air conditioning. This promotes a pleasant and healthy atmosphere in the house. Approximately 40 € the bulk bag of 5 kg, 9 € / m2 in roll of 0.6 x 5 m (thickness 6 cm). Classified as flammable (from 560° C, it does not emit toxic fumes in case of fire.
Main manufacturer: Domus.
Bridging the interstices
This wool is also proposed in rolls to fill the interstices of windows and doors. Hygroscopic, it absorbs excess moisture from the house before returning it when the air becomes dry again.
Highly insulating and non-irritating, this sheep's wool is packaged in rolls (0.6 x 5 m, 6 cm thick). It clings to roofing crawls, attic floors and ceilings.
"Daemwool" from Domus.
Originally from the Orient, this herbaceous plant with blue flowers has been known since ancient times. Cultivated mainly in the Pas-de-Calais and Caux region (Normandy), its stems and seeds are the source of fiber for textiles and oil for paints. Not very demanding in nitrogen, the plant grows without fertilizer in a cycle of seven years alternating with vegetables.
While its long fibers are used for clothing purposes, its short fibers are transformed into thermal insulation after a mineral salt treatment and a fireproof treatment. Marketed in rolls or semi-rigid panels (walls and crawling roofs) as well as in bulk (filling of floors and hollow partitions), they have the capacity to absorb moisture and to restore it according to the temperature and ambient hygrometry.
About 140 € / m3 in bulk and 6 € / m2 in roll (0.60 x 10 m, 4 cm thick).
Main manufacturers: Linisol, Textinap, Setral and Domus.
Corded to form layers superimposed and then thermolated, the flax fibers are packaged in wadding, felts, rollers or semi-rigid plates intended for the insulation of the roofs and walls.
"Natilin" from Textinap.