The inside walls on the ground floors are built using wood studs, Fermacell sheets and wood fibre panels. They are 20cm thick and the construction system used is to ensure maximum sound-proofing between rooms.

• The wood studs are placed so that each side of the wall has its own stud frame independent from the other.
• One layer of Fermacell sheets is placed on one side and two layers on the other.
• Wood fibre panels are placed in between the two wood stud frames to absorb sound.

The idea behind a proper sound-proofed wall is to create a system of sound-absorption-mass. Sound hits a hard surface and part of it bounces back. Some of it still goes through and gets absorbed by the sound-absorbing material. The remainder of the sound that manages to travel all the way through will bounce back on the hard surface on the other side of the wall. Other factors come into play such as the density of the hard surfaces, absorption factor of the sound-proofing material and the thickness of all these different layers. Based on the structure of our interior walls, we hope to achieve a rating of R’w = 55 db which corresponds to what is usually required of inside walls in hospitals.

Fermacell sheets are similar to the traditional drywall sheets with a few exceptions: they are made of a mix of natural gypsum (80{86faa949d09500cfb2fb8be01edc8582822a5980221f039bd4bbebd1d0646763}), cellulose fibre (20{86faa949d09500cfb2fb8be01edc8582822a5980221f039bd4bbebd1d0646763}) from recycled paper and water. There is no other bonding agent or glue. The result is a stronger, denser (heavier) and more eco-friendly material than drywall. Although its use is becoming more and more accepted and common in France, prices remain slightly more expensive than drywall.

The initial design of the house included a heat retaining wall. The purpose of this wall is similar to a Trombe wall which is to absorb solar energy coming through a window during the day and to radiate it back into the house at night. The wall separates the kitchen from the living room and faces the three big bay windows in the living room. The effectiveness of a Trombe wall or heat retaining wall relies on the material being dense and good at accumulating heat. Bricks, mortar made of soil and sand, and stones are all good examples of heat absorbing materials. We chose stones as we have plenty of them close to the construction site and thought it would be nice to have some visible stones inside the house.