The Silhac Hut

  • Building Type : Isolated or semi-detached house
  • Construction Year : 2018
  • Delivery year : 2020
  • Address 1 - street : 553 route du Chiat 07240 SILHAC, France
  • Climate zone : [Cfb] Marine Mild Winter, warm summer, no dry season.

  • Net Floor Area : 66 m2
  • Construction/refurbishment cost : 68 619 €
  • Cost/m2 : 1039.68 €/m2
  • Primary energy need :
    (Calculation method : )
Energy consumption
Economical buildingBuilding
< 50A
51 à 90B
91 à 150C
151 à 230D
231 à 330E
331 à 450F
> 450G
Energy-intensive building

The Cabane de Silhac is a micro-house whose history is intimately linked to the designer and inhabitant that I am, Celia Auzou.

In 2016, after 8 years of rather conventional architectural practice in an agency, I was bored and frustrated by the lack of practice and conviction I encountered around my profession. I then decided to carry out a personal project allowing me to achieve several objectives simultaneously : to live in a place of "refuge" in nature, to live fully a building site, to self-build, to confront my ideas of eco-responsibility with reality, to implement and to have implemented materials of reuse.

To do this, after many sketches, I produced a project that conquered me. The house envisaged is very compact since it is a simple volume, parallelepipedic, of 36m² livable. In order to deceive this reduced surface, the height under rampant is of 3m on average and the surface of the stay reaches 27m ². To manage the steep slope of the land (welcome to the Ardèche) and to find a place for DIY and storage, the house has a workshop under its living space. The 36m² and their terrace are thus suspended above the surrounding forest. At this stage, the main lines are drawn.

The will to work with reused materials implies to adapt to the already existing. The small size of the house, already frugal in itself, facilitates the integration of these materials. Thus, the exterior woodwork, interior woodwork, electrical equipment, the terrace, the wall and ceiling cladding, the frameworks of the partitions and the joists, the stove, the sanitary elements, the furniture and the household appliances, and the landscaping of the exteriors are all subjects carried out in reuse. It is 14 tons of materials which are reused on the micro-house and in its external arrangements.

If you had to do it again?

Having now the adequate local network, I would consider finding reused wood for the frame, thus strongly reducing the impact of the building and pushing the experimentation further. Other items such as insulation and wood cladding for the facades would also be sourced from reuse. On the design side, I don't think anything would change. Perhaps, the building would be 20 cm wider for a little more space in the kitchen and on the side of the bed in the bedroom.

See more details about this project

Photo credit

Célia Auzou


    Célia Auzou

    0760225580, celia.auzou[a]

Construction Manager

    Célia Auzou

    0760225580 / celia.auzou[a]




    François-Pierre MOURGUES



    Romuald MARTEL




    Joanne BOACHON

    Supplier of reused materials

    Assistance to the Contracting Authority

    Re.Source Réemploi

    Célia Auzou

    AMO reemployment

Contracting method

Separate batches

Energy consumption

    There has never been an Energy Audit of the building or DPE.

Real final energy consumption

    3 984,00 kWhef/

    110,00 kWhef/

    2 021


    • Wood boiler
    • Individual electric boiler
    • No cooling system
    • Single flow
    • No renewable energy systems

Construction and exploitation costs

  • 68 619

Urban environment

The house is in the middle of nature, in the hamlet Le Chiat which gathers about ten houses, on the commune of Silhac in Ardèche (07) of 300 inhabitants.

Land plot area

2 000,00 m2

Built-up area

40,00 %

Parking spaces

1 spot

Building Environmental Quality

  • indoor air quality and health
  • comfort (visual, olfactive, thermal)
  • waste management (related to activity)
  • building end of life management
  • integration in the land
  • building process
  • products and materials

Reuse : same function or different function

    • Indoor joineries
    • Outdoor joineries
    • Partitions
    • Electricity
    • Landscaping
    • others...

    The elements made in reuse :

    • 10 exterior joineries, 9 of which are second-hand from careful deconstructions, order errors and exhibition pieces (see joinery plan). Lot 2680€ including transport (+1350€ of installation in total) ; 
    • interior woodwork : for example, the two kitchen worktops made of two sheets of medium wood recovered from the material library, as well as the second-hand tiles that cover them, or the shower room vanity top made of trespa (which falls from the front and is therefore waterproof) + the vanity unit under the vanity top made from an old chest of drawers. We can also mention the baseboards from a surplus of construction site (40ml). Lot 190€ including transport ;
    • electrical equipment, i.e. all switches, sockets and lights. Lot 10€ including transport ;
    • the terrace, more specifically the wooden slats up to 40 m² collected (via the good corner), cleaned, recut and turned over to be put back in place for 32m², south and north. Lot 150€ including transport ;
    • the wall and ceiling covering is from the 2017 architecture biennial (Atelier Utopies) which took place at the Sucrière in Lyon. The implementation of the scenography having been thought upstream as "non-destructive", the boards and wooden slats were linked by rope. Thus, they were virgin and suitable for reuse. They are 100u. of pine panels (2000 mm x 500 mm x 18 mm thick) and cover all the peripheral walls of the house as well as the ceilings of the 3 rooms. In order to limit the falls, the layout was made according to their dimension, limiting drastically the falls. Lot 350€ including transport ;
    • the frames of the partitions and the joists, are from the same sourcing as the pine panels. They are 85u. of pine cleats (32 mm x 45 mm x 4500 mm). They receive the panels of the walls, the ceilings and the massive parquet of the ground, while offering the adequate technical space for the passage of the networks. Lot 400€ transport included ;
    • the stove and its floor plate, acquired second hand in the village of Silhac, from an acquaintance. I acquired the smallest one I found second hand (from an acquaintance) in order not to overconsume. It makes 4kw and I spend one stere of wood per year (my neighbor cuts it, makes it dry then cuts it for me) to heat the volume in the cold period. Lot 330€ transport included (+1500€ of installation in total with supply conduit and exit in roof) ;
    • the sanitary elements, which are the sink, the kitchen sink, the taps from private individuals Le Bon Coin. Lot 110€ including transport ;
    • the ventilation grids / air inlets from a private individual Le Bon Coin. Lot 30€ transport included ;
    • the painting of the walls is resulting from funds of pots of professional painters. Lot 10€ transport included ;
    • furniture and household appliances (sofa, desk, chairs, tables, bed, oven, fridge, hotplates, dishwasher, etc.) from Le Bon Coin. Lot 2600€ including transport ;
    • the exterior design, in particular the exterior staircase in mixed technique: high steps in chestnut beams from the deconstruction of an inn in the neighboring village and low steps in stones from the ground, from fallen dry stone walls. The already there takes all its sense. We can add the works in progress at present that are a wooden fence in bastaings resulting from the deconstruction of a wooden slab in the French style and the installation of 3 tanks of water recovery (of 1000L each). Lot 200€ including transport.

Sustainable design

    The 3 materials are :

    1/ the exterior woodwork ; they came from many different sources (see previous category). They were stored at the carpenter's who was able to build the house around their dimensions by having them on site at his workshop. He also made the pre-frames to measure for each of them. It is another craftsman who installed the woodwork. He was not in favor of installing them because he felt he was out of line with his insurance. He notified his invoice that the woodwork he installed was not his doing. 

    I think that some of them (notably the two lapeyres) are really light (in their structure) and would not have deserved a second life in a new construction but rather in a bio-climatic greenhouse or a double skin. Their joints have been partly removed since then and will be changed soon. These are the ones I plan to get rid of in the next 5/6 years.

    2/ the interior wood coverings ; they are from the Lyon Biennial of Architecture (see previous category). It is the association Minéka which captured the deposit (just like the one of the cleats) and which redistributed it at solidarity price. The implementation was carried out in self-construction. In their majority, they were not recut to limit the falls and the support cleats were posed consequently. For the ceiling, they were installed with a plate lifter (rented for the occasion). They are simply screwed to the brackets in order to be removable at any time. The immense interest that I see there is double:

    • I can dig in the wall, that is to say for example to take out the insulation if I had a plate of wood wool which is damaged, or to take again the electric networks passing by there if need be, without having to enter in big works of platrerie. There is only to "close the box" when the intervention is finished.
    • in the long run, the plates (as well as the cleats) can be reused without difficulty for a third life.

    3/ the plumbing elements ; they come from the good corner. They are old and it was complex to find the bungs, siphons, fittings corresponding. They were also installed in self-construction. They specifically required to be resourceful / handyman / creative to be made usable and durable.

    This notion appeared as the construction progressed, the more I dug into the notion of reuse in parallel. I also discovered the BAZED reference system at the same time.

    As such, the frameworks of the partitions and linings are made of wooden strips, screwed together and on the main wooden framework. Almost all the walls are removable (because just screwed as explained above). To do this, the baseboards are also screwed. Many elements are removable (you just have to lift the cupboard doors (made of 3 wooden folds) to recover them and take them to another project). The parquet floor as well as the cladding is pointed (point 1mm diam.) only in the tongues to be able to recover at least the wood. The insulating sheet follows the same pattern as the rest. Except in case of obvious impossibility of mechanical link, everything is under this format.

    The wood frame of the house as well as the siding are new. The carpenter got the wood from a nearby sawmill (I don't remember the details). Concrete was used (in the right places) to maintain the land at the foot of the house and to become a workshop storage space. It was used as a base for the wood frame. Originally, techno-piles were considered but the slope of the land is so steep (16m difference between the top and bottom of the land) that this solution was abandoned.

    Moreover, the house has been insulated with ISONAT & STEICO wood wool mix. The roof is in steel tank.

Environmental assessment

    Outdoor facilities 2840.214264 31.81952695 6441.51221
    Exterior fittings / Locksmithing - Metalwork 0 0 0
    Carpentry 1161.906667 18.58066 1008.333562
    Partitions 0 0 0
    Coverage 0 0 0
    Roofing / Exterior fittings 0 0 0
    Lighting 671.7746124 4.419368699 719.2832713
    Safety lights 0 0 0
    Climatic engineering equipment 0 0 0
    Electrical equipment 20.72221888 1.270485753 32.06175904
    Facades 0 0 0
    False ceilings 0 0 0
    False floors 0 0 0
    False ceilings 1282.759658 19.96520344 1899.93657
    Structural work 0 0 0
    Sanitary installations 196.3616837 1.79894275 144.7462377
    Insulation 0 0 0
    Exterior carpentry 1436.725045 13.95544533 1524.253577
    Interior carpentry 169.335 4.227245667 454.1590882
    Furniture 1696.350985 638.8669183 1437.140234
    Paint 16.74170246 0.446296335 15.85387955
    Plumbing 74.85 1.01805 199.9663638
    Floor coverings 47.56106948 10.1588978 98.0695322
    Floor and wall coverings 0 0 0
    Wall coverings 0 0 0
    Building security 0 0 0
    Locksmithing - metalwork 49.98493717 0.619533229 32.94360732
    VRD 0 0 0
      Avoided CO2 (kg)  Avoided water consumption (m3) Avoided waste (kg)
    TOTAL 9665.287843 747.1465743 14008.25989

    The reuse operation saved the equivalent of 77322 kilometers traveled by a small car, or 88 Paris-Nice trips, 4981 rectangular bathtubs filled with water and 28 years of household waste of a French person.

    In the calculation of the avoided impacts, I could not count :

    • the stove and its floor plate ;
    • the complementary elements to the exterior work (screws, ropes, etc.) ;
    • some furniture such as the shower room chest of drawers, the bed, the sofa and all the other small pieces of furniture / decorative elements of the cabin.

    And I counted the 100 m² of wood panels inside walls and ceilings in the category of false ceiling reconstituted wood (for lack of another more suitable category). Also, I counted the 85u of cleats and the 40 ml of pinthes under the category wood frame (for lack of another more adapted category there too).

Reproductibility and Innovation

    The owner, the architect and the project manager being one and the same person, I must admit that it greatly simplified the game of actors. It only remained to convince the companies, which, once informed did not slow down the company, without feeding it either.

    On the storage side, as previously mentioned, the storage of the joinery was done at the carpenter's. For the rest of the materials, they were stored directly in the workshop space of the building, the first space built. It should be kept in mind that the self-construction that followed the delivery of the building to the companies took two years. This long period of time allowed us to continue sourcing materials as the construction progressed. This long time also allowed us to take the time to feel the terrain, to capture the winds, the way the exterior vegetation evolves and to refine the design at the same time as the construction. This is an invaluable gain for the quality of the project (which self-builders know well).

    As for the sourcing of materials, I was in charge of that. This allowed creative back and forth with the design part and allowed to adapt the project to the various "finds". This design around the already there is alive and dynamic. It is an additional element of context that nourishes the project in the same way that the specifications or the site can be. The important thing is to keep the macro vision of the project in mind throughout this back and forth. To illustrate this exercise, the example of the joinery is obvious since it had an impact on the façade and therefore on a potential modification permit. Some of the joineries brought the idea of large fixed bays and a more continuous panorama on the hillside. Each selected joinery brings with it its history and aesthetics. It shapes the project.

    The insurance brake, on the joinery in particular, is obvious. The installer of the woodwork wished to exempt himself by noting on his invoice that he had not supplied the woodwork. I think that this note has no value because he knows the site. Other than this point, we did not investigate further. I simply accepted the risk I was taking by not having insured millwork. As for the other materials, the fact that we are in individual housing relieves us of many questions of this type. Switches and sockets, for example, do not need to be new. 

    As far as communication is concerned, I share more and more about this project, especially since the article about the ecological house which got very good feedback. The reuse trainings and interventions with public and private actors that we animate with Re.Source Réemploi allow these times of restitutions. I communicate regularly on this project (and more widely on the practice) within the network of the Beavers as well as in that of VAD, and still soon in Eurobois in June 2022 and with the CAUE on October 26 & 07, 2022.

    With my colleagues, we are thinking of expanding this feedback on other projects for which we have the design and project management in the context of our architectural practices, and for which reuse finds its place. We are enthusiastic about the REX exhibition/publication format.

Economic assessment

  • 7 056
  • 10 %

Building candidate in the category

Bâtiments résidentiels / prix de la construction neuve

Bâtiments résidentiels / prix de la construction neuve

Trophées Bâtiments Circulaires 2022

 Circular Buildings 2022 Awards
 circular economy
 materials and solutions

Author of the page

  • Célia AUZOU

    Architecte & Accompagnatrice Réemploi


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