Heritage renovation

  • Building Type : Isolated or semi-detached house
  • Construction Year : 1890
  • Delivery year : 2022
  • Address 1 - street : Le Costil 61470 LE SAP-EN-AUGE, France
  • Climate zone : [Cfb] Marine Mild Winter, warm summer, no dry season.

  • Net Floor Area : 89 m2
  • Construction/refurbishment cost : 380 000 €
  • Number of Dwelling : 1 Dwelling
  • Cost/m2 : 4269.66 €/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

This project won the Low-Tech Prize of the Green Solutions Awards France 2022-2023.

Article D'A - n° 297 - April 2022

"The meeting with a private individual who had acquired a vast estate, consisting of a dilapidated manor house and its outbuildings, at Sap-en-Auge, in the Orne region, gave the team the opportunity to express its own vision, in complete freedom. "To get out of the regulatory framework, to test totally non-standard techniques, not always insurable, with 100% local materials", they claim in unison.

They very quickly convinced the owners not to undertake the long and costly renovation of the manor house, but rather to transform the adjoining 90 m2 farmhouse into a holiday home, which would allow them to consider the possible transformation of the estate over time. To do this, they propose to remove some of the bricks from the farmhouse, and then to build a wooden volume in its heart on the first floor, in order to accommodate a simple programme: a cathedral living room extended by an open kitchen, which is itself overlooked by a mezzanine office. The new wooden volume houses the bedrooms on two levels. 


Located in a rural area, the project to renovate the farmhouse - which is intended to be a short circuit - requires a physical presence in the area. Consulting the available companies and craftsmen, then creating a close relationship with the inhabitants and elected representatives requires a long-term involvement, to the point that the architects literally camped out on site for several months. They draw a map of the region, within a radius of 100 to 150 km, a map born of a clearing and meshing of both material and human potential. This long sourcing process precedes the architectural project. 

Their research into how to make the most of their know-how leads them to innovate, in a form of rural hacking. The craftsman who harvests chestnut branches on horseback and makes horticultural ganivelles is asked to make the house's cladding. The hemp industry and agricultural machinery are involved in insulating the roof slopes and in spraying 15 cm of hemp-lime insulation onto the walls. The hemp-lime spraying machine is equipped with larger nozzles to accommodate this type of mixture. The intermediate floor between the night spaces is made with 700 cattails, a mixture of green wood, local soil (slurry) and agricultural hay. The cattails were installed for a week by 15 volunteers - the only time the site was open to the public. Inspired by the traditional half-timbering of the Auge region, the framework is made of Douglas fir, surrounded by reused bricks, cleaned on site.

The whole of the wooden volume in G+1 rests on foundations without concrete or reinforcement. Technically, this is one of the most sensitive and experimental points of the project: the architects drove 12 black locust piles 3 metres long and 30 cm in diameter into the ground. The logs were manually debarked with planes and burned on the surface to become rot-proof. The piles were driven into the ground with an agricultural auger and rammed to a depth of about 2.5 metres. Finally, the heads were planed to the required level to accommodate the cyclopean foundations made of lime and flint only, thus allowing the creation of a ventilated hedgehog. The black locust was supplied by Forestiers Associés, a small family sawmill that also manages the rational logging of local forests within a radius of less than 30 km.

100% local renovation of a house in Costil with materials exclusively from the Pays d'Auge area:

  • Reused clay bricks [0 km].
  • Acacia wood pile foundations [40 km].
  • Douglas fir framework [30 km]
  • Hemp wool and hemp soil insulation [50 km]
  • Rot-proof insulation made of reused cork stoppers [30 km]
  • Cattails and raw earth plaster [0 km]
  • Cladding in chestnut poles [120 km]
  • Flooring in reused oak paving stones [220 km]

Renovation carried out by :

  • Owner: SCI Le Costil
  • Construction manager: Anatomies d'Architecture
  • Timber frame: Depuis 1920
  • Traditional masonry: Scheck & Déco
  • Roofing : Grolleau
  • Hemp insulation: Eco-Pertica
  • Sawyer : Forestiers Associés
  • Mex : Planète Mat

Ground floor layout - The Costil

1st floor layout - The Costil

AA' elevation - The Costil

BB' elevation - The Costil

Building users opinion

Remarkable comfort of biosourced materials (insulation, phase shift, hygrometry).

See more details about this project


Photo credit

Laurent Kronental


Construction Manager



    Depuis 1920

    Wood frame + carpentry + cladding


    Scheck et Déco

    Traditional masonry + reuse of bricks + foundations + finishing coats


    Couverture Grolleau

    Slate roofing + copper + hemp wool crawling insulation



    Projection of earth-hemp insulation + supply of reused cork + supply of hemp wool


    • Wood boiler
    • Individual electric boiler
    • No cooling system
    • Single flow
    • Wood boiler

Urban environment

    The brick was reused for a harmonious integration into the surrounding landscape.

    A few km from the village of Sap-en-auge (61470), in the Pays d'Auge, the Costil is an extraordinary site of 180 ha preserved from human action since always by its steep slopes, difficult to exploit by man. The house adjoins a mansion which will be the subject of a summary renovation in the years to come in order to receive the public on issues of awareness (eco-construction, permaculture, agro-forestry, etc.).

    The house faces south and enjoys a magnificent view of the Tanneries stream below.


    Clay bricks for re-use

    Schek & Deco

    Structural work / Structure - Masonry - Facade

    The bricks for the house were sourced from a ruin close to the site on the Costil estate (200 ha) and prepared by the Schek & Deco masonry company.

Construction and exploitation costs

  • 340 000

Reuse : same function or different function

    • Structural works
    • Structural framework
    • Indoor joineries
    • Landscaping

    Reused terracotta bricks: sourced from a ruin near the construction site in the Costil area (200 ha), all the bricks used are reused by the masonry company Schek & Deco.

    Crushed cork stoppers: the insulation of the lower walls was made of cork (rot-proof) from the recovery of cork stoppers in the region and crushed by the company Eco-Pertica.

    Oak farmhouse: elements of the wooden framework have also been retained and reused in the building by the roofing company Grolleau.

    Wooden paving stones: in the living room, the floor was made with wooden paving stones from old oak joinery by Atelier R-Are.

    1. BRICKS : Existing - 0km
    2. CORK: Reuse (4.5 m3 of crushed bulk cork from cork stoppers)
    3. OAK : Reuse (existing farm / wood paving / furniture)

Environmental assessment

    To date, the candidate has not provided the information needed to carry out the environmental assessment of the project using the calculation tool.

Reasons for participating in the competition(s)

Comment relocaliser l’acte de construire sa maison ? Autrement dit, comment reconnecter l’habitat à son territoire en tenant compte de ses particularités et de ses ressources : ses matériaux, sa richesse patrimoniale, ses savoir-faire régionaux ? Et comment tirer parti de cette relocalisation pour apporter une réponse architecturale aux enjeux de l’ère anthropocène ?

Nous proposons d’aborder la construction écologique selon une approche inédite : une Anatomie d’Architecture. Il s’agit d'imaginer un projet de construction, ici la rénovation d'une dépendance au Costil dans le Pays d'Auge, en déterminant au préalable un cahier des charges très restrictif pour sourcer des matériaux locaux de types biosourcés, géosourcés ou de réemploi qui seront les fondements du projet. Notre travail porte ainsi sur la mise en lumière de ces filières locales et de ses multiples retombées positives dans son territoire afin de redonner du sens à la provenance des matériaux, aujourd'hui si lointaine et si floue pour les usagers...

Green Solutions Awards 2022-2023
 eco-renovation eco-design reuse wood renovation heritage renovation Green Solutions Awards Green Solutions Awards 2022 2023

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Author of the page

Mathis RAGER

Architecte - gérant

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