atlas@eurac.edu
GENERAL INFORMATION RENOVATION PROCESS RETROFIT SOLUTIONS EVALUATION

Timber-framed barn in the north of France

60220

SAINT-SAMSON-LA-POTERIE, France


Owner

Guillaume ALGLAVE
60220 SAINT-SAMSON-LA-POTERIE (FRANCE)

Contact Details

Elodie HEBERLE
Cerema
elodie.heberle@cerema.fr
(+33)3 88 77 79 31

Other Information

Related publications
http://www.rehabilitation-bati-ancien.fr/fr/retours-d-experiences/reconversion-dune-grange-seigneuriale-en-logement-performant-0
Overview, courtesy of Cerema
This timber-framed building is located in Saint-Samson-la-Poterie in the Oise region (northern France), over Paris, and especially in the natural region called "Pays de Bray". It was the barn of a landlord housing of the 17th century and it has recently been retrofitted and restored by the owner himself. A careful work on the materials and on the execution was made. The barn is one of the case studies of the CREBA (French knowledge center for responsible retrofit of heritage building) website.
GENERAL INFORMATION RENOVATION PROCESS RETROFIT SOLUTIONS EVALUATION
Energy performance
55 kWh/m2.y

Climate Zone Cfb

Altitude 198 m a.s.l.

HDD 1901

CDD 524

Protection level Not listed

Conservation Area:
No

Level of Protection:

Building age 1700-1800

Year of last renovation:
1700

Year of previous renovation:
1700

Building use Residential (rural)

Secondary use:
NA

Building occupancy:
Permanently occupied

Number of occupants/users:
4

Building area Net floor area [m²]: 400,0

Building typology:
Detached house

Number of floors:
3

Basement yes/no:
No

Number of heated floors:
3

Gross floor area [m²]:
400,0

Thermal envelope area [m²]:
1000,0

Volume [m³]:
1000,0

NFA calculation method:
SHON (fr)

Construction type
Timber frame

External finish:
Rendered

Internal finish:
Plastered (on substructure)

Roof type:
Pitched roof

+ MORE - LESS
Overview, courtesy of Cerema
Overview, courtesy of Cerema
Before intervention, courtesy of Guillaume ALGLAVE
Before intervention, courtesy of Guillaume ALGLAVE
Housing plan, courtesy of Guillaume ALGLAVE
Housing plan, courtesy of Guillaume ALGLAVE
Street facing façade, courtesy of Cerema
Street facing façade, courtesy of Cerema
One edge of the east façade, courtesy of Cerema
One edge of the east façade, courtesy of Cerema
Original framework, courtesy of Guillaume ALGLAVE
Original framework, courtesy of Guillaume ALGLAVE

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

This building is located in Saint-Samson-la-Poterie, a village of 250 inhabitants in northern France, 140 km away from Paris. The storeys are timber-framed, filled with cob.
Heritage Assessment Files
Mass lay-out, courtesy of Guillaume ALGLAVE
Mass lay-out, courtesy of Guillaume ALGLAVE
Aerial view, Google Maps
Aerial view, Google Maps

State of repair

Conditions of the envelope
Before intervention, the barn was inhabitable because of its agricultural use. It was entirely empty, without floors, doors and windows. The original framework was in good condition but needed a few reparations. However, the cob was in very bad state and was partially missing. Some pieces of the wooden-frame were also mouldered by lack of maintenance, especially wall plates and wooden poles, and had to be replaced. The barn was thus very vulnerable to climatic variations. There was no rising damp at all, thanks to the situation of the building on the highest point of the village.
Description of pre-intervention building services
There was no heating and no domestic hot water.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION
The landlord housing was built in the 17th century but the manor house and many outbuildings were destroyed. The barn, few outbuildings and the ruins of a round dovecote are the only buildings left. The street facing façade is west-oriented, the most subjected to rain. Its higher part is covered with a slate cladding. The lower part is protected by a canopy, aiming at moving away storm water from the cob. Vertical wooden cladding are covering the edges of the east façade. They once were painted in a raspberry red colour. The framework has three levels and is a remarkable element of this barn. It has been restored as it was originally. The few remaining outbuildings were transformed into garage or garden shed. This type of barn is more and more rare but still present in the landscape of this rural region.
Heritage Value Assesment
As a passionnate about heritage, the owner is active in a local heritage protection association. He had access to documents that describe the architecture of this type of barn.

Aim of retrofit

Renovation
The retrofitting project lasted from 2010 to 2016. The owner works in the construction sector. He used to restore rural buildings in the past and runs now the terracotta manufacture of Saint-Samson-la-Poterie, in operation since 1836, from which the village got its name. The manufacture uses the clay of the "Pays de Bray". One particular objective of this project was to prove, by a real example, that it is possible to save this kind of rural heritage buildings, often destroyed otherwise and replaced by new buildings. The owner wanted to restore the exterior of the barn, but also to achieve a good energy performance in order to live in there. The housing offers indeed 400 m² of habitable surface. As the interior of the barn was completely empty, the owner was free to arrange it as he wanted and opted for a modern design but needed to be creative because his budget was tight. He also wanted to promote local and biobased materials, especially the ones from his manufacture and local craftspeople. He thus carried out the work alone with five local carpenters, with some help of the local heritage protection association. This project was reported in numerous regional press articles and obtained a label and awarded a national grant for the quality of the exterior works related to heritage.
Was there any change of use?
It was a hay barn, built in the 17th century on the highest point of the village. Until recently, it was used as such.
Stakeholders Involvement
Private Sector
Guillaume ALGLAVE
60220 SAINT-SAMSON-LA-POTERIE
Tools used
Was the renovation process done following a specific methodology? No
Energy calculation There was no energy calculation. Insulation thicknesses were chosen to fit the French low energy building ("Bâtiment basse consommation") label requirements.
Other Studies were conducted in order to choose the heating system, including geothermal heating.
20190925_CREBA_Retour_d_experiences_Saint-Samson_la_Poterie.pdf

RETROFIT SOLUTIONS

External Walls

Timber-framed walls filled with cob

Timber-framed walls filled with cob

The ground floor and the first storey were insulated from the interior with 20 cm of hemp wool on wood frame. The insulation was rendered, as traditionally, with the earth from the manufacture, clay rich, on chestnut laths. No airtightness membrane was installed because the render is naturally airtight when well dosed and well executed. Besides, the render was assumed by the owner to be a sufficient vapour barrier. In fact, it is not the case and the installation of a vapour barrier or the use of another insulations solutions could have avoided internal condensation in the walls. The exterior façades were rendered with a lime and clay plaster. Between the wooden frame and the render, the plaster is being processed at 45° to the outside. This allows the wind-driven rain to be evacuated away from the wooden frame. All renders were executed in Spring, in order to let them dry long enough.

The stone substructure and some part of the wooden frame were cleaned and repaired. The street facing façade was rebuilt as it was before. The main entrance, on the east façade, had been enlarged for the passage of tractors. It was narrowed in order to look like it was, thanks to old drawings. All the old cob was removed and replaced by new one, made of clay, sand and straw and laid on laths nailed in the wooden frame. The wooden frame was painted in a raspberry red colour, that was advised by the Oise council of architecture, urban planning and the environment (CAUE), a non-profit consulting organisation present in every French department. All the interior renders were coloured with natural pigments. More than ten different pigments were used in the housing. Wooden panels are covering the lower part of the walls.

Wooden frame with new cob, courtesy of Guillaume ALGLAVE
Wooden frame with new cob, courtesy of Guillaume ALGLAVE
Wooden frame without cob, courtesy of Guillaume ALGLAVE
Plan of the east façade, courtesy of Guillaume ALGLAVE
Chesnut laths, courtesy of Guillaume ALGLAVE
Plan of the east façade, courtesy of Guillaume ALGLAVE
Chesnut laths, courtesy of Guillaume ALGLAVE
U-value (post-intervention) [W/m2K]: 0,4 W/m²K
More Details
Original wall build-up
Plaster - Earth coating:
 20 mm
Other - Old cob or missing:
 140 mm
Plaster - Earth coating:
 20 mm
Retrofitted wall build-up
Plaster - Earth coating:
 20mm
Insulation - Hemp wool insulation:
 200 mm
Other - New cob:
 140 mm
Plaster - Earth coating:
 20 mm


Windows

Wooden double-glass window

Wooden double-glass window

The barn did not originally have windows. About twenty openings were created on both façades, respecting dimension, location and rythm that can be found in other similar buildings.

The windows are all wooden double-glass windows. The wooden front door was tailor-made by a local craftsman.

Overview, courtesy of Cerema
Overview, courtesy of Cerema
Existing window U-value Glass [W/m2K]: 5,0 New window U-value Glass[W/m2K]: 1,3 Existing window U-value Frame [W/m2K]: 5,0 New window U-value Frame [W/m2K]: 1,3
More Details
Existing window type No window
Existing glazing type No window
Existing shading type NA
Approximate installation year 1700
New window type Box-type window
New glazing type Double
New shading type Outer shutter
New window solar factor g [-] 0,63

Other interventions

ROOF

GROUND FLOOR

OTHER

ROOF

To be repaired by the carpenters, the framework was entirely lifted with jacks.

The dormer windows were dismantled then reassembled as they were. The second storey with its slopping ceilings was insulated with 30 cm of hemp wool with a vapour barrier and covered with classic plasterboard. A ventilated and high vapour permeable rainscreen was installed between the insulation and the slate, with an air gap of 4 cm.

Lifted framework, courtesy of Guillaume ALGLAVE
U-value (post-intervention) [W/m2K] 0,14
More Details
Original roof build-up
Slate - Slate:
 3 mm
Other - Framework:
 400 mm
Retrofitted roof build-up
Slate - Slate:
 3 mm
Other - Framework:
 40 mm
Other - Ventilated and high vapour permeable rainscreen:
 1 mm
Other - Hemp wool insulation:
 300 mm
Other - Vapour barrier:
 1 mm
Other - Plasterboard:
 13 mm
GROUND FLOOR

On the ground, a polyane film was spread in order to form a moisture barrier. Polystyrene was installed above and goes up the wall until it reaches the wall insulation, in order to avoid thermal bridges. Then a classic concrete slab was poured and a radiant floor heating was installed.

A new flooring of 3 cm thickness with reused terracotta tiles, slate from the Touraine region, bricks and wooden floor was created. Some of the tiles unfortunately cracked because of an application failure.

Reused tiles, courtesy of Cerema
Reused tiles, courtesy of Cerema
U-value (post-intervention) [W/m2K] 0,6
More Details
Original groundfloor build-up
Other - Earth:
 20 mm
Other - Earth:
 20 mm
Retrofitted groundfloor build-up
Finish - Reused tiles:
 30 mm
Other - Radiant floor heating:
 100 mm
Concrete slab - Concrete slab:
 20 mm
Insulation - Polystyrene:
 100 mm
Insulation - Polystyrene:
 100 mm
Damp Proof Membrane - Polyane film:
 1 mm
OTHER

An intermediate floor was created with local wood. The wooden beams are not embedded in all the depth of the wall, so there are few thermal bridges.

The interior was very carefully designed and honours reused materials (tiles but also doors and furnitures). To access the second storey, a wood and zinc stairwell was created.

First storey, courtesy of Cerema
First storey, courtesy of Cerema

HVAC

HEATING

VENTILATION

HEATING

Studies were conducted in order to choose the heating system, including geothermal heating. But the studied systems were beyond budget. The owner simply opted for a second-hand oil-fired boiler, that provides both heating and domestic hot water.

There are no radiator since the only heat emitter is the radiant floor heating from the ground floor. As the intermediate floor is not insulated and features a large hopper, the warmth from the ground floor can rise in the upper storeys and the radiating floor heating turns out to be sufficient to heat the 400 m² of the housing.

More Details
New primary heating system
New system type Boiler
Fuel Oil
Distribuition system Radiating floor
Nominal power kW
VENTILATION

The owner planned to install a single flow ventilation system : laying of ducting and air inlets in the windows. Until it is put into service, the housing is ventilated by opening windows, which is not satisfactory regarding the ventilation law in France. Indeed, it requires a permanent ventilation, even for retrofitted buildings.

Earth render also helps to keep indoor air quality to an acceptable level, as it can absorb water up to 7 % of his weight.

More Details
Original roof build-up New ventilation system
Type ventilation system Centralized
Type flow regime Overflow
Heat recovery No
Humitidy recovery No
Nominal power kW
Electric power kW
Control system

Energy Efficiency

Energy Performance
Energy performance certificate: No calculation was performed. But considering that the owner spent 2000 € a year for heating and domestic hot water, that 1 L of fuel oil is 0,90 cents worth and that the calorific value of it is 9.97 kWh/L, the annual energy consumption is 55 kWh/m².an. To compare, to obtain the French low energy building ("Bâtiment basse consommation") label, the consumption for heat, domestic hot water, ventilation, lighting and pumps must be lower than 104 kWh.m².year in primary energy. Note that the owner and his family are environtmentally conscious and try to save energy.
Voluntary certificates: No
Energy Use
Consumption_estimation_After: 55 kWh/m2.y

Primary Energy

Internal Climate

Temperature

The owner and his family are fully satisfied of the thermal comfort of their housing in both summer and winter.

Costs

Financial Aspects

Works extended over six years and were mostly carried out by the owner himself. A cost estimation is indeed very difficult to make. The restoration obtained a national grant that funded 1 % of the total costs of the exterior works related to heritage (tiles, roofs, framework, exterior render, etc) and that allowed the owner to get a tax credit amounting 25 % of these costs.

Running Costs
Annual heating cost
2000 € (total)
(includes DHW) Yes