5,000 m² reimagined: urban farming on the roof of a shopping centre

Erfolgreiche Transformation einer Dachfläche

The renewal project in Noisy-le-Grand demonstrates the potential of previously unused roof spaces: an urban garden has been created on top of the multi-storey shopping centre, which produces fruit and vegetables. A local catering service ensures that healthy meals, particularly fresh salads, are prepared and delivered daily by cargo bikes. In addition, workshops, talks and events focusing on the environment, agriculture and food are offered. The project is part of a comprehensive neighbourhood development scheme and stems from a call for tenders by the city, which was won by ‘Ma Salade à Toit’ (English: My Salad on the Roof).

Complex renovation in a dense, urban setting

First of all, the existing roof structure had to be completely dismantled. This phase alone was logistically challenging: the work took place on a roof surface some 20 metres above ground level, in a densely built-up area and amidst heavy city traffic. Furthermore, the dismantled material could only be removed via a single hatch.

Inverted roof system using JACKODUR® EVO as the technical basis

JACKODUR® EVO 300, with a thickness of 150 mm, was used for the new roof structure. The thermal insulation, made from extruded polystyrene foam (XPS), offers a constant lambda value of λD = 0.032 W/(m·K) across all thicknesses from 40 to 400 mm. Key properties and benefits include high compressive strength, resistance to moisture, and rapid single-layer installation up to 400 mm, which can be carried out regardless of weather conditions. This construction method is particularly interesting for green flat roofs as an inverted roof, because the insulation lies above the roofing membrane and reliably protects it from thermal and mechanical stresses. This creates the basis for long-lasting and permanently usable roof spaces.

Following the installation of JACKODUR® EVO together with the water-draining and position-stabilising JACKODUR® filter layer WA, a lightweight substrate layer approximately 40 cm thick—specially developed for green roofs—was laid. This consists, amongst other things, of mussel and oyster shells, coffee grounds, broken bricks, wood fibres and bark. A second, more organic substrate layer completes the structure to optimise growing conditions and yield.

Work is progressing rapidly on the building site

The insulation boards were hoisted onto the roof by crane and, thanks to their light weight, were easy to work with once in place. The single-layer installation of the boards helped to ensure an efficient construction process. Clément Jahan from the contractor SMAC describes the collaboration as follows: “We now regularly work with the inverted roof solutions developed by JACKON Insulation by BEWI. In addition to the very straightforward on-site installation, we particularly appreciate the team’s availability and responsiveness – this is especially valuable on complex construction sites.”

Grégory Shepard, founder of “Ma salade à toit”, emphasises the project’s core objectives: “We use agroecological techniques to create an urban vegetable garden that is productive whilst also pursuing a clear environmental goal.” The project thus demonstrates the potential of unused rooftops when a robust inverted roof structure, high thermal insulation and a productive new use are consistently combined.

Images for the message

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  Image 1 / 5: An urban farming project has been established across a roof area of around 5,000 m²: the unused roof space has been transformed into a productive urban space suitable for agriculture through the installation of a robust inverted roof system. Image: Ma Salade à Toit
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  Image 2 / 5: Die Wärmedämmung JACKODUR® EVO 300 wird im Zuge der umfassenden Sanierung auf dem Dach des Einkaufszentrums in Noisy-le-Grand verlegt. Bild: Ma Salade à Toit
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  Image 3 / 5: View of the roof surface during renovation: the single-layer JACKODUR® EVO thermal insulation, together with the JACKODUR® WAfilter layer, forms a stable foundation for future use. Image: Ma Salade à Toit
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  Image 4 / 5: A substrate mix specially developed for green roofs is laid. This marks the start of the visible transformation into a green roof landscape. Image: Ma Salade à Toit
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  Image 5 / 5: Fruit and vegetables are grown on the roof to supply the local community – an example of the huge potential of previously unused roof space. Image: Ma Salade à Toit