012 's Hertogenmolens Aarschot

Restoration and extension of a 500-year-old watermill

Procedure Open Call 0516
Client NV ‘s Hertogenmolens
Surface 2325 m2
Phase completed
Date 2004 – 2010

The ‘s Hertogmolens were built at the beginning of the sixteenth century. Over a period of almost 400 years they evolved step by step into a double mill with a central lock, which formed both a bridge over the River Demer and a part of the town walls. At the end of the twentieth century the north wing burnt down and the west façade of the complex collapsed. The bridge was closed. So the mills had remained as a ruin on an inaccessible site in the town for more than 20 years, making their restoration and re-use a matter of urgency.

Despite having a building history covering several centuries, the materials used have always remained unambiguous: a plinth with alternating bands of white stone and the characteristic local Diestian ferruginous sandstone, facades in red brick and slate roofs. Time had given the ensemble a monolithic appearance. The west façade with its weathered wooden boards had in the meantime become a familiar sight. We decided not to rebuild in masonry, even though it is perfectly well known what the original building was like. Our basic principle was to focus on the entire history of the complex.

The northern extension on the island was rebuilt following the original outline, but now as a concrete volume cast in situ. Iron oxide was added to the concrete so that the colour would change to a rust-brown akin to the colour of the Diestian stone in the plinth. The window openings retain the original proportions, but no longer stick to a strict grid pattern. The west façade is in the form of a steel construction clad on both sides, on the inside with wooden boards, and on the outside with sheets of Corten steel. On the one hand this format was used as a reference to the long-term deterioration of the façade (and the time when it was boarded up) while on the other the colour of the corroded metal relates to the whole. The material used for the new facades already displayed the required weathering. The new and existing parts enhance each other’s individual character. The distinction is clear, but their mutual affinity is equally so.

This monument will now be used as a hotel, brasserie and function room. The final stage of the restoration will be the reactivation of the water-power that was the building’s original purpose, but it will be essential to install new machinery. The feasibility of this and the effects upstream are being studied.