A modernist house originally designed by Belgian architect Paul Neefs has undergone a restoration by architecture studio ISM Architecten in the town of Beerse, Belgium.

Named BEEV, the home has been reconfigured and extended to enhance its functionality and efficiency while preserving its original design from 1967.

ISM Architecten's intervention sees the addition of a rooftop volume clad in metal sheeting, chosen to reflect the colours of the area's ever-changing weather.

"Ensuring that the transformation and addition paid homage to the original design's strengths was an important element and led to several design choices," explained studio founder Wim Van der Vurst.

"The addition was aligned with the original building whenever possible, maintaining a discreet presence at the rear while allowing the original design to take centre stage," Van der Vurst continued.

The late architect Neefs is best known for his modernist houses, in which he expressed his love for pure geometry such as triangles, circles and squares in both form and layout, ISM Architecten said.

The original plan of BEEV consisted of a single-storey square, with two circle segments placed at opposite corners. A central living space runs diagonally between these two segments.

Meanwhile, the bedrooms and kitchen were placed along the outer perimeter of the house but were too cramped to meet today's standards, according to the studio.

ISM Architecten's proposal makes two subtle changes to the layout of the ground floor. The kitchen is enlarged and a bedroom is moved to a new location, freeing up one of the house's characteristic curves to allow for a stair leading to the rooftop extension above.

Inside the extension, the studio aimed to establish a clear demarcation between old and new using a varied material palette of birch veneer, perforated metal and pastel hues.

"The extension comprises a scenographic collection of distinct spatial elements, each with its unique identity," said Van der Vurst.

"The interior is divided into two zones. This functional dichotomy is accentuated by the materials and colours used for the finishing of walls, floor and ceiling."

For example, mint green is used to define the wall separating the principal bedroom and bathroom from a wood-panelled anteroom.

Meanwhile, a "monolithic" integrated sink and bath unit in the bathroom has a lemon yellow hue and is paired with a grey polyutherane floor with a purple tinge.

Improving BEEV's thermal performance was another priority in the project, and the home was brought up to current standards in terms of insulation, ventilation, energy consumption and comfort.

"This project is an ode to the modernist heritage, but also a lively and critical dialogue with the challenges of our time," Van der Vurst told Dezeen.

"It is an invitation to think about the way we shape our built environment and how we can contribute to a resilient and sustainable future," he continued.

ISM Architecten is a Belgian studio founded by Koen Pauwels and Van der Vurst in 2010. BEEV has been shortlisted in the house extension category of the Dezeen Awards.

Elsewhere in Belgium, Notan Office recently completed a series of homes positioned around a communal garden on an old industrial site in Brussels and Britsom Philips added a timber-clad extension to a small rural home in Flanders.

The photography is by Luis Díaz Díaz.