A steel staircase offsets seaweed-coloured joinery and marble surfaces inside this Belgian apartment designed by local architects Carmine Van Der Linden and Thomas Geldof.

Van Der Linden and Geldof thought using natural materials and colours would reflect the calming coastal location of the two-floor apartment, which is encircled by sand dunes and grassy banks.

In the apartment's kitchen, the splashback, shelving and panelled birch-wood cabinets have been stained a murky shade of green.

"The colour choice of the wood subtly brings in the seaweed colour from the adjacent sea and the marram grasses in the surrounding dunes," said the architects.

This green hue continues across a handful of wood-lined walls in the apartment and into the guest toilet, which is fitted with a Gris Violet marble basin.

Alga Marina marble has then been used to craft the kitchen countertops and the surface of a central prep table. It's supported underneath by interlocking silver-metal poles.

The architects blanketed the remaining surfaces throughout the apartment in white paint that leaves a clay-like textural finish, in hopes of fostering an "unconscious sense of silence and serenity".

Dark-grey terrazzo also runs across the floor.

One wall of the living room features a sequence of shelves extending up across both floors of the apartment, offering a spot for the owner to display books or cherished ornaments.

The shelves also serve as a backdrop to an open-tread spiral staircase that's made from galvanised steel. This material was specifically chosen by Van Der Linden and Geldof as they felt it has an almost pearlescent quality.

"With its extremely logical and pragmatic construction method, this object stands as a 'pièce unique' in the open living space," they explained.

Panelled joinery, similar to what's in the kitchen, appears again in the master bedroom upstairs, but this time in a whitish colour.

At this level of the apartment, there is also an almost-black sauna room that's fronted by a panel of glazing, providing views out across the beachy landscape.

This is the first collaborative interiors project from Van Der Linden and Geldof, who are based respectively Ghent and Antwerp.

Other striking Belgian homes include Apartment A by Atelier Dialect, which boasts a mint-green bathroom, and the Spinmolenplein penthouse by architect Jürgen Vandewalle, which is simply arranged around three blocks of furniture.

Photography is by Piet-Albert Goethals.