Nights can be long and dark in northern cities like Oslo. But the lack of natural light in this 400 sq m penthouse isn’t really a problem. A 360-degree aspect onto the city and a carefully planned internal arrangement ensure the space makes the most of whatever daylight there is, while the interior’s bright materials defy any gloom.

This apartment, located in the city centre, initially consisted of three smaller units, but now comfortably spreads out to cover the whole floor. Norwegian-born architects Stian Schjelderup and Øystein Trondahl of local practice Schjelderup Trondahl were called in to turn the fragmented space into a fluid, continuous, open-plan layout, created in a subtle style with minimalist details.

The entrance halls features a composition by Norwegian artist Bjørn Ransve

A composition by Norwegian-born artist Bjørn Ransve hangs in the entrance hall of this Oslo penthouse, by local architecture practice Schjelderup Trondahl. Photography: Jonas Adolfsen

In fact, it’s those details, striking in their quality and refinement, that sum up the project’s identity. Of course, it helps to have a generous and trusting client. The owner, a broker who lives here for specific stretches of time in the year with his family, gave carte blanche to the architects despite the project’s heavy technical demands.

All the elements that couldn’t be removed, such as the penthouse’s basic service areas, sit within a hub at the centre of the apartment, surrounded by a large living, dining and kitchen area. A Bulthaup kitchen island is placed within it, featuring custom-made, side-lit walls, while the spartan furnishings around it let the interior’s sophisticated timber detailing shine. Elegant simplicity was key for the architects. ‘It was a great challenge to conceal all the ventilation piping and other necessities while at the same time maintaining state-of-the-art craftsmanship and the simplicity of the atmosphere,’ says Schjelderup.

Oregon pine built-in closet doors with copper door handles

Oregon pine built-in closer doors, with custom-made door handles of copper, in a pattern drawn by artist and architect Katrine Skavlan. Photography: Jonas Adolfsen

White oiled Dinesen Douglas fir planks of up to 15m in length cover the impressive 25m-long living room. The same material has been used to clad walls and for the bespoke doors. Furniture includes both new and rare vintage pieces such as the ‘PP124’ rocking chair or, in the dining room, ten hand-picked, first-production versions of the model known as ‘The Chair’, all by the Danish-born designer Hans Wegner (and produced by PP Møbler). New furniture was custom-built in light-coloured wood. The Nordic identity was very important in the project and also manifests itself in the owner’s substantial art collection that’s a mix of pieces by Scandinavian, mainly Norwegian, artists – Per Kirkeby, Dag Alveng, Bjørn Ransve, Kai Fjell – and international big names such as Warhol.

It was essential that the interiors appeared clutter-free, so storage and technical infrastructure are all hidden within the building elements, behind oak baluster panelling and soft curved walls. The technical equipment and any of its visible elements were tailormade to blend in with the scheme. Similar woods were used throughout to maintain the penthouse’s seamless aesthetic.

Douglas fir and walnut interiors

Recessed sockets and a mixture of woods, such as Douglas fir and walnut, create a seamless aesthetic across the penthouse, achieved through close collaboration between architects and craftsmen. Photography: Jonas Adolfsen

‘It was pretty difficult combining the custom-made furniture from one producer to match with the work of the carpenters, but I am very happy with the result – it was perfect,’ explains Schjelderup. ‘This is only possible with painstaking planning, maximum trust from the client and engaging passionate craftsmen that think like us. You have to be good at interdisciplinary communication and coordination.’ The recessed sockets, cleverly integrated in the floorboards, are an example of the lengths the team went to, in order to retain the clarity of the space.

The specially made entrance door is one of the penthouse’s key features, made out of water jet-cut, perforated sheets of copper, which create the weight and presence of a classical door but with a contemporary twist. The same pattern has been used for the walnut cupboards in the dining area and the wardrobe units. The perforated copper also covers the air vents, which, the architects reveal, was an especially tricky and costly exercise. The pattern was drawn by artist and architect Katrine Skavlan, an employee at Schjelderup Trondahl. ‘It’s one of those projects where all the artisans complement each other and that results in unique detailing and architectural solutions,’ says Schjelderup.

A bespoke walnut cupboard

A walnut cupboard, in the dining area, is cut in a bespoke pattern, also used for copper door-handle details. Photography: Jonas Adolfsen

The master bedroom and three similar but smaller rooms for the couple’s children and guests are separated by a corridor from the open-plan living areas. The bathrooms are minimalist with platinum or white glazed circular tiles and Boffi sanitaryware. LED-lit ceilings are made of a translucent vinyl sheet that gives a soft glow.

Three terraces facing south and east flank the penthouse, and in addition there’s a large 140 sq m garden roof terrace, which offers a citywide panorama, right through to Oslo’s great ford beyond. The plants are in place, but it’ll be a couple of years before the garden grows into full bloom. The penthouse, however, is already a warm family home that balances a contemporary Nordic sensibility with traditional craft.

As originally featured in the May 2014 issue of Wallpaper* (W*182)