The apartment, which was renovated from top to bottom, occupies a glass pavilion on the roof of a 1930s residential building in the borough of Mitte.
"In this project, our clients gave us a lot of freedom," said Gisbert Pöppler, the studio's eponymous founder. "That, however, does not mean that we imposed our design and taste on them."
"A good design is like a tailor-made suit," he added. "It should fit perfectly without being the centre of attention."
The studio reorganised the floor plan so that the main bedroom, guest bedroom and bathroom are the only areas of the apartment that are completely closed off.
Instead of walls, living spaces are now demarcated by different materials. In the study, surfaces are overlaid with teak while the entryway is panelled in red-lacquered wood.
"The original plan was classic: hallway, room, room, room," Pöppler explained. "We turned it into an open village."
In the kitchen, Gisbert Pöppler collaborated with the clients to design a simple geometric relief wall. This was crafted from a pale grey limestone that the owners sourced during a trip to Verona, Italy.
The space is finished with an olive-green prep counter and mint-coloured cabinetry, both tailor-made to accommodate the owners' selection of pots and pans.
The cane-inlaid storage cupboards that run throughout the apartment are also bespoke.
Inside there are several shoe cubbies and shallow drawers, perfectly sized to hold the client's array of shirts. The interior of the storage unit is lined with orange Formica, as the clients wanted it to be durable and easy to clean.
More unique details appear in the guest bathroom, which features a rounded washbasin made of white-glazed lava stone from Sicily's Mount Etna. In contrast, dark oakwood was used to construct the basin's base.
The bathtub is set inside a deep wall niche clad in South American marble, with a dropped ceiling giving this space a cosier feel.
The ceiling in the living room was also lowered and covered with stainless steel panels.
"One could assume that metal seems cool but it is the contrary," Pöppler said. "The hazy reflections in the steel give the room a sense of height and have a comforting warmth to them."
Bespoke furnishings in the living room include the pentagonal white oak table in the breakfast nook and the formal wooden dining table, which Pöppler says has an "elaborately designed" underside.
"We knew that the owner of the house often lies on the carpet listening to music, so we didn't want him looking at a technical construction," he said.
Gisbert Pöppler isn't the only studio to forgo off-the-shelf furnishings in its projects. Dutch practice i29 recently created a custom storage system for an Amsterdam apartment to accommodate the client's extensive compilation of artworks and books.
And in San Francisco, architect Jamie Bush filled a residence with an eclectic mix of custom furniture and vintage finds to make it look as if the owners had collected the pieces themselves.
The photography is by Robert Rieger.