Wow haus: NOWlab's split-level Kreuzberg pile

Jörg Petri and Daniel Büning's Berlin-based NOWlab studio is no stranger to experimentation and outside-the-box design (see their recent glacier-inspired biodegradable furniture), but their new architectural venture fulfils the 'WOW' principle of their remit with particular aplomb. 

The interdisciplinary practice's Haus JJ – located on the fourth and fifth floors of a terraced pile in the central Berlin district of Kreuzberg – is a two floor, modernist family home arranged around a central 'pivot point' hall that connects the levels by way of a spiral staircase. 

It's not a hugely expansive space, but the the delineation of the floors as private (the fourth, comprising bedrooms and study areas) and public (the fifth, housing an open-plan kitchen/lounge/dining area, a clean slatted partition wall and access to a terrace) brings cohesion to the apartment. 

So far, so pleasantly conventional, but Haus JJ's real draw comes with the more nuanced aesthetic and functional elements of NOWlab's design. The inclusion of a sliding door to open the workspace up to the hall allows for a degree of modular customisation, and the wood-clad spiral staircase (the rope bannister is a neat detail) was always going to be a crowdpleaser; but it's the subtle touches of a colourful, organic floor design inspired by the sprawling growth of the wine plant on the building's exterior wall and the consistent, curved rhomboid form of the stairwell and skylight above that show real design nous. 

Best of all is the resolutely child-unfriendly sliding pole that connects the fifth-floor's 'secret room' and the fourth's work space. 'The fire pole creates  an efficient and easy-to-use circulation loop between the two,' NOWlab explains; a (one assumes) puckish statement that exemplifies Petri and Büning's charming – and, at times, irreverent – design approach.