With a recently purchased top floor of an office building freshly approved for change of use, our client presented us a blank canvas on which to craft a home that reflected their eclectic personality while still having family home potential.

The colossal 364 square metre floor space and 5 metre high vaulted ceilings of this untouched conversion provided a real playground for design encouraged by a client with an appetite for bold creativity.

It was a site as defined by its location as its impressive structure. The relationship with the exterior – high above the streets of Vauxhall with clear views across London and nothing but open sky above – would be essential to the character of the design.

Despite the generous abundance of space to work with, filling that space correctly proved to be a puzzle. The grand, church-like vaulted ceilings were certainly striking but created awkward, triangular angles that limited upwards expansion.

Natural light could also easily be lost in a space so large. With most the sun coming in through roof lights, overcrowding the layout with cellular rooms or splitting it into two levels could result in entire rooms being trapped in darkness.

Then there was the look and feel to consider. Vast, ex-commercial properties can easily end up feeling like galleries rather than a home if the character and texture of the building is plastered and painted over instead of being celebrated and enhanced.

Instead of trying to fit a cramped upper level into the vaulted ceilings, we broke through them: a rectangular block protruding through the roof and suspended above the main floor to create 211 square metre mezzanine housing four bedrooms.

This avoided the sloping headroom of the pointed ceilings without compromising the grand character of the structure. The vast space is also preserved by elevating the second level above the first, creating uninterrupted views from front to back.

Uninterrupted views also mean uninterrupted light, with the sun able to fill the space through the roof lights and the iconic semicircular windows dominating the far end of the main floor. In the upper level, breaking through the roof removed any restrictions on window placement, giving every bedroom ample light.

Only the space below the mezzanine sits in shade, where we placed a cosy sitting area and a walled off gym complete with wash and changing facilities, hidden away for much needed privacy.

The brick and chunky steel girders of the original structure are preserved and complemented by a variety of metallic and stone textures throughout. Polished concrete gives the floor both rugged character and a clean shine, while rougher concretes, gleaming metals and clear glass create defined areas without resorting to walling them off.

Our client's playful character is just as represented in the décor. An indoor garden, complete with a tree (the ideal species chosen by an arboriculturist) is kept healthy with an irrigation system and an opening roof. Even a motorbike, proudly displayed alongside a diverse art collection, manages to fit in.

This design represents the ideal marriage of unshackled creativity from both ourselves and our client, given life by a truly inspiring structure and freedom of space. No one would suspect a home this entertaining was once an office.