Cantilevered Marble Staircase

The project

A cantilevered marble staircase built into a refurbished house, each tread socketed into a reinforced spine wall so the flight appears to float free of any visible support.

The effort behind it

The wall was designed and built before the stair: 440mm of reinforced blockwork with cast-in pockets set to a 3mm tolerance. Every tread was dry-set, checked with a digital level, then bedded and left propped for seven days. One tread was re-cut after a hairline vein was judged too close to the nosing.

Challenges faced

Working in Knightsbridge, London SW7 brought the classic London constraints: party walls on both sides, no lay-down area, and neighbours two metres from the scaffold line. The Cantilevered Marble Staircase programme had to absorb structural discoveries made only after opening up, and every delay risked cascading into the finishing trades booked behind us. Weekly look-ahead planning and a just-in-time delivery schedule kept the site moving without ever blocking the road.

Team & involvement

Delivery was led by a working site manager with a core crew of our own trades, supported by structural engineers, building control and specialist subcontractors we have worked with for over a decade. Morning briefings, a live programme on the wall and photographic records of every concealed stage meant the client in Knightsbridge, London SW7 always knew exactly where their project stood.

A successful outcome

Cantilevered Marble Staircase was handed over on programme and within the agreed budget, with building control sign-off at the first inspection of every notifiable stage. The client moved back in on the date we gave them at tender — and the aftercare visit twelve months later found nothing to put right. That is the standard every DBS project is measured against.