Diapo to design cantilever helical staircase

A Diapo product story

Edited by the Interiorstalk editorial team Jan 20, 2010

Diapo has been appointed to design and manufacture an ultra-modern glass and steel cantilever helical staircase that will spiral around a custom-built fish tank.

The house is privately owned by Steve Malcolm and is a GBP9m residential development overlooking Gleneagles' Queen's golf course.

The stairs are fabricated from a single steel helical stringer with cantilevering glass treads and a glass balustrade to the stairs and landing.

At 21,000ft2 (1,950m2), this private home is being built around a GBP1m aquarium, which measures 4m in diameter and rises three storeys through the centre of the property.

The stairs are fabricated from a single steel helical stringer with cantilevering glass treads and a glass balustrade to the stairs and landing.

In terms of the steelwork, the stringer will be connected to the floor structure using a steel base plate and supported off steel CHS columns (columns by others) at three other locations with fabricated brackets.

The stringer will be a customised steel parallel flange channel (PFC) running around the outer edge of the stair, with a plate infill welded into the open side and 'post-box' cut-outs to enable the glass treads to cantilever from the stringer towards the aquarium in the centre.

The glass treads are to be made of wedge-shaped, heat-soaked, toughened, 40mm-thick laminated glass with a structural sentry interlayer.

They will be inserted through the stringer from the outside edge of the staircase and held in place using high modulus silicon and nylon packers.

The landing glass will be supported off the PFC stringer in a similar manner to the treads.

The glass balustrade is to be made of heat-soaked, toughened, 15mm-thick laminated glass clamped between the stringer and a fascia plate.

In terms of structural feasibility, the design loads will be taken as a 1.5kN/m2 floor load for a residential building and a 0.36kN/m run balustrade loading taken in accordance with BS6399:pt 1.

The target frequency of the stairs will be 7Hz with 25 per cent live load taken as participant mass.

This means that the staircase will exhibit mild perceptible vibrations when trafficked energetically, which is normal for a staircase of this type, according to the company.

It is assumed that the supporting structure has been designed with adequate stiffness and strength to support the proposed staircase.

The project is due to be completed by spring 2010.