From Concept to Centrepiece: Structural Design for Feature Staircases

Floating Cantilever Stair with Glass Balustrade

The Challenge of Making a Staircase That Inspires and Performs

Consider this: a client sees a sleek, floating staircase in a magazine with minimal treads, no visible support, and flooded with natural light. Inspired, they request something similar for a new office reception or high-end residential project. The concept is striking, but beneath the surface lies a critical challenge. How do you preserve that aesthetic ambition while ensuring the structure is safe, stable and code compliant?

This is where structural engineering becomes essential. Feature staircases are not only a visual statement, they are structural elements that must perform reliably under load, across materials and geometry, in settings where performance cannot be compromised.

What Is a Feature Staircase?

A feature staircase is designed to stand out as a focal point within a space. It may be the first thing someone sees when entering a building – whether a commercial atrium, a boutique hotel lobby, or a luxury home. These stairs go beyond utility. They contribute to architectural identity.

Common feature staircase styles include:

• Cantilevered or ‘floating’ stairs with open risers

• Spine beam or mono-stringer stairs

• Spiral or helical stairs

• Monumental, multi-flight centrepiece stairs

Steel is typically the backbone of modern feature stairs, valued for its strength-to-size ratio and versatility. However, feature stairs often combine materials, such as steel for structure, timber for warmth, glass for transparency, and concrete for weight and impact. The image below is an excellent demonstration of this, which showcases the architectural vision of the Kings Cross R8 Project, underpinned by our structural design.

Kings Cross R8 - Feature Stair Design

Structural Engineering Considerations

The success of any feature stair hinges on early structural input. These staircases introduce complex loading, support and performance considerations:

• Load paths: Feature stairs often impose concentrated or asymmetric loads. A cantilevered stair must transfer large bending forces into the floor or wall. Spiral and helical stairs introduce torsion and uplift.

• Deflection and vibration: Users expect feature stairs to feel solid underfoot. Lightweight or long-span staircases can be prone to flex or bounce. Finite Element Analysis (FEA) and dynamic modelling help optimise design to control movement.

• Support interfaces: Fixing into slabs, walls or beams may require local strengthening. In refurbishment projects, this can impact ceiling voids or finishes. Engineers assess structural capacity and coordinate required modifications early.

• Coordination with building layout: Feature stairs often require large voids and clean interfaces. The structure must be aligned with architectural vision from concept stage.

In house nonlinear deflection analysis of cantilever steel stair

Material Behaviour and Design Detail

Steel is the material of choice for feature staircases, thanks to its ability to deliver slender elements with significant strength. It is well suited to long cantilevers, tight spirals and sculptural stringers. Plate steel can be folded, welded or laser-cut to create monolithic forms or delicate supports.

Timber, concrete and glass are commonly used in combination:

• Timber treads or cladding add warmth, but usually require hidden steel support

• Glass balustrades enhance openness but must meet loading criteria for crowd or public use

• Concrete works well in curved or monumental forms, but introduces dead load and construction challenges

Invisible support is often a hallmark of good structural design. Hidden brackets, stiffeners, or steel frames embedded in walls can deliver minimalist appearances while providing the necessary strength.

UK Regulations and Safety Compliance

Despite their sculptural appeal, feature stairs must fully comply with UK Building Regulations. Key standards include:

• Approved Document K: sets rules for rise, going, pitch, handrails and guarding. It ensures stairs are safe and accessible.

• Approved Document M: applicable to public buildings, requires stairs to be inclusive and usable by all.

• BS 5395-2: specific to spiral and helical stairs, governing geometry and loading.

A common issue is the 100 mm rule – open risers must be designed so that a 100 mm sphere cannot pass through. This protects children from falling or becoming trapped. Homeowners and designers often overlook this constraint when selecting minimalist staircases.

Feature stairs in commercial or multi-storey environments may not form part of protected fire escape routes. This affects their location, enclosure and material choices. Structural and fire engineers must work together to ensure the open stair does not compromise building safety.

Common Client Misunderstandings and Pain Points

Clients are often surprised by the complexity of bringing a feature staircase to life:

• “Can’t it just float?” Aesthetically, yes. Structurally, only if supported correctly. Cantilevered stairs require stiffened walls, strong floors or hidden frames. In existing buildings, this may involve significant intervention.

• “Why does it cost more?” Feature stairs are bespoke, engineered structures. They are often prefabricated, tested and installed with precision. Materials, hidden supports, and compliance checks add cost.

• “Why doesn’t it meet code?” Open risers, lack of handrails, or steep pitches might look clean but often fall short of Approved Document K. These issues can be resolved with clever detailing if addressed early.

Clear communication and early involvement of the structural engineer help manage expectations, reduce redesigns and achieve a high-quality outcome.

Shepherd Gilmour’s Role

At Shepherd Gilmour, we specialise in the structural design of bespoke staircases. We understand the architectural ambition and match it with technical excellence.

Our portfolio includes complex staircase designs at King’s Cross R8, where we engineered three unique stairs: a cantilevering steel stair with glass balustrade, a long-span steel stair clad in timber, and a full-depth steel plate stair as a dramatic centrepiece.

We routinely use FEA to assess vibration, deflection and fixity. Our designs consider installation sequence, construction tolerances and material integration. By collaborating closely with architects and fabricators, we ensure the final stair meets performance and aesthetic requirements.

Conclusion: Delivering Design Without Compromise

Feature staircases represent the meeting point of architecture and engineering. Their success depends on achieving visual lightness with structural rigour, all while complying with safety standards.

With early engagement and thoughtful design, structural engineers help deliver the dramatic staircase that inspires confidence – one that looks as effortless as it is robust.

Whether it is a floating stair for a boutique workspace or a helical stair for a luxury home, the key to success lies in collaboration and expertise.

Contact Shepherd Gilmour today to discuss your feature staircase project, we'd love to hear from you!