Floating Stair: structural details and ideas

Cantilever stairs, also known as suspended stairs, are one of the most fascinating design innovations in the world of architecture and interior design. But how do they work? How are they designed? To design a cantilever stair, carefully evaluate its aesthetic impact and calculate the structure in compliance with technical construction standards; a BIM architectural modeling software can be of great help. Below I propose a series of renders of cantilever stairs created with BIM software. You can freely draw inspiration from these images for your project!

What is a Floating Staircase?

Cantilever stairs are a technological solution that combines functionality and design.

Traditionally, a stair consists of risers and treads: the tread of a traditional stair is the horizontal part you walk on, while the riser is the vertical part that connects one stair to another. Cantilever stairs forgo the riser, making the steps appear as if they are suspended in space and giving the entire stair a more open look.

Supported by a central beam or with steps anchored directly to the wall or another vertical surface, these stairs are designed to conceal the supporting structure and to give the impression that the steps “float” in space, offering a modern and clean look.

Although one might think they are more suited to a minimalist and contemporary design, with the right choice of shapes and materials, they can easily adapt to more classic environments and even to historic buildings of significant architectural value.

They can be installed indoors or outdoors, for businesses, homes, or renovations, and can be paired with various types of railings and handrails, often made of glass or in the form of cables or bars.

Floating Staircase Project | Render created with Edificius

In addition to the aesthetic impact, cantilever stairs are also a refined example of structural engineering, using advanced materials and construction techniques to ensure stability and safety. Let’s see how a cantilever staircase works.

How does a cantilever staircase work?

The charm of a cantilever staircase largely derives from its seemingly impossible design that appears to defy the laws of gravity. But how can such a lightweight structure without a central support remain stable and safe? How to build a cantilever staircase?

The answer lies in precise engineering and material selection. Generally, the steps of cantilever stairs are securely anchored to the wall through pins or other forms of fastening, evenly distributing the load. This arrangement allows for optimal use of the properties of materials such as steel or reinforced concrete, ensuring that the staircase is as stable as it is elegant. The use of structural calculation software is necessary to predict and mitigate any potential issues, ensuring a construction that is not only visually impressive but also safe for users and compliant with building technical standards.

Here’s how a cantilever staircase works:

• anchoring to the wall: the top part of the cantilever staircase is securely fixed to a wall or a load-bearing structure using brackets or robust structural anchors. This anchoring is essential for the stability and safety of the staircase;
• steps: the steps of a cantilever staircase can vary in material and shape, but they are generally made of wood, metal, or glass. These steps are anchored to the top of the staircase structure and extend outward, creating the passages for going up or down;
• tension and compression: the main force that allows a cantilever staircase to function is the distribution of tension and compression between the wall and the steps. The top of the staircase transmits compression to the wall, while the steps resist tension. This distribution of forces is why a cantilever staircase can remain stable without vertical supports;
• balancing: the geometry of the cantilever staircase is designed so that the weight of the user going up or down is evenly distributed across the steps and the supporting structure. This balance helps to avoid sagging or failure of the staircase;
• aesthetic design: cantilever stairs are often appreciated for their aesthetic and modern design. They can add a touch of elegance and minimalism to the interiors of buildings;
• safety: despite their fascinating appearance, it is essential that cantilever stairs are designed and built following strict safety standards. They must be made with robust materials, reliable structural anchors, and carefully calculated design to ensure user safety.

Render Floating Staircase created with Edificius

Floating Stair: structural details

To design a cantilever staircase, it is essential to know and foresee a series of structural details necessary to make the staircase stable and safe.

Load Capacity

To design a structurally sound cantilever staircase, it is necessary to consider the load capacity of its structure. The structure must be able to support not only its own weight but also the weight of any person or object that will use it.

In designing the staircase, it will therefore be necessary to consider the maximum expected load, including elements such as the weight of the steps, the number of people using the staircase, and any additional load such as furniture or large objects.

Structural Supports

Although the steps of a cantilever staircase seem to float, there is always a structural support holding everything up. This can be:

• a load-bearing wall, made of reinforced concrete or solid bricks, for example. In this case, the steps are anchored directly to the load-bearing wall, and there are no particular structural issues. They are supported, for example, by a beam embedded in the wall or fixed directly and individually using chemical anchor bolts and stainless steel spacers between the wall and the step;
• stainless steel frames embedded in a non-load-bearing partition. Each step is supported by a structural frame and can be stiffened by the insertion of glass railings or stainless steel brackets attached to the ceiling;
• a girder positioned under the steps, anchored to the floor and to the landing step. It acts as the backbone for the entire system and is bolted to each step.

Structural Materials

The materials used for designing the treads and the structural support systems of a cantilever staircase influence the strength and stability of the staircase itself.

If lightweight materials such as steel and aluminum are used, the staircase will have a reduced self-weight, while a material like concrete or stone has greater density and therefore more weight; reinforced concrete stairs for example provide greater support to the structure.

While it is crucial to carefully consider the selection of materials based on the specific needs of the project, solid wood is often used, such as beech, oak, or walnut, with thicknesses ranging from 80 to 100 mm to create the steps. Alternatively, resin and Corian are gaining popularity as materials for the steps. Railings can be made of various materials, including glass panels fixed to the sides of the steps or stainless steel. Fastening options vary from visible stainless steel bolts to wooden caps that hide the screws.

Connections

The analysis of connections is essential to ensure that the cantilever staircase is structurally sound. This includes not only the connections between the steps and the risers but also the connections between the structural support system and the steps and risers, which are often just brackets for the cantilever steps anchored in the wall. When designing the staircase, it is important to:

• carefully consider the transfer and distribution of load in these connections;
• ensure that they are designed to withstand the expected loads.

The various types of cantilever stairs

Cantilever stairs can be made in various styles and materials and with various construction techniques to suit architectural needs and design preferences. Here are some of the most common types of cantilever stairs that can be made:

• cantilever staircase on a load-bearing wall – when the staircase runs alongside a load-bearing wall, creating cantilever steps becomes a choice without significant structural issues. A common solution is to create a load-bearing steel element (called a beam) to be embedded in the load-bearing masonry, which serves as the main support for the steps and railing. This solution creates an extraordinary visual effect, with the steps appearing to emerge from the wall in an seemingly suspended manner. Usually, the steps are made of wood (beech, oak, walnut, or other fine woods) without risers. To achieve an extraordinary visual impact, this option can be combined with a glass railing, whose panels are fixed to the sides of the steps. These fixings can be made with visible stainless steel bolts or with wooden cover caps to hide the screws. An alternative could be the use of an external wooden beam;
• cantilever staircase on non-load-bearing walls – when there is no load-bearing wall next to the staircase but rather elements such as posts, partitions, or retaining walls, it is not possible to use a traditional cantilever staircase. In these cases, our designers can develop customized solutions after conducting a site visit and analyzing all project details. One solution could be the insertion of a special cantilever steel element with fastening points to the floor and ceiling. This solution requires the use of intermediate posts, and the cantilever element will resemble more of a steel frame structure than a beam. After the installation of this steel structure, the wall can be covered with drywall or other materials to hide the structure;
• cantilever staircase with a central column – when the structure of the building does not allow for the installation of a traditional cantilever staircase, an alternative solution is represented by suspended stairs with a central column. This column acts as the backbone and supports the weight of the staircase, ensuring maximum safety during use. The central column can be designed in a minimalist style or in a more robust style, depending on aesthetic preferences;
• cantilever staircase with structural glass walls – in some projects, it may not be possible to position the staircase next to a wall. This scenario occurs, for example, when the staircase is placed in the center of a room, atrium, or lobby in a prestigious building or hotel. In these cases, structural glass walls can be used to support the entire structure of the cantilever staircase. The glass walls are usually positioned on both sides of the staircase and are designed to support the load of each individual step. The steps can be made of wood to harmonize with the floor or other surrounding furnishings, or in tempered laminated glass, giving an exclusive touch of lightness and elegance to the entire interior design. The glass walls are specially designed to bear the load of the staircase and are fixed to the floor and/or ceiling. The steps are securely anchored to the glass walls using specially designed stainless steel bolts to ensure a safe and durable structure.

Render Floating Staircases created with BIM architecture software

In addition to these more common types, it is possible to design cantilevered stairs with just treads, with treads and risers, spiral, L-shaped, linear, etc.

Floating Staircase: design ideas

Cantilevered stairs, with their light and floating structure, have always been subject to design innovations.

The possibility of bringing more light to spaces with open treads through which it filters allows for the creation of plays of light and shadow that enrich the architecture of a residence, a commercial space, or an exhibition area.

The type of finish of the treads themselves, the chosen material, and even the coloring (in addition to additional details such as integrated LED lights or steel profiles) give great impact to the staircase, providing:

• greater solemnity when using wooden materials or natural stone cladding for the treads;
• greater innovation and practicality with Solid Surface materials;
• greater transparency by using glass surfaces.

Here are some innovative cantilevered stairs that have been trending in recent years.

Curved Floating Staircase

A curved cantilevered staircase has always been synonymous with class: a common object like a staircase becomes extraordinary thanks to the use of sinuous shapes and special finishes that make it a true design object.

A spiral cantilevered staircase, supported by central or lateral beams and enriched with curved glass or steel railings, when positioned in the center of a room, divides and defines the spaces and becomes the focal point of the entire environment.

Floating Glass Staircase

A glass cantilevered staircase has both the treads and the railing/support beam made of glass. The only stainless steel elements are the anchoring points between the tread and the wall or glass railing.

Glass cantilevered stairs are an essential proposal, as they allow for connecting levels without inserting elements that weigh down or hide portions of the environment being designed.

Fully glass stairs can be straight or can adapt to any environment and structural premise. The transparency gives visual impact to the staircase, an impact that increases with the addition of monochromatic or polychromatic LED lighting for the treads or structures.

Floating Stair Brackets and Stringers

Among the various innovative versions of cantilevered stairs, we find:

• those with zigzag beams, often in steel, which give the staircase an elegant and modern appearance. Leaving the beams a different color from the treads or perhaps in exposed steel provides contrast and highlights the structure;
• those with treads supported by steel cables anchored to the ceiling, which allow more light to flow into the room;
• those multi-level where even the landing is cantilevered and the handrail, which perfectly follows the shape of the staircase and develops ergonomically, collaborates for specific safety functionalities based on needs.

If you are modeling the cantilevered staircase of an apartment and want to see which materials and technical solutions create a more innovative work, my advice is to create a series of real-time renderings.

Advantages of BIM software for designing a cantilevered staircase

The adoption of BIM modeling software in the design of cantilevered stairs offers numerous advantages that go beyond simple graphic representation. Here are some of the main strengths:

• choice of the most appropriate type
  The flexibility of a BIM environment allows for exploring different types of cantilevered stairs in a much shorter time compared to traditional methods. You can quickly modify materials, dimensions, and geometries and see how each variant integrates within the project. This ability to experiment in real-time greatly aids in choosing the most suitable type of staircase for the specific context of the project.
• structural simulation
  One of the main advantages of using BIM in this context is the ability to perform structural simulations. Thanks to integration with structural analysis software, it is possible to analyze the strength and durability of the cantilevered staircase under various conditions. This provides additional assurance regarding the safety of the structure, while also allowing for the optimization of material use.
• visualization and presentation
  The advanced graphic representation and 3D rendering capabilities of BIM software allow for creating extremely realistic visualizations of the project. This is particularly useful when presenting the project to the client or other stakeholders. Being able to show a detailed simulation of the staircase in the context of the entire building can contribute to a more informed and conscious decision by the client.
• consistency and integration of the project
  The BIM environment facilitates project consistency. Any changes made to the staircase model are automatically reflected in all related views and documentation. This reduces the risk of errors and inconsistencies, ensuring that all team members are always updated.
• cost and time optimization
  The efficiency of BIM allows for more accurate planning of costs and timelines. The BIM model can be used for an accurate estimate of materials, labor, and time required, helping to avoid delays and resource waste.

Render Floating Staircase created with BIM architecture software

To deepen your understanding, read also:

• Technical guide to designing a spiral staircase;
• How to design stairs: criteria, regulations, and examples to download.

FAQ on Cantilever Stairs

What is a cantilever stair?

A cantilever stair is a stair without risers, with steps that appear to be suspended in space. It can be supported by a central beam, anchored to the wall or another vertical surface, offering a modern and clean design, but also adaptable to classic or historical contexts.

How does a cantilever stair work?

The cantilever stair is supported by anchoring the steps to the wall or the load-bearing structure, distributing tension and compression between the steps and support, and balancing the weight of the user. The steps can be made of wood, metal, or glass, and the structural design ensures safety and stability.

What structural details are important in a cantilever stair?

Structural details include the load-bearing capacity of the structure, supports (load-bearing walls, steel frames, or beams), materials of the steps and supports (solid wood, metal, glass, concrete), and the connections between steps and structure, designed to withstand the expected loads.

What types of cantilever stairs exist?

The main types are: on load-bearing walls, on non-load-bearing walls, with a central column, with structural glass walls, curved, spiral, L-shaped, or linear. Each type is chosen based on structural and aesthetic needs.

What materials can be used for a cantilever stair?

The steps can be made of solid wood (beech, oak, walnut), tempered laminated glass, metal, concrete, or resin. Railings can be made of glass, stainless steel, or other materials, with visible or hidden fixings, depending on the design.

What design innovations exist for cantilever stairs?

Innovations include open steps for light play, materials like Solid Surface or glass, integrated LED lighting, zigzag steel beams, steps supported by cables, multi-level stairs with ergonomic handrails, curves, spiral designs, or completely transparent for an elegant aesthetic impact.

What advantages does BIM software offer in the design of cantilever stairs?

BIM allows for quick selection of stair type, simulation of structural resistance, creation of realistic renderings, maintaining project consistency and integration, and optimizing time and costs, supporting all phases from design to final presentation.