Outdoor spiral staircases: how to choose the right solution

Connecting two levels outdoors requires a staircase capable of withstanding rain, frost and temperature swings without losing stability or aesthetics. The outdoor spiral staircase meets this need well: the vertical development around a central pole reduces the floor footprint and fits discreetly into gardens, terraces and secondary accesses, where space is often the main constraint. Choosing the right spiral staircase means considering three concrete factors: diameter, material and context of use, in order to understand how each affects climbing comfort and integration with the architecture. In this guide we walk you through the choice step by step.

Contents

• Why choose a spiral staircase for outdoor spaces
• Diameters: how to choose between 120, 140 and 160 cm
• Galvanised steel: the material that makes the difference outdoors
• Contexts of use: garden, terrace, independent entrance, accessible rooftop
• Dimensions and connection to the upper floor
• Our outdoor solutions
• Frequently asked questions

Why choose a spiral staircase for outdoor spaces

Outdoors, a spiral staircase takes up little room and wraps around itself, leaving the rest of the space free. It is the solution we recommend when two levels need to be connected but the available ground area is limited, as happens on a terrace, in a courtyard or in front of a raised entrance. The main advantages:

• Reduced floor footprint: the development around the central pole concentrates the climb within a confined area, freeing the surrounding space.
• Discreet insertion: the compact shape integrates into gardens, terraces and secondary accesses without weighing down the environment.
• Flexible assembly: the clockwise or anti-clockwise climbing direction allows the staircase to be adapted to the layout of the space.
• Safety when climbing: anti-slip treads and railing with closely spaced balusters, less than 10 cm apart.
• Adaptability to floor-to-floor height: the number of treads is adjusted according to the height to be connected.

Diameters: how to choose between 120, 140 and 160 cm

The diameter is the first decision to make, because it determines both the space occupied and the climbing comfort. Our outdoor spiral staircases are available in three diameters:

• 120 cm: the most compact solution, suited to small terraces and balconies or to a secondary access where the footprint needs to be kept to a minimum.
• 140 cm: an intermediate diameter, with a wider tread while maintaining a measured footprint.
• 160 cm: the largest diameter, with the most generous tread in the range, recommended when space allows and for frequently used access.

Galvanised steel: the material that makes the difference outdoors

For a staircase exposed to the elements, the material is not an aesthetic detail but a matter of durability. Galvanised steel, obtained by immersing steel in a bath of molten zinc, protects the structure from corrosion and makes it suited to withstanding rain, frost, humidity and temperature swings.

On the treads, the galvanisation is combined with an anti-slip surface that ensures safety even in the presence of rain or moisture. It should be noted that galvanisation provides the best protection against corrosion, and that any slight surface irregularities are the natural consequence of this treatment, not a defect.

For those also looking for a more refined aesthetic result, the galvanised steel can be completed with a powder coating, available in white: a double finish that keeps the protective properties of the galvanisation intact while adding the possibility of harmonising the staircase with the facade and the style of the building. Additionally, painting in a custom colour can be requested by specifying the chosen RAL code.

Contexts of use: garden, terrace, independent entrance, accessible rooftop

Every outdoor space presents different requirements. Here is how to guide your choice according to the context.

• Garden spiral staircase: in a garden the priority is usually to connect two levels without sacrificing the surrounding greenery. A contained diameter and a compact structure allow the staircase to be installed even in small spaces, while the resistance of galvanised steel makes it suited to continuous exposure to the elements.
• Terrace spiral staircase: on a terrace space is often precious and the staircase must integrate with the outdoor furnishings. Here the 120 cm diameter is the one that minimises the footprint, while the painted version helps coordinate the staircase with the flooring and furnishings.
• Independent entrance: to provide autonomous access to a raised floor or a separate dwelling unit, the spiral staircase offers a secure connection with a clean appearance. The railing with closely spaced balusters, less than 10 cm apart, contributes to the safety of the access.
• Access to an accessible rooftop: when the staircase is needed to reach a flat roof or an accessible rooftop, the way it arrives at the upper level becomes important: the arrival system adapts both to an opening in the slab and to a direct arrival, as we will see shortly.

Dimensions and connection to the upper floor

Before choosing the configuration, two aspects of the project need to be verified: the height to be covered, which determines the number of treads, and the way the staircase connects to the upper floor. Let's look at them in detail.

Floor-to-floor height and number of treads

The same staircase can connect different heights thanks to the rise adjustment system, which allows the floor-to-floor height to be reached by adding or removing treads. This way you find the right balance between climbing comfort and overall footprint.
As a guide, the base configuration with 10 treads covers a floor-to-floor height between 210 and 230 cm, while with 16 treads it reaches up to 368 cm. The height should be measured from the finished floor of the lower level to the finished floor of the upper level, slab included. For greater heights, additional treads can be added.

Opening and arrival at the slab

The connection to the upper floor is made via a universal landing with a 60° opening, which adapts to every type of opening during assembly. The staircase can arrive at a square opening in the slab or directly at the slab itself.

For sizing the opening the rule is simple: the opening dimension corresponds to the staircase diameter plus 5 cm. Another useful element during the design phase is the flexibility of the climbing direction: the staircase can be assembled indifferently in a clockwise or anti-clockwise direction, so as to adapt to the layout of the space.

Our outdoor solutions

For outdoor spaces we offer Exterior Zink, the galvanised steel spiral staircase designed to last over time even in the most demanding weather conditions. It is available in three diameters of 120, 140 and 160 cm, mountable clockwise or anti-clockwise, with anti-slip hot-dip galvanised steel treads, plastic handrail and baluster railing.

Those who want a different finish can opt for the galvanised and white-painted steel version, which combines the protection of galvanisation with a more refined aesthetic result.

Learn more on the page dedicated to Exterior Zink White.

Frequently asked questions

Can the outdoor spiral staircase be assembled clockwise and anti-clockwise? Yes. The Exterior Zink kits can be assembled indifferently clockwise or anti-clockwise, so as to adapt to the layout of the space.

What diameters are available? Three: 120, 140 and 160 cm. The smallest diameter is the most compact, the largest offers the most comfortable climb.

How large must the opening be? The opening dimension corresponds to the staircase diameter plus 5 cm.

What height can it reach? The configuration with 16 treads reaches a floor-to-floor height of up to 368 cm. For greater heights, additional treads can be added.

Conclusions

The choice of an outdoor spiral staircase depends on a few fundamental elements: the available space, the frequency of use, the height to be connected and the level of weather protection required. Carefully evaluating diameter, configuration and finish allows you to identify a functional, safe solution in harmony with the building's architecture.

The Exterior Zink staircases are designed to guarantee reliability and durability over time thanks to the galvanised steel structure and anti-slip treads. You can choose between the galvanised steel version, ideal for those who prioritise maximum resistance to the elements, and the galvanised and white-painted steel version, which adds a more refined aesthetic finish while maintaining the advantages of galvanisation.

To explore the features of both versions and identify the configuration best suited to your outdoor spaces, visit the pages dedicated to Exterior Zink and Exterior Zink White or contact our team for support in choosing.