Spiral staircase: main features, types, its advantages and disadvantages

A spiral staircase is a structure that is built around a central post that acts as an axis for its steps.

The origin of this type of staircase dates back to the Middle Ages. They were used both for aesthetic purposes and for defense (their structure makes it difficult for possible attackers to advance). Today, they can still be seen in castles, fortresses, and churches that have survived over time.

What are the main features of a spiral staircase?

The design of a spiral staircase is very important and must account for several factors so that it isn’t uncomfortable or dangerous. The first things that must be taken into account are the start and end points in order to calculate: the degrees of rotation, the height of the steps, and the surface and shape of each step.

All of the steps in a spiral staircase are shaped like a trapezoid, which means that its outer part is wider, and the area decreases in size as it approaches the center. Whoever ascends or descends a spiral staircase should go along the outer edge, where the steps allow for greater, safer support.

A spiral staircase can be built with a turn to the right or to the left. The line of the stairs usually goes clockwise and typically includes a handrail so that people can support themselves with more safety, especially when descending.

 What types of spiral staircases are there?

The most well-known types of spiral staircases are:

• Closed shaft spiral staircase: a continuous circular structure without an intermediate landing that is joined and fixed to a central axis. 
• Spiral staircase with a vertical axis: in architecture, this type of staircase has a vertical axis or wall supporting the steps. The main feature of this type of staircase is that its steps come out of a spiral without leaving a gap in the axis’s place. 
• Spiral and open staircase: its central axis is open, and it may or may not have a railing. Built around a circular well, with a hollow in the center that resembles an eye. 

What is the difference between a spiral staircase and a helical staircase?

While both types of stairs share the characteristic of being the opposite of a traditional staircase, they also have the following differences:

• The structure of a spiral staircase is curved and revolves around a straight column which acts as a central axis, while a helical staircase doesn’t need a central post, so it may vary in shape and structure thanks to the curved axis that accompanies the positioning of the steps. 
• Spiral staircases take up less space than helical ones, and they are ideal for small spaces. However, they are usually narrower, and they can be uncomfortable for some. Helical staircases require more space to be set up, so they are more comfortable to use. 

What are the main advantages and disadvantages of a spiral staircase?

The main benefit of a spiral staircase is optimizing space, as it needs a small footprint and occupies a very small area in all compared to other types of stairs.

Generally, a spiral staircase only lets one person ascend or descend at a time. If two or more people are going up or down, they must go in the same direction and in single file, not next to each other, as they could on a conventional staircase. For this reason, spiral staircases are not viable in high-traffic areas.

Since it curls back on itself, a spiral staircase puts a height limit on those who use it. This can make it uncomfortable for those of greater stature and make it very difficult, if not impossible, to take bulky objects on them.

Spiral staircases are very versatile. They can be built out of a large number of materials and are perfectly suitable for both interiors and exteriors.