How to build the world's most beautiful staircase

Any follower of our social media channels will know how passionate we remain about the staircase that we designed a few years ago with Webb Yates Engineers and which was so expertly constructed by The Stonemasonry Company at our award-winning Camp End Manor project, itself designed by our founder, John Lees.

What we are talking about is the world’s first solid stone* floating 270º helical staircase. By that we mean a stone staircase constructed in the traditional manner of a cantilevered staircase but, and here’s the mind-blower, without a supporting wall. Yes, literally floating!

* OK, there might be a bit of steel cable hidden in there too.

So, how was it done? We asked stair-magician and engineer, Steve Webb, to reveal the secrets behind its incredible design:

“The stair at Camp End Manor is formed of a number of stone blocks, each one forming a tread. Each of these incorporate drilled holes through which pass steel cable tendons. The tendons are stressed by a hydraulic jack, pulling the stone blocks into compression.

“Normal structural sections work by one face (the bottom face in a simple beam) taking tension and the other, compression. The reason that stone (or more usually concrete) needs to be reinforced is because the tension capacity of these brittle materials is not very high. When ordinary reinforced sections are used, the reinforcement bar stretches and the concrete cracks, significantly reducing the stiffness of the beam. Pre-tensioning a section means that all of the material is forced to stay in compression even as the beam flexes. There is a simply a gradient between very low compression at the bottom face and high tension at the top face. This, therefore, never cracks and is far stiffer in use. 

“Post-tensioned concrete is a common and very effective structural form, but concrete suffers from long term creep deformations. This means that under a given load the concrete continues to deflect for a long time. This long term movement is caused by water, trapped in the concrete when it is cast, slowly working its way out of the concrete when it is compressed. This causes progressive movements in concrete structures that can only be countered by making concrete sections deeper. Stone though does not suffer from this effect. Stone is roughly twice as stiff as concrete in respect of long term movements because of this.

“These measures, using stone and post-tensioning, mean that stone sections formed in this way can be approximately half the depth of their equivalent in concrete. It is also true that the carbon footprint of stone is roughly 1/0th that of concrete, so an environmental benefit as well.

“The analysis of the stair is complex. The image above shows the solid finite element model used to assess the performance of the stone. This analysis determines the compressions, tensions and movements in the stone, and calculates the amount of pre-stressing that the cable requires to hold the stones together.”

We think you will agree with us, the completed stair is truly spectacular and huge credit goes to our client, Werner Capital for putting their trust in the design team to use such pioneering technology for the centrepiece of their project.