Creating Pembridge Villas
We are very excited to be able to unveil to you some beautiful images of our works at Pembridge Villas. At The Stonemasonry Company Limited we are committed to using traditional methods in new ways, and the staircase at Pembridge villas is a great example of what can be achieved with this approach. A few weeks ago we gave you an insight into the design of a cantilever stone staircase, and this time we thought we would give you an insight into how this elegant, two flight, post tensioned stone staircase was created and what challenges came with the unique design, including a complex half landing. Please feel free to browse the beautiful project photos (https://www.thestonemasonrycompany.co.uk/pembridge-villas), we hope that after reading this brief article you will be able to appreciate the work that went into it’s construction in a whole new way.
In line with our client’s brief the staircase had to be free floating, and it had to be solid stone, of course, but a long list of constraints were what shaped the rest of the design. The distinctive leaf shape and half landings were the product of the space available and our engineering considerations. The layout needed to reflect the walls of the stairwell and the start and end could only fall within set spaces. Whilst complying with building regulations the staircase also had to satisfy our criteria for comfortable use, we didn’t want to make any steps feel cramped. At no point could there be less than two meters of head height (a common issue that is often not fully considered before we join a project), in this instance this conflict was caused by the bulkhead above step four on the lower flight. Lastly, there needed to be continuity and a sense of consistency between both flights. After considering all of these requirements, and considering the space, Ergonomics, Engineering and design guidelines, our team introduced Half Landings to the design, thus meeting all of the project requirements without compromise.
To the best of our knowledge a landing had not been incorporated into the middle of a post tensioned stone staircase before, so including one produced a whole new set of challenges, giving us the opportunity to design, develop and test an entirely new set of skills in order to achieve the end result. We concluded that the landings would have to be of bespoke steel construction, firstly in order to connect the cables and secondly to effectively interface with the stone, finally this had to be designed to efficiently transfer the force between the two sets of stairs. It was established that the multiple steel cables used would need to be tensioned in unison to avoid unequal stresses and movement, therefore there needed enough space within the structure to accommodate large pieces of tensioning equipment. All the while, it had to be kept in mind that the half landing would be concealed within a stone exterior, with points made available for the final cladding to be fixed securely.
A common challenge behind our work is that of co-ordination, Pembridge Villa was no different. The stone used was quarried in France as per our exact specification, and then shipped to our Lincolnshire workshop where each step was handcrafted by our experienced team. The steelwork required was fabricated in Cambridgeshire and finally the staircase installed in London. Efficient communication and logistical planning were as vital as ever, and it was through the close relationships we have with our suppliers, hauliers and of course with our London based engineers, Webb Yates Engineers (who were instrumental in the design process), that we were able to effectively and efficiently deliver this unique stone staircase, fitting the stone steps, steel and primary structure together perfectly to make this delicate balance of forces work.
Given that this was a somewhat experimental staircase, and given the logistical and technical considerations we are very proud to have been part of this impressive project. The Stonemasonry Company Limited’s continued commitment to undertaking complex and innovative Post tensioning projects has meant that the expertise of our design, manufacturing and installation teams has continued to grow and we hope that it will continue to do so with every new project we undertake.