Client: Stoneforce LTD
Project Duration: October 2016 – March 2018
Location: Cleveland Row, St James’s, London
Surveyor: David Regan
Selwyn House is a large residential building next to St James’s Palace in London. The property was built in 1904 and backs on to the famous Green Park in London. As part of a multi-million-pound development, Selwyn House is undergoing major changes with the addition of a new floor and a multi-storey basement.
THS Concepts was appointed by Stoneforce Ltd to undertake weekly monitoring surveys of the property whilst the construction work was being undertaken. Due to the scale of the works the monitoring scope included other properties in the nearby area. Utilising a cherry picker, we started by fixing our targets to the walls of the properties at various heights to give us the best possible understanding of the potential movement.
Following the initial set-up, our experienced surveyor David Regan returned to the project on a weekly basis to re-survey in the locations of these targets. The survey was undertaken using our Leica TS15 1-second instrument, renown for its high accuracy and reliability. David’s weekly survey and subsequent reports demonstrated the minor movements both vertically and horizontally that naturally occur with this level of construction work. Our weekly movement reports and graphs clearly demonstrated the extent of the movement and how it is looking over time.
The results of the survey were quite interesting to view. Over time a clear trend revealed itself in that the minor movements were contained to Selwyn House only. There was little to no effect on nearby buildings despite the extent of the works such as the basement being built. Another interesting trend was the extent of the movement during the “heavy” construction works. During the digging and extensive structural works, the points were subject to small movements. Once this ended, however, the point movement slowed down. This demonstrated nicely how the movement was as a result of the works.
Overall the project went well. If we were to undertake it again we would try to place the targets on the buildings in slightly better positions that would allow us to set up our survey equipment in fewer locations. That would speed up the time on site, allow us to get back to the office quicker and issue the report for that day faster.