May 10, 2019
CCL has been awarded the PTI Award of Merit for its involvement in the refurbishment of two heritage townhouses at 6 and 7 Mount Vernon in Boston, USA. Chief Technical Officer, Carol Hayek from CCL USA accepted the award at the PTI Awards ceremony which took place on 6th May 2019 at the Hyatt Regency in Seattle.
Located in the Beacon Hill conservation area of Boston two prestigious townhouses, 6 and 7 Mount Vernon, were being converted into luxury 21st century properties. Part of the developer’s vision was to create an underground parking garage by excavating beneath the two properties.
The primary challenge for CCL and the project’s developer/contractor, SEA-DAR Construction, was to ensure that the existing property and neighbouring buildings were not damaged by structural movement during or after construction. Further challenges included logistical issues caused by the narrow streets surrounding the site and the need to maintain the building’s exterior aesthetic.
SEA-DAR called upon engineering experts from CCL to devise a top-down post-tensioned (PT) solution to overcome the numerous issues associated with the original steel specification and the logistical implications of installing steelwork.
CCL’s response was to design a PT transfer slab tied into the existing structural walls to support the above ground structure during excavation of the basement and after construction, while at the same time managing structural movement.
Using PT also reduced the number of support columns in the basement from 18 to just two, increasing the amount of usable space, and reduced excavation depth to enable the use of mini piles.
After the award ceremony Carol Hayek commented: ‘We are proud to receive this award for a project that allowed us to demonstrate how PT can be used as an alternative to more conventional construction methods, saving time and cost while reducing complexity and providing significant structural benefits.’
The 25 Beacon project was covered in Structure Magazine in March 2019.