Aluk completes tallest tower
The 110m, 29-storey Westmark Tower was the tallest residential tower completed in central London during 2021.
Part of Berkeley Homes Central London’s prestigious West End Gate development in Marylebone, it features more than 14,000m2 of unitised curtain wall, designed and supplied by AluK and installed by envelope contractor, Martifer.
According to Aluk, a stand-out feature of the project was the collaborative approach demonstrated by Aluk and other consultants from the outset, which is said to have effectively de-risked the process for both the client and the contractor at pre-tender stage.
Aluk worked with the lead architect Squire & Partners, delivery architect Design Delivery Unit (DDU), facade consultants Cladtech Associates and structural engineers WSP on a RIBA 4 system design for the unitised envelope.
Steven Watkins, Aluk’s head of projects, explained: “Aluk’s specialist expertise meant that we could create a unitised facade solution for the post-tensioned concrete frame which easily satisfied the design intent, while making sensible savings on metal and accessory costs.
“As well as accelerating the design of the structural frame, this approach saved Berkeley many months compared to the normal procurement route and meant that the tender returns for the fabrication and installation of the facade were accurate and comparable. It saved the tenderers the normal costs associated with a bid and ensured that all the commercial and design iteration took place pre-bid and was not left to interpretation.”
The challenge for Aluk was to work with DDU to deliver a design that was true to the architect’s original intent, whilst addressing the technical issues of a curved on plan façade from the second to 29th floor. All the united cells needed to be dead loaded back to a post tensioned concrete frame with a three dimensional floor bracket, whilst catering for the varying facets of the facade.
The final unitised solution features more than 2,200 unitised cells of three principal configurations. Each floor comprises: a vision cell, typically housing Aluk’s concealed vent and full height glass panes, a panel cell, specifically designed to house specialist internal framework to carry articulated GRC (Glass Reinforced Concrete) feature piers and spandrels, and a recessed balcony cell with an integrated floating glass balustrade.
With 36 different angles to overcome in a faceted design ranging from 0° to 15°, Aluk developed a series of common aluminium extrusions to close the joints and reduce the number of profiles required. The horizontal stack joint uses an aluminium profile to carry the gasket and avoid the incidence of crimping as the cells are stacked around the building structure. What is also significant is that every cell connection provides four lines of system seal to ensure that the facade meets the stringent Cladtech performance specification and the CWCT Sequence B test.
The facade design meets the thermal efficiency requirements of the building at 0.95W/m2K, as a weighted average. Using a 43dB Rw(+Ctr) acoustic glass, it also meets the sound reduction targets.