Trade contractors were selected on a value for money basis, not necessarily lowest price, says Rushworth and they were selected from shortlists of no more than three pre-qualified firms. Contractors were assesed also on how safe their work methods were.
Specialist trade contractors and suppliers were asked for their ideas and advice at every stage, from design to handover.
Standard designs and components were used wherever possible and designs were reviewed with trade contractors to simplify manfuacture, raise productivity and improve quality. For instance the steel structural frame used standard size beams and columns and simple connections designed by the steelwork trade contractor. Sections were interchangeable from floor to floor so one section could be swapped for another, to minimise the effects of any delivery delays.
As much use was made of prefabricated components as possible, to get factory-made quality. Intumescent paint was used for fire protection and applied off site in a safe, controlled factory environment rather than spraying on site, which requires an area to be sheeted off, tying up space.
'The biggest decision was to opt for panelised cladding rather than a traditional stick system,' says Rushworth. 'It is normally much more expensive but we were driven by the tight programme and the lack of lay down areas.' The client also wanted a panelised system for quality reasons. Exterior worked with Foggo and Gartner to bring the price differential down to just 5%. The real win came on erection time. 'A stick system would have taken 16 weeks to put up; Gartners took only five,' says Williams.
Standard fitout products, such as partitions, floors, ceilings and structural cabling were procured from established suppliers which already had long term agreements with Exterior. Sprinkler pipework came prefabricated and the construction manager was particular impressed with a modular wiring system. 'Instead of pulling several cables through fixed trunking, the ready wired, flexible conduits were delivered with the ends already terminated with connection boxes,' Williams explains. 'We'll definitely be using it again.'
The boiler unit was initially designed to go in the basement, but a value engineering exercise led to it being moved to the roof leaving extra space in the basement for an 'executive lounge' at no cost to Mercury/HQ. The boiler plant room was manufactured off site and lifted on to the roof with all the pipework stubs and wiring, ready to be connected.
Delivery was organised on a just in time basis because of the tight footprint of the site and restricted access. And apart from the use of a crane to place the cladding panels the building was constructed from the inside, doing away with the need for scaffolding around the outside of the building. Trade contractors worked off mobile towers on each floor.
Working areas and lay down areas were agreed in advance so that materials were delivered right where they were needed.
Benefits were shared between client and contractors.