Technical Refurbishment

>

certain existing walls to allow visitors to access from other areas of the library; installing security systems including access controls and CCTV to protect the many valuable books on display; plus other environmental and M&E systems. Sometimes, this strategy meant making

some tough decisions, such as when, late in the design, Shepherd discovered that the plaster-boarded ceiling of the corridor running around the outside of the Picton reading room hid a beautiful and ornate barrel vault. “We knew there was a void underneath and had already designed M&E services to run through it, but we had no knowledge of the barrel vault. Unfortunately, the M&E is fundamental to the building’s operation and there was no alternative route, so the vaulted ceiling will have to remain concealed in the finished building,” says Gerard. Other changes required less

consideration, such as the decision to demolish the entire 1950s and 1970s buildings, whose very low ceiling heights and multiple changes in level made them unsuitable for a contemporary library. “This made it reasonably easy to draw a line as to what structures should be removed and what should be retained,” says Austin-Smith:Lord’s Pownell. Much more onerous was the demolition

of these buildings, which had to be carried out in accordance with a strict vibration monitoring protocol developed to protect the valuable collections of artefacts, paintings and sculptures in the neighbouring World Museum Liverpool and Walker Art Gallery buildings.

Dome and dry

Repairs to the domed roof of the Picton Library over the years had created a patchwork of zinc, bits of lead, Georgian wiring and pieces of perspex covering holes in the glazed oculus. To restore the roof and ceiling

in its entirety, a huge 36m-wide trussed tent structure was installed, designed to span the Picton Library building and allow the roof to be dismantled and repaired without work being affected by the elements. The bespoke tent structure is thought to have been one of the largest in Europe, and according to Gerard, was an “amazing feat of engineering”.

The problem was that the

scaffolding needed to create the support for the tent structure had to be tied in to the existing buildings to provide support, but listing consents made it near impossible to find appropriate locations to land tubes or strut bars. “On a typical build you might

fix into a concrete column or wall, but here we had 1872-listed stone,” says Gerard. “It meant we were limited to much fewer fixing locations that each one had to be agreed with the conservation officer and the neighbouring buildings. It meant scaffolding provider HT

36 | SEPTEMBER 2012 | CONSTRUCTION MANAGER

“Unfortunately, the vibration trigger

was probably set too low and there have been hundreds of triggers throughout the project, which disrupted work to the extent that we had to frequently liaise with client team over course of the first couple of months,” says Gerard. “However, the client has gained an understanding and trust that Shepherd were not doing anything dangerous or outside of our method statement and work has always been able to continue.” Data from this exercise is being collated to capture best practice for use on future projects. As work progresses ahead of its

With no accepted British standards or guidance for this type of monitoring, a professor of acoustics from Liverpool University was called in. He recommended that several seismographs linked to computers be installed in the two neighbouring buildings. If a vibration limit was triggered, the computer would send text messages to the neighbouring buildings, the council and Shepherd’s construction manager and work was suspended until the cause of the vibration was investigated. To minimise possible disturbance during the demolition, Shepherd used computer-controlled Brokk demolition equipment and a long-reach excavator fitted with a rotating pulveriser to carefully separate the side walls of the library from the adjoining buildings, so that the rest of the demolition could be carried out in relative isolation.

The project involved extensive demolition works at the rear of the library

expected completion towards the end of the year and re-opening in April 2013, there’s already a sense that the architect’s aspiration to create contemporary spaces that both complement and contradict the existing architecture has been successful. This is most apparent in the newly

created children’s library in the basement level of the Picton Library. Previously closed to the public, this sunken, circular amphitheatre-like space will retain many of its unique features, which include ornate architraving, steel ceiling trusses and a tiered layout, but it has also been enlivened with a new performance stage, disabled access ramps that swirl down towards the centre, modern ICT stations and feature lighting. “Liverpool’s head of library services had the vision that this country’s libraries are missing an entire demographic of people, and inventive, exciting spaces like this are what can help attract them back,” concludes Gerard. CM

The tent structure covering the Picton Library’s domed roof is thought to be one of the largest in Europe when it was erected.

Scaffolding had to devise a very elaborate and technical design for the temporary works.” Once the scaffold was up, the

Haki 750 deep beam roll-out roofing was moved into position on wheels, and the restoration was carried out unimpeded.