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You throw sand around, and when you can't see it anymore, it's thick enough

Sutherland Lyall talks to Paul Monaghan and Stephen Ritchie from Allford Hall Monaghan Morris (AHMM) about the construction of Liverpool’s £60 million Unity development

Paul Monaghan explains how AHMM was appointed to design probably the biggest building currently under construction outside London: ‘It came from a recommendation by Tim Pyne, who we worked with on the Dome. He met someone in a restaurant who wanted to do two towers in Liverpool. We are both Liverpudlian and so there seemed to be a link there. So we met the client, Rumford Investments, which had planning permission for an older scheme. We got on OK and we agreed to do some initial work. They liked it and we got our design to planning in eight weeks and it took four weeks for permission.

‘Then Liverpool won Capital of Culture for 2008. There was an appetite [at Liverpool council] for a bit more. They wanted to use the building as a sign of regeneration - and to set a new benchmark for commercial buildings. And then we made the top of the building a lot more elaborate.

‘As usual, it took time to negotiate the price with Laing O’Rourke, which was already on board. Finally we were novated to Laing O’Rourke and we have been working for them ever since. We have had a very good relationship with them. We really are working with the supply chain and it really opens your eyes to how - because they have such buying power - they can negotiate with all those subcontractors.’

Project architect Stephen Ritchie adds: ‘Laing O’Rourke have their own preferred suppliers with whom they have deals.

But they got us involved with their subcontractor-selection process.

We didn’t have any fall-outs about who we picked.’ This has been a relationship based on a mutual grasp of the importance of maintaining design standards. Monaghan says: ‘They showed very early on that they understood the value of design.’ Laing O’Rourke project manager Mike Harrison had just come off another big project where he had seen that simply throwing expensive materials at a building design wasn’t necessarily the way to do it. Monaghan continues: ‘He saw this as an opportunity for Laing O’Rourke to place themselves in a different part of the marketplace. And so it has been an absolute joy to see such a turnaround compared with any other contractors.’

 

TWIN TOWERS The site is located one block back and one block across from the Three Graces on Liverpool’s waterfront. There are two stepped towers rising from a retail podium around the base, forming three sides to a hard-landscaped court. The 27-storey west tower, with its shiny penthouse block on top, is an apartment block that deploys a UnitÚ d’Habitation-style two-level crossover arrangement, with an access street every three oors. The 16-storey east block is an office and commercial building. Monaghan says: ‘There has been a massive middle-class migration into the city. So this scheme is only for private purchase. All but six of the apartments have been sold six months before the building is finished. Interestingly, the risk was seen to be in the office building - and the Northwest Development Agency provided a ú10 million grant to help build it.’

Paul Monaghan says cautiously: ‘The building has very slight nautical references.’ There is the aluminium-clad penthouse which is vaguely like a ship’s bridge. More direct is the series of wall images by Studio Myerscough in the residential lift lobbies which are based on designs for camouflaged First World War ‘dazzle ships’ painted by the Vorticist Edward Wadsworth, working as a wartime camouflage designer.

 

STRUCTURE The apartment tower was built using tunnel-form construction - all the way up to the penthouse, which has a three-level steel frame sitting on a concrete slab. The tunnels are at 5.4m intervals, which means the apartments are not anything like as narrow as Corb’s originals. Project architect Stephen Ritchie says: ‘Tunnel-form offers good acoustic separation between the flats and Laing’s adopted it rather than a frame approach. The office tower is a conventional concrete frame with flat slab floors.’

 

RUNNING WITH THE CONTRACT Laing O’Rourke was on board at the beginning and, although there was some talk of a two-stage negotiated tender, the contract was a bespoke form of design and build. The design team was put together in consultation with Rumford Investments, which uses the London quantity surveyor Goyne Adams on all its jobs. Ritchie says: ‘They were very keen to use local firms and Laing O’Rourke negotiated the services of the design team as a separate matrix.

Our appointment is not through the standard form: Laing O’Rourke drew up its own schedule of duties. We have worked well as a team. Often it is the case that teams assembled by the client don’t get on. But here everybody is a professional and they are all nice chaps.’

A crucial element in the contract has been the use of the construction-orientated central information and transaction hub, Asite. Ritchie says: ‘We post everything digitally. No paper drawings any more. All documentation goes through Asite. We define who is to get drawings, what action is needed and whether they are for review or for information; then they go on to the Asite server. At the other end, recipients are notified and plug in. It is a very effective way of distributing information - and it provides a great audit trail.

‘There have been teething problems. You are often opening huge drawing files, so it can be quite slow to access. Early on, Laing O’Rourke made the decision that if a subcontractor couldn’t open Asite they wouldn’t use them. I think they have moved from that policy because not all subbies are all that au fait with computers.’

The construction team ended up not using Asite for correspondence. Ritchie says: ‘We used Microsoft Outlook Express to email and write letters. Ideally, the system is set up for all correspondence to go through Asite but it’s a bit cumbersome, especially if the pipe to and from the office is too small. But generally I think Asite is the way forward, rather than posting paper drawings to each other; and it saves trees.’

The AHMM of-ce CAD system is Microstation. Ritchie says: ‘Most other people use AutoCAD but Microstation V8 has no problems with file conversions. And we have the entire drawing schedule in a Microsoft Access database. We use it because it’s extremely exible rather than using an Excel format.’

 

BUILDING AND SPECIFYING Ritchie says: ‘We got Schumann Smith to do the specification.

Architecture is such a long game that architects get to write a spec maybe every three years. It makes sense to employ someone who does it all the time. They don’t use the National Building Specification. Theirs is based on an American system they think is better - and they cite the fact that they have never been sued.’

A construction innovation was the prefabricated Hi-Point penthouse roof. Ritchie says: ‘The roof was made off site in large sections by Corus so it could be craned up and bolted together and the roofing joined up over a three-day period.

We decided on this approach because everybody was concerned about people working on the very exposed site. It went up without a hitch and was very effective. Corus Kalzip also did the whole pod envelope using a stainless-steel plank system, which was finished very quickly and we are very happy with it.’

Cladding by Dane Architectural Systems is different for each tower. The residential block with its cellular construction is based on a Kingspan Off-Site rainscreen system which involves -xing a steel storey-height and tunnel-wide prefabricated frame to each cell. It has internal panels, Kingspan phenolic insulation with an aluminium rainscreen on the outside and incorporates Sch³co windows. The commercial block is a straightforward Sch³co curtain wall by the big Sch³co fabricator. Ritchie says:

‘They have been very good and the cladding very, very closely follows the intent of our drawings. We didn’t choose Sch³co sections. I designed it in a very generic manner so it could have been built out of a window-wall system or a stick system or a unitised system.

‘That meant that each of the firms on the tender list could use the most appropriate system. So all our cladding packets came in on or below budget. We went to great lengths: along with Laing’s we went to visit them and explained what we wanted in great detail and that it was fine if there was a commercial advantage in doing it another way - as long it didn’t affect the design intent. I’m very pleased. It’s a remarkable job they are doing on the 16-storey commercial tower on an exposed site.’ Here the silver panels are PVF2-coated which has a metallic eck in it.

Ritchie says: ‘It’s a little bit of glitter beyond powder coating.’

The black panels are specially folded and welded and braced.

Flat roofs are waterproofed with Decothane. Ritchie says: ‘We chose it because we have been bitten with membranes.

I wanted something that bonded directly to the concrete and was robust enough to cope with site traffic - and which made the roofs as waterproof as possible, as early as possible. With a spray you can do that. And at the end you can recoat fairly easily. It’s extremely tough, and you use bonding tape for movement.’ As for hi-tech application technology, Ritchie says: ‘You throw sand around and when you can’t see it anymore, it’s thick enough.’

Ritchie says: ‘We have tried to line the entrances with honorific materials: stone floors, back-printed glass lining and, in the residential-tower entrance, timber decking lining the walls with the dazzle-ship pattern taken through to a backlit desk and column, on to some balustrading and emerging on to the street.

He adds: ‘Greenberg Glass has a system where they print the glass. It’s not a film or a ceramic frit: it’s rather like a laser printer and the whole thing has a seal coat so they cut the glass, print it and put it on the wall using fixing channels. We looked into loads of different products but they were very complicated and immensely costly and had long lead periods and so we went for the local firm which had the will to do it.’

Inside, the architect’s selections were occasionally changed and one case was the carpeting to the common areas of the residential tower. Originally, AHMM selected Miliken because of its range. But that was value-engineered to Brinton, which has a very similar carpet and is a regular Laing’s supplier.

OEP Joinery, a Laing O’Rourke choice, produced 1,600 doors for the whole job, with all timber doors in the residential block. The company also made the white laminate WC cubicles and doors in the commercial tower. Ritchie says: ‘They were made in Poland and are extremely good.’ Sanitaryware is by Armitage Shanks and taps are Grohe. Bathroom wall tiles in both residential and commercial blocks are matt-glazed Icolori from Focus. The dazzle-ship residential lift lobbies are also clad in Focus-sourced Icolori. Ritchie says: ‘Icolori has a wider range of colours and we matched the original dazzle-ship colours with RAL colours and then matched these with the Focus tiles.’ Here, minimalist Zumtobel strip lights were too expensive and Luxonic made up fittings with the same appearance.

Kitchens are by William Ball, a local outfit which, Ritchie says: ‘Tendered for the kitchen package and came in with a plain white lacquered-door kitchen at reasonable rates. They supplied what was asked for. They did a show flat and they matched the kitchen for less money. So competition works.’

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