Concrete delivers world's tallest student accommodation

Constructing the reinforced concrete frame for what will be the world’s tallest student accommodation building is a considerable responsibility. Add to this the fact that the building will be the highest in the city of Leeds and, as such, one of the city’s most noticeable and iconic structures, the enormity of the task facing the design and construction team is clear.

The Plaza phase two project is being undertaken by Shepherd Construction for the UNITE Group plc, the UK’s largest provider of student hospitality and accommodation. When it is complete, this impressive building will stretch some 100 metres above the streets of Leeds, making an extremely visible architectural statement which will emphasise the city’s standing as a forward-thinking centre of learning and culture.

The reinforced in-situ concrete frame is being constructed by specialist sub-contractor Metropolitan Developer Ltd. The frame comprises a slip-formed core and 37 storeys of post-tensioned floor slab and, as the company’s managing director, Michael Cannon explains, selecting the best methods and systems with which to create these slabs has been critical. “Any responsible contractor will be aware of the need to balance safety with productivity, particularly on a structure as tall and high profile as Leeds Plaza,” he comments. “The main contractor placed a great deal of importance on the use of full-height safety screens and we needed to arrive at a method of construction that would satisfy the obvious safety requirements, but would also mean not having to compromise on productivity.”

“After considering a number of options, we decided to use a combination of Ischebeck Titan’s full-height, mesh-faced safety screens to provide the edge protection for the working areas in conjunction with the Titan HV soffit panel system to create the slab formwork.”

The use of full-height safety screens has become increasingly popular in recent years, especially for multi-storey structures, where they offer exceptional protection for the workforce at high levels and enhance safety for the entire site. In addition to providing edge protection in the areas where frame construction is taking place (erecting and striking formwork, setting reinforcement, pouring, etc.), the screens also create a safe working area for immediate follow-on trades as they cover several storeys at the same time.

The screens also have a more than useful spin-off for productivity. The fact that they form a full deck to soffit barrier gives the workforce greater confidence and enables them to work without hindrance, whilst the fact that they cover several storeys means that they do not have to be moved as often as traditional edge protection systems, placing less demands on crane time.

Typically, full-height screens are moved up the structure as casting of slabs progresses and are replaced at lower levels by other edge protection systems. However, at Leeds Plaza, the building’s outer cladding is following swiftly on from slab casting with the Titan full-height screens being utilised as edge protection, providing excellent benefits in terms of safety and speed of construction.

The use of mesh-faced screens, as opposed to those faced with solid materials, has proved to be an added bonus for the Leeds Plaza project. Mesh allows natural light into the working areas between decks and provides ventilation to keep dust nuisance to a minimum whilst still offering a very effective barrier against wind.

The employment of full height safety screens almost always necessitates the use of smaller tables or soffit panel systems to create the formwork on which floor slabs are cast. As Jim Cannon has stated, at Leeds Plaza, Metropolitan opted for the Titan HV system. The company’s contracts manager, Geoff Gray, comments, “HV’s aluminium construction provides a lightweight panel that can be lifted into place by a single operative from below the intended slab. It also has a simple and positive striking procedure which ensures that the panels cannot become accidentally displaced. These factors, in combination with the system’s versatility, mean that we can deliver good levels of productivity and maintain a safe working environment from working at height and lifting perspectives.”

“Thanks to HV we have been able to maintain a steady schedule of work, casting an entire floor slab per week and we are on target to complete the entire frame by the end of 2008.”

Plaza phase two is due for completion in Summer 2009. When finished, the £30m project will provide accommodation for 557 students and, together with phase one, which opened in September 2006, will create a student village for some 1,300 students. In addition to providing students with high quality accommodation, Plaza phase two will liberate an estimated 300 private homes, easing pressure on local housing stock.