Brewery Wharf, Leeds

 

Architects and engineers will be familiar with working on tight, pinned in sites.  Indeed, there may be more extreme situations than the one faced by the designers of Brewery Wharf.  But try it out for size: a 9,600 sq m site, bordered on one side by a busy road and bridge, on another by a river and on the third by a neighbouring hotel construction site.  You're building on water retentive gravel and the plans demand a car park basement covering the whole footprint.  Planning consent places a rigourous cap on building height and an acoustic performance that exceeds the new Part E regulations.

 

This was the challenge confronting Robinson Design Group when awarded the job by Totty Construction of designing and building 326 apartments across five buildings on the banks of the River Aire in Leeds.  Taking its name from the nearby Tetley's site, Brewery Wharf was scheduled in three phases over 38 months.  The only way to embark on such a large-scale project was to break it down into individual elements to identify the most cost-efficient construction methods.  Simplicity and buildability were the emphasis throughout the process.

 

Brewery Wharf's ultimate client, Barratt Leeds, automatically specify the use of concrete over steel in their apartment developments for two main reasons one to achieve the maximum ceiling height and avoid cluttering internal spaces with intrusive bulkheads and beams, and the other related to concrete's acoustic properties.  So Robinsons knew the material they had to work with what remained to be decided was the exact specifications to meet the constraints posed by the site.

 

The development's location beside the River Aire meant building on porous open textured gravel with a great deal of water retention.  Water levels could rise at any time.  Into this an underground car park had to be built, covering the entire site.  Brian Smith, Robinson's Design Director, decided a water-resistant structure using a standard C40 blended mix would do the job, without the need for water-proofing membranes or admixtures.  Smith says he is not a 'great believer' in the use of admixtures, primarily because they don't stop the concrete from shrinking as it cures. 

David Begg, project manager at David Ashley, the concrete sub-contractor on the project, agrees, adding "the problem with admixtures is that they need a plasticizer, which means that the concrete takes longer to reach its strength.  We were achieving 28 Newtons within three days at Brewery Wharf, which I think is pretty good."  Reinforcement was specified at 100mm centres instead of a more typical 200mm in the basement slab and walls, to prevent cracking and additionally help guarantee a water-proof structure.  Finally the basement slab laid over the pile caps was designed to resist uplift forces from water.

For the structure above ground level, Smith's analysis of requirements led him to a 225mm RC flat slab solution.  The attractiveness of this approach was in the ability to keep floor heights down and realise the clean lines needed in the apartments.  The design enabled a 2975mm floor to floor height and a continuous soffit in apartment ceilings, uninterrupted by unsightly downstands.

One unforeseen element in the initial design, and of which Smith is particularly pleased with the outcome, was the need to incorporate an element of rigid frame action into the project.  The planning-approved blueprint presented a restricted opportunity to incorporate sheer walls and shafts.  Working closely with contractor Totty Construction, Smith responded with a design that increased column width while still being comfortably accommodated within the flat layout.

 

Smith comments "We did some very interesting and useful work in the process of resolving this lateral strength issue.  It's broken new ground for us in terms of medium-rise projects and I'm looking forward to applying this approach elsewhere."

 

The flexibility of the concrete solution also came into play when designing a concrete transfer structure to facilitate clear driveways in Brewery Wharf's basement car park.  Superstructure columns needed to be diverted via a series of 850mm transfer beams to columns in the basement.  Standing under one of these beams beneath the tallest block, St. James Quay, it's impressive to think that nine storeys of vertical weight is being diverted 2.5 metres sideways before reaching the foundations.

 

Another point of interest was the decision to replace steel construction for the roof-top penthouse apartments with concrete after Phase 1.  It was felt that concrete was more architecturally compatible with the scheme overall besides the fact that life was simplified with one less contractor on-site.  And, in acknowledgement of the confined nature of the site, it was decided to keep the use of rebar down to the moderate level of typically 3% or less by weight of cross sectional areas for columns and 130 kg/m³ for floor slabs.  Not only did this mean less reinforcement being stored on the site, but it also made the concrete easier to cast, leading to a high-quality end result.

 

Of course, the new occupants of Brewery Wharf may relish all the brashness and excitement of city centre living, but don't want to hear noise when they are at home.  Barratts set demanding acoustic requirements for the project of a maximum of 34-35Db for external walls and windows and 53Db airborne level difference for internal/party walls.  Blockwork walls and a floor acoustic screed help achieve these targets, but the main contributor to quiet urban living is ultimate sound barrier provided by the flat slab and concrete frame construction.

 

The third and final phase of the development, containing 98 apartments, is due for completion by mid-August 2005, bringing this £60 million project to a close.  Now that the external works are complete and the scaffolding is down the aesthetics of Brewery Wharf can clearly be seen a contemporary 'warehouse/industrial' feel through the use of a simple palette of materials including metric brick and terracotta rainscreen panelling.

 

For the inhabitants, the whole development represents both a pied à terre and a place to get away from it all, right in the heart of one of England's biggest, buzziest cities.

Client: Barratt Leeds

Contractor: Totty Construction Group

Architect: Robinson Architects

Structural Engineer: Robinson Consulting

Project Manager:  Turner & Townsend

Concrete contractor: David Ashley

Print this page | Email to a friend