黑洞社区

<b>Project management</b>
In 1997, Harlow Council organised an architect-developer competition for a new foyer on part of the cleared site of the old technical college in Harlow town centre. A foyer provides affordable housing, training and access to employment for young people leaving home, and the brief set by Harlow was for 76 foyer flatlets and 40 slightly larger 鈥渕ove-on flats鈥� with reduced levels of support.
East Thames Housing Group won the competition with architect Wilkinson Eyre鈥檚 design of two curved blocks, clad in aluminium and roofed in sheet steel. The scheme was granted detailed planning approval in July 1998.
The project was envisaged as a partnership scheme from the outset, and in 1998 the partner design-and-build contractor, Countryside Partnership Housing, initially priced the scheme at 拢5.6m 鈥� some 拢800,000 above the budget of 拢4.85m.
Foyers are notoriously difficult to fund, and by June 1999, when the funding package was eventually confirmed, the contractor was still unable to offer acceptable cost-saving options to bring the scheme within budget.
By the end of September 1999, after several meetings with the contractor and its designers, many of the previously identified savings had been eroded by inflation and by underpricing in the original costing. More radical savings would have resulted in either an unacceptable reduction in quality of materials, or a reduction in the number of units, either of which would have necessitated a time-consuming fresh planning application. Reducing the number of units would also have made the scheme unviable. In any case, neither of these savings options would have brought the scheme on budget.
East Thames had given a commitment to its main partner, Harlow Council, that it would begin work by 10 February 2000, as part of the funding would have been lost if the start date had been any later.
With only four months to the deadline, East Thames might well have been facing failure, had it not been for a lunchtime seminar in its offices given by David Levitt and Robert Lombardelli, two of the consultants working on the Leeds City Centre Accommodation for Single People at Affordable Rent project. The Caspar scheme, for the Joseph Rowntree Trust, used innovative semi-volumetric timber-framed modular construction. The curved footprint of the building bore an uncanny resemblance to the Harlow Foyer scheme, and the reduced lead-in, contract period, and costs claimed for the project made it an attractive solution to the problems 鈥� if it could be made to work.
The contractor had by then agreed to step aside to enable the housing association to seek alternative procurement strategies.
East Thames approached the consultant design team for the Caspar scheme along with its timber-frame trade contractor, Volumetric, and asked them to assess whether this form of factory-built construction might be suitable for the foyer building. In addition East Thames asked for a cost plan, based on the team鈥檚 Leeds experience, to establish if savings of about 20% could be made on the final cost quoted by the original partner to bring the project back on budget.
Within a week, the new design team had confirmed both the viability of volumetric timber-frame construction and a construction period about 30% faster than that for conventional construction. The new cost plan also provided the opportunity to restore some of the features of the competition-winning scheme that had been lost in cost-savings exercises.
By October last year, a new partnership had been formed with the full consultant team and the timber-frame subcontractor from the Leeds project. The redesign of the Harlow Foyer began to accommodate the new form of construction.
In November, the partners interviewed potential contractors, and on the basis of their attitude to partnering, capacity, resources, profit and overhead percentages, selected Walter Llewellyn & Sons to join the team as main contractor. By early December, the expanded partnering team had also interviewed and selected the specialist subcontractors, all of which except Volumetric were new to the project.
Although Harlow Council was very supportive of these efforts to resurrect the project, its members had some misgivings about the use of timber-framed construction. But after some negotiation and a visit to the Volumetric factory in Potton, these misgivings were dispelled.
On 13 December 1999, the full team of partners met with an independent facilitator, John Carlisle Partnership, for the first 鈥減artnering day鈥� to ensure that the project objectives were agreed, to prepare the partnering charter, to agree a dispute resolution mechanism, and to identify the critical success factors for each of the partners. One further issue was identified at the partnering day as crucial to the success of the scheme and the partnership: the form of contract. The partners were unanimous that the standard forms were not the vehicles to deliver a partnering project, and agreed to look at alternatives.
Taking a cue from the Latham report Constructing The Team, which stated that the new engineering contract contained virtually all of his principles for best practice in a modern form of construction contract, a one-day seminar was held with the solicitor, the design team, and the main and specialist subcontractors to discuss the NEC form of contract. The NEC form, using option C (target contract with activity schedule) was subsequently adopted.
The period in the run-up to and immediately following the millennium celebrations saw little let-up in the frantic pace of the project, which included a successful application to the Housing Forum 鈥� the body set up to promote the Egan agenda in housebuilding 鈥� for the Harlow Foyer, and its sister project, Redbridge Foyer, to be awarded demonstration project status.
Through the sheer determination of the partnership team to meet its commitments to the project and to deliver a landmark building for the young people of Harlow, Llewellyn took possession of the site on 10 February 2000. So it was that East Thames met its promised start date, thus securing the 1999/2000 funding allocation that might otherwise have been lost.
The partnering team and the organisations it represents are very proud and pleased with the finished building, as are the young people of Harlow themselves.
Looking back, it is frightening to think of the many occasions when things could have gone wrong 鈥� and were it not for the absolute trust that East Thames had placed in its partners and they, in turn, placed in the housing association itself 鈥� many of them would have.
<b>Design adaptation</b>
It is highly unusual for an architect to have full design control over the development of another architect鈥檚 concept design. The challenge for Levitt Bernstein was to maintain an excellent concept designed by Wilkinson Eyre, but to develop it in response to an evolving client brief and, more particularly, to adapt it to timber-frame construction for the benefits of speed and factory finish. 黑洞社区 form The scheme divides into two parts: a foyer of 76 studio flats with common facilities accessed through a single point of entry off Playhouse Square; and a 鈥渕ove-on鈥� block consisting of 40 one-bedroom flats entered via their own staircase. This division reflects the progress of young people through the foyer system towards the final goal of self-sufficiency. The interlocking volumes of concave six-storey foyer and convex four-storey 鈥渕ove-on鈥�, all clad in aluminium panels, form the public facade to an important cultural square in front of the Playhouse Theatre.
Construction It was infeasible to construct the six-storey foyer block entirely in timber frame. Instead, an insitu concrete transfer slab at first floor provided the structural freedom to accommodate the wide variety of room requirements on the ground floor and a regular grid for the studio flats above. The radial nature of the plan made it impractical to prefabricate entire flats as volumetric modules. Instead, the flats, with their wedge-shaped plans, were designed with serviced cores and entrances towards the centre of the radius. This enabled these heavily serviced kitchen and bathroom cores to be factory-finished using a volumetric process. The 鈥減ods鈥�, each containing two kitchens and two bathrooms, were delivered to site, then craned into position, services lined up, then stacked round the circulation core containing the lift. Radial party walls, external, storey-height structural walls and floor sections, delivered as 鈥渇lat packs鈥� on low loaders, were then added to complete each flat in timber frame.
In this way, each storey was made weathertight as soon as the next was installed. Two stair cores added bracing to the stacked structure.
Once this semi-volumetric shell was erected, the elevations were clad in metallic finish, flat aluminium Alucabond panels. Monopitch trusses formed the roof structure. The roof, eaves and soffit were then clad in tern-coated stainless steel.
The 鈥渕ove-on鈥� building, also a metal panel-clad, semi-volumetric, timber frame, was stabilised by a four-storey steel and concrete stair tower and access decks.
Timber frame An unprecedented technical problem of dimensional co-ordination was posed by marrying a factory-precise system of metal cladding panels to the timber frame, which was erected on site with tolerances that could vary by as much as 40 mm over the entire facade of the building. No such problem had been encountered at the Caspar project in Leeds, where timber cladding could be adjusted easily on site to respond to the supporting timber frame. The solution at Harlow was to use recessed metal filler panels, 50 mm wide, to make up discrepancies at the joints between the facets of the cranked elevation, the panels being wide enough for the discrepancies not to be noticeable. Narrow corner panels used at the corners of the block performed a similar function.
<b>Cost comment</b>
As the original concept building was a design competition winner, many high-cost features could not be abandoned. The complex stainless steel roof and the aluminium cladding added cost, as did a commitment to low energy consumption and a high standard of finishing.
The previous estimate of cost for the building constructed by traditional methods was 拢5.6m. By delivering it at 拢4.85m, a 13.4% saving was made for substantially the same accommodation 鈥� as well as a reduction in construction time.
Based on the draft final account figures, the building cost is 拢966/m2, or 拢1011/m2 including fittings and furniture.
<b>Procurement</b>
From a standing start in November 1999, when East Thames Housing Group approved draft proposals to redesign the scheme in timber frame, a site start had to be made on 10 February 2000. The entire consultant team for Caspar project in Leeds was taken on, and, given the tight programme, the involvement of timber-frame manufacturer Volumetric was almost a necessity as long as price and terms could be agreed within the budget.
The new team of consultants was determined to grasp the Egan agenda, which included involving the contractor and subcontractor in solving design problems within the initial cost plan. Accordingly, a contractor was selected that would be willing to give up its normal contractual position in exchange for a full place in the project team.
With Walter Llewellyn on board as main contractor, the design progressed by an iterative, or back and forth, process. Design proposals were brought to the table for discussion. Specialist task groups would be formed to work out the detail. Performance and cost were evaluated, and decisions taken.
The reduction or elimination of risk factors was a key driver when preparing the design details, as it encouraged contractors to reduce their prices. An example of this was that they were aware that late design changes would only occur with full consultation, thus allowing alternatives to be considered and making programming easier.
It was realised that, to meet the programme, the detailed design would not be signed off before fabrication of the major components began. So, a priority-driven design programme was developed by the team to ensure that sufficient detail was available when required, while ensuring that later design work and cost was not compromised.