Assael Architecture kept intervention to a minimum at Century Buildings, breathing new life into a conversion of two central Manchester offices to create luxury flats
Harry Fairhurst could not have anticipated the chain of events he began when he designed the National Building as the headquarters of the National Boiler and General Insurance Company. A terracotta-faced masonry building completed in 1909, it sits to the north of central Manchester on the bank of the River Irwell. In 1971 his practice, Fairhursts, completed a curtain-walled office block on the adjacent site - more tower-like than the National Building, but no taller. And now Assael Architecture has converted both buildings to combined residential use.
Renamed Century Buildings, they are part of Manchester's boom in central apartments for owner occupation and investment letting and boast the city's first £1 million-plus penthouse.All the flats have been sold or are under offer, with a local property paper advertising one-bedroom flats for £195,000 - almost twice the price of a purpose-built one-bedroom flat in Glen Howells' Timber Wharf (AJ 6.2.03), a couple of miles away at Castlefield in Salford. Location, location, location.
Assael's approach to the differing period pieces of the 1909 (listed Grade II) and 1971 buildings has been to respect them and touch as lightly as possible with any new interventions. This was far easier to achieve with the 1909 building than with the 1971 one, whose curtain walling, advanced at the time, would have been interesting to save but could not be upgraded to current standards in an afforable way. The building was stripped to the frame, reclad and replanned, but some original features remain, such as the stair cores and, very noticeably, the deep parapet to the front.
Century Buildings has two facades addressing two very different contexts. To the front (south-east) is Parsonage Gardens, an off-square square enclosed by similar-height offices - one of Manchester's few central urban green spaces. Immediately along the back is the Irwell, here channelled like a canal.
Assael began by adding a floor to each building. On the 1909 structure, this top floor pulled back respectfully from the rooftop towers at either end. (The addition is two stories high at the rear, forming duplexes. ) Project architect Ben Jones reflects that this simple lining through of building heights was perhaps partly a reaction to previous experience in London, where permission to add to a building's height is hard to negotiate.
But in Manchester, it was the planners who encouraged the idea of extending the 1971 building by three stories. Both buildings were substantial enough to support upward extension in steelwork.
The result on the Parsonage Gardens side is ambiguous, with different cladding above and below the parapet on the 1971 building.
Below the parapet the main cladding has some horizontality, corresponding with the 1909 building. The use of timber, besides adding a domestic note in a commercial area, chimes with the colour of the 1909 terracotta.
Above the parapet, the cladding, though set back in penthouse style, reaches up more as if the building were a separate tower. This effect of separation has been accentuated by setting back the new cladding for a bay between this and the 1909 building in a slightly darker colour, and through a more angular rooftop treatment. The cladding itself sits well enough with its heterogeneous neighbours.
The terracotta of the 1909 building was generally in good condition, needing a little local repair. The Crittal steel-framed windows were replaced.
On the riverside, ambiguities disappear and the buildings read separately as two of several along that stretch of the river. The floors of the 1971 building have been cantilevered out at each level and the parapet has been removed; it reads as a tower. The brick character of the 1909 building on the riverside has been respected - the new suspended balconies are shallow planes with unobtrusive clear-glass balustrades. The two new stories stand back from the brick facade beneath an oversailing roof.
This steeply sloping site down to the river edge leaves both buildings high and dry above the water. The older building looks warehouse-like, but it has always been an office;
neither building has ever needed physical connection with the water. Assael added a propped broadwalk wide enough for a potential restaurant tenant in the 1909 building to put out tables, as well as for people to walk past.Manchester City Council sees the potential for a high-level riverside walk here, between Blackfriars Bridge to the east and Calatrava's Trinity Bridge to the west. Waterside paths have been a successful feature of Manchester and Salford's recent renewal.
While the 1971 building exhibits the greatest external change, the 1909 building has changed most dramatically inside. In its former life as an office, spaces were lit back and front, from the street and the atrium. One space was accessed through the next, working out from the core. This dual-aspect daylighting has been retained but individual front doors have been provided by the dramatic device of bridging across the two atria. To avoid making new openings in this listed building, the bridges enter the building via existing window openings (made possible by generous floor-to-ceiling heights), feeding into a lobby to two or three flats. Within the flats, you step down to the original floor level.
(Assael planned the flats, with an interior designer adding further detail. ) The need to reconcile different levels led to some of the bridges being sloped, but this feels entirely fitting. The bridges' tubular steel and cable structure at each level (which also carries some service facilities) is a single, self-supporting framework in each atrium, independent of the existing masonry structure. Thus the bridge-ends simply rest on the floors - you step up onto them. Not surprisingly, fire engineering was needed to make the case for this whole approach.
The atria are unheated, providing natural ventilation for the flats (with fire closers on the windows). The rooftop extension features new glass atrium roofs, set off by uplighters.
Perhaps surprisingly, Century Buildings has just one entrance - the original main entrance of the 1909 building. Assael initially planned another entrance for the 1971 building. The cost of manning a second entrance would have been high, but an electronic entry system might have been used. As it is, occupants of the 1971 building have a long walk to their front door. The circulation space around the original staircase also feels a bit cramped and enclosed, particularly compared with the daylit atrium leading to it.
But such compromises always come when working on existing buildings, and should not detract from the impressive ingenuity Assael has exercised here, breathing vibrant new life into these two buildings - a sensitive response.
Summary based on tender sum Cost per m 2Percentage (£) of total DEMOLITION 17.35 2.09 SUBSTRUCTURE 4.80 0.58 SUPERSTRUCTURE Frame 36.81 Upper floors 14.90 1.80 Roof 30.12 Staircases 10.77 Atria bridges 37.29 4.50 External walls, balconies 170.38 20.54 Windows, external doors 27.70 3.34 Internal walls 40.61 4.90 Internal doors 39.22 4.73 Group element total 407.80 49.16 INTERNAL FINISHES Wall finishes 21.33 2.57 Floor finishes 43.90 5.29 Ceiling finishes 15.07 1.82 Group element total 80.30 9.68 FITTINGS AND FURNITURE 68.59 8.27 SERVICES Plumbing, sanitary, disposal, heating, electrical 120.84 Lifts 33.25 Group element total 154.09 18.58 EXTERNAL WORKS 8.57 1.03 PRELIMINARIES, INSURANCE 71.90 8.67 CONTINGENCIES 16.11 1.94 TOTAL 829.52 Cost data provided by Assael Architecture CREDITS TENDER DATE February 1999 START ON SITE DATE March 1999 CONTRACT DURATION 33 months GROSS EXTERNAL FLOOR AREA 18,168m 2PROCUREMENT Design and build TOTAL COST £12,099,322 CLIENT Nicholson Estates ARCHITECT Assael Architecture: John Assael, Russell Pedley, Phil Bangs, Ruiridh Hogg, Ben Jones, Gary Stanesby, Adrian Waters, John Desaleux, Tim Ashcroft, Jaimie Watler QUANTITY SURVEYOR, PROJECT MANAGER GTMS STRUCTURAL AND SERVICES ENGINEER WSP FIRE ENGINEERING Fire Safety Consultants ACOUSTIC CONSULTANT Hann Tucker CLADDING CONSULTANT Wintech INTERIOR DESIGNERS Mary Fox Linton, Tegerdine Associates LIGHTING CONSULTANT Isometrix PLANNING CONSULTANT Drivers Jonas MAIN CONTRACTOR CH Pearce SUBCONTRACTORS Cladding Parry Bowen;
frame steelwork LM Engineering; atrium bridge steelwork TP Aspinall & Sons; fireresistant windows Fireshield Glazing; balustrades Sovereign Stainless Fabrications; fire protection Fire Protection Service; mechanical Lorne Stewart; roof, external soffits Briggs Roofing; electrical Yates & Reece; terracotta repair Maysand; lifts Rubax Lifts SUPPLIERS Cables Norseman Gibb; metal decking Alusuisse; rrazzo Quiligotti; rubber flooring Dalsouple; single-ply roofing Sarnafil