Leading architectural practices Feilden Clegg Bradley (FCB), Alison Brooks Associates (ABA), and Macreanor Lavington Associates (MLA) have created an eclectic mixture of modern designs for an award-winning mixed tenure housing project on the former Inland Revenue site at Brooklands Road, Cambridge.
A common theme running through the 378 first phase housing and apartment project is the efficient use of living space and the mixture of private and commercial areas for this high value urban site.
This project also marked the first collaboration between Metek and a Precast concrete company in which the primary structure of most of the buildings is in pre-cast and in-situ concrete, and the façade walls are in light steel framing.
Building ABA01 was one of the first to be completed, and consists of 4 storeys with a penthouse apartment enclosed by a curved steel roof comprising Rectangular Hollow Section (RHS) beams, light steel purlins, and light steel infill walls.
The 3-storey FCB buildings emphasised the public amenity by creating communal first floor space and included 9m high chimneys feeding all apartments.
The structure of these chimneys was conceived using steel posts and light steel infills – the first known application of this technology in such tall chimneys. The patio doors required a light steel supporting structure capable of over 4m span which Metek provided.
The construction programme for the first phase of the project necessitated a tight 6 months to completion of the show houses from start on site, and a further 4 months to completion of the first phase of apartments and houses, which was achieved by the pre-fabricated nature of the hybrid concrete and light steel frame construction.
The Accordia project has won numerous awards, most notably a 2007 Civic Trust Commendation Award for East Anglia, a Housing Design overall winner award for 2006 and the RIBA Stirling Prize, 2007.
It consists of 166 apartments and 212 houses of which 30% are affordable mixed tenure. The build density is 67 units per hectare and unit sizes range from 50 to 360m2 in 1 to 5 bed configurations.
Construction Details
The project was designed to a high level of environmental performance and embraces the requirements of EcoHomes, BREEAM, and the Code for Sustainable Homes. It achieved a ‘Very Good’ BREEAM rating, and all houses and apartments provide for flexible and spacious living space to meet a range of user requirements.
The light steel infill walls ranged from 2.8 to 4.2m height and were mostly designed using 100mm x 1.6mm thick light C sections. Wide openings for patio doors were created using multiple C sections for posts and lintels without changing the basic construction technology.
Importantly, the as-built dimensions of the concrete frame were measured on-site, and sent back to Metek’s design-office for next day manufacture.
In this way, Metek could satisfy both ‘just in time’ delivery of the prefabricated light steel wall panels, and could also achieve dimensional accuracy for easy installation. This was essential to meet the main contractor’s tight construction programme. The curved roof of building ABA01 posed particular technical questions, which were solved by bending of the 200mm x 100mm RHS rafters to a radius of as low as 700mm.
Purlins comprising 175mm deep C sections spanned up to 6m between the RHS rafters, and their Autoform ends were screw-fixed to the face of the RHS. The roof was clad in copper sheeting attached to plywood that was itself screw fixed through the closed cell insulation to the purlins.
Small chimneys and roof-lights were directly fixed to the purlins. A canopy was also constructed using steel C sections bolted to the RHS members.
In the FCB buildings, prefabricated light steel roof panels spanned directly between light steel separating walls.
The chimneys used 100mm square SHS posts bolted to the concrete slab with light steel infills in the form of lattice members between the posts.
The steelwork also had to support the brickwork facia to the chimneys, which was supported directly on lintels attached to the steelwork.
Application Benefits
- Rapid installation of a dry building technology.
- Construction periods reduced by up to 30%.
- High dimensional accuracy of this prefabricated technology.
- Curved roof and variety of roof profiles.
- Variety of façade treatments.
- Chimneys of 9m height using steel.
- Increased site productivity.
- Predictability of process.
- Safer construction process.
- Increased quality and reliability.
- Good energy efficiency through ‘warm frame’ construction.
