Oakfern Housing Association, part of the Sentinel Housing Group, has commissioned a 294-unit housing project in Basingstoke using light steel framing as the chosen construction system. The project consists of a mix of 55% social/45% private housing units, ranging from assisted bungalows to 4 to 8-person housing and 4-person apartments.

Architects for the project, HTA, worked closely with structural engineer Michael Barclay Partnership and contractor Walter Llewellyn Ltd to optimise design and buildability in this novel project. Forge Llewellyn Ltd was selected as the light steel framing supplier because of their experience on similar public-private housing projects, and their willingness to develop the design concept in the early stages of the project.

A strict dimensional discipline was devised in order that all bathrooms were of the same size and layout. The front-back dimensions were also fixed on all units so that house types could be linked without changes to the roof profile.

The buildings consist of eight basic house of apartment types, all in light steel framing, with some variation for corner units. Phase 1 of the development is now complete, and Phase 2 involves ‘mixed use' retail and apartment buildings to re-create the traditional streetscape in modern style. The façades comprise a mixture of brickwork, render and timber. In some buildings, the roof space is utilised by means of attic roof trusses.

The project was conceived as a novel economic partnership following the ‘Egan' principles between the constructor and the client.  The constructor is guaranteed a fee, but the profits from the project are returned to the Association to enable the funding of infrastructure and community facilities. The project started on site in May 2001 and Phase 1 was completed in September 2002. The use of light steel framing ensured early completion of the first phase and return on the investment, leading to reduced cash flow to the client in this major project. Phase 2 is underway.

The light steel framing consists of 100 mm C sections in the walls, and 200 mm C sections in the floors. Positions of load-bearing walls are rationalised in the house plans, and floors span up to 4.5 m. Floors were installed as large cassettes to speed up the construction process. Open attic trusses create habitable space in roofs and provide private balconies.

The houses are typically 8.2 m deep on plan and 5.2 to 5.7 m on façade. The same basic house form is used in 2 and 3-storey configurations. The apartments are different in form, with 4 apartments on each of the 3 floors. Unit sizes range from 50 m2 for single-person flats to over 138 m2 for 5-person houses.

All bathrooms and staircases are identical throughout the project, which achieves economy in production, and rationalises interfaces and dimensions. In this project, the bathrooms are fitted on site, but they could also be produced as modules that are fitted out off-site. Pre-fabricated steel stairs were installed in the apartments.

A high level of thermal insulation is provided in the external elements, leading to a U value of 0.2 W/m2°C , much better than the value of 0.35 W/m2°C in the Part L of the 2002 Building Regulations. Similarly, in the multi-occupancy dwellings, the ‘built-up' floor and double skin walls achieve a sound reduction of over 60 dB, which is better than Part E of the Regulations. The rendered façade was installed on insulation attached directly to marine grade plywood screwed to the light steel frame.

Key information

Number of storeys	20
Units	294
New-build home

    Major Affordable Private Housing Project