The Greenhouse, Cambridge Heath Road. CLT Atrium. Image Jim Stephenson
One of the few new timber framed offices in the UK, The Green House is a revival of a disused and derelict 1960s office block. Refurbished and extended with a cross laminated timber frame, it delivers an environmentally exemplary office space.
Owned and managed by The Ethical Property Company, it enables them to meet the rising demand for flexible and affordable workspace for social businesses, charities and not-for-profit organisations in London. The building also matches their high standards for environmental performance and joins their growing portfolio of properties throughout the UK. The redevelopment of The Green House, including the retention of the existing concrete frame and the new extension in timber, has saved 2,200 tonnes of CO2.
Chosen for our expertise in offsite construction and cross laminated timber design, Ramboll carried out structural surveys, undertook extensive research on the existing building and assessed the proposed new building use against existing building loads and structural capacity. This involved structural, civil, geotechnical, and environmental engineering advice, working in close collaboration with Waugh Thistleton Architects and contractor B&K Structures.
Within the building’s almost 50,000ft² is enough modern and flexible workspace for up to 50 social change organisations to work under the same roof, sharing generous communal facilities and community spaces.
The existing concrete structure has been refurbished with the addition of a six-storey front extension, as well as an additional steel-framed storey on top for additional workspaces that offer uninterrupted views of the city. The rear extension comprises a six-storey cross laminated timber frame building that significantly increases office space. The timber frame was made possible through the design of bespoke column to column connections using standard off-the-shelf components. This connection detail enabled fast installation of the columns and estimated programme savings for installation of the columns of over 50%.
The new extension is structurally independent of the existing frame. Careful detailing was required to allow for the differential movement of the two frames at the junction and also to avoid adding any new load to the existing frame. The addition of the top extension required meticulous back analysis of the existing frame as well as targeted surveys to mitigate risks about the future life of the frame.
Internally the layout provides flexible accommodation to suit varying sized organisations, with a light and airy central timber atrium to enhance networking. The timber extension includes an innovative spectacular cantilevered six-storey feature stair in the centre of the building. This timber staircase includes a pioneering bonded-in rod connection to allow the glulam treads to seamlessly cantilever from a singular CLT spine wall, developed by Ramboll. A full scale mock up was undertaken to test and prove the strength and construction sequence.
Conrad Peberdy, Managing Director at The Ethical Property Company said, “These are significant transactions for Ethical Property which will enable us to upscale our activities in order to meet growing demand from potential tenants. This is vital at a time when property in the capital is increasingly out of reach of voluntary and community organisations due to rising rents and loss of office space."