Series
•How we made it: The Featherstone Building
The project
The Featherstone Building is a cutting-edge new build commercial development close to Old Street Station. Works included the demolition of two existing buildings and the
construction of a five to ten storey building with a single level basement. The existing retaining basement walls were kept and the basement level lowered.
The floor plates are in-situ reinforced concrete (RC) flat slabs with an aesthetic exposed soffit which also provided flexible services distribution, acoustic separation, and fire protection.
- Location: Islington, London
- Client: Derwent London
- Architect: Morris+Company
- Size: 15,938 m2 GIA
- Stage: Complete
- Time Frame: 2016-2022
The process
Exposed concrete frame
An RC framed building with exposed concrete elements that required careful detailing to meet architectural requirements.
To maintain slender slab depths and avoid post-tensioning, the design was refined; adjusting column locations, analysing stresses and modelling deflections to achieve a 9m x 9m grid layout. Allowing for a flexible open workspace while keeping slab depths at just 325mm.
GGBS cement replacement
Various levels of GGBS were used in the concrete mix with 30% in the soffits, 50% in the columns, 70% in the piles and 75% in the pile caps, reducing the embodied carbon of the concrete frame.
Site constraints
Network Rail and The Northern Line runs directly below the entrance façade, with a 3m exclusion zone around the tunnels.
Cantilever pile caps were used to set back the piles and minimise the impact on the tunnels. The basement slab was used as a transfer structure, increasing its depth to 1.5m
Heating & cooling system
Slabs were designed to incorporate an approx. 60km network of pipes, through which cold or heated water can flow, enhancing the concrete’s thermal mass.
A series of soft spots providing future flexibility for floor connectivity have been designed at second, third, fourth and tenth floors.
The impact
The Featherstone Building perfectly represents what we want from a modern commercial space, whilst still echoing the neighbouring historic buildings and working with the surrounding constraints. It creates a light-filled open workspace with the 9m x 9m grid – fostering collaboration – and offers adaptability for future needs, reflecting a long-life, loose- fit principle. The exposed concrete frame is utilised by the high-tech heating and cooling system and the use of modern methods of construction have ensured its lasting prominence as a top commercial property in the area. Achieving net-zero status, the building has been honoured with BREEAM Outstanding and LEED Platinum certifications, underscoring its excellence in sustainability and environmental performance.
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