Castle Lane, Westminster
Façade Retention

Falsework, Formwork & Retention

Castle Lane is located in the conservation area of Westminster and is being redeveloped as part of the affordable housing scheme. RDG was commissioned to design temporary works structures to facilitate the redevelopment of three blocks of flats and a single-story building.

The redevelopment required that the buildings be hollowed out to allow alterations to the internal structure. The client adopted a top-down demolition approach and a bottom-up approach for the proposed works. A façade retention was designed to support up to five floors of the building façade, as well as the parapet and chimney.

RDG was commissioned to design mobile access to facilitate the installation of the canopy steel along the length of all four platforms. A track-mounted independent was designed, with a GRP membrane to protect operatives from passing trains. The track and bogie system was bolted into the concrete platform at given centres to mitigate against overturning from wind loading and wind buffeting. The solution ensured simultaneous construction works remained unobstructed and the railway remained operational.

The design maintained the lateral load path created in the existing structure to facilitate the top-down demolition. This also avoided the need for new foundations on an already congested site. A gap between the façade and the horizontal walers was required to allow the new structural columns to be installed within the opening without compromising load paths. As the façade was not horizontally flush, the walers were also required to be cranked to follow the geometry of the building. A bespoke bracket was designed to negate tension forces in the anchors that would have been detrimental to the masonry. Extensive 3D models were created to evaluate the structural behaviour. Where possible, the scheme was tweaked to lower materials requirements to create an economic structure.