Sutton approves 359-unit office building conversion

JRL Group and Halcyon Development Partners have secured planning approval to convert and extend St Nicholas House in Sutton into a 359-unit co-living development, combining the reuse of a vacant office building with new residential, commercial, and community accommodation.

The scheme, designed by Assael Architecture, will involve partial demolition, refurbishment, and extensions reaching 15 storeys. Sutton Council approved the application under delegated powers, following a consultation that attracted more than 100 representations in support and one objection.

The former office building dates from the 1960s and occupies a prominent position in Sutton town centre, close to St Nicholas Church and surrounding commercial and civic facilities. The redevelopment will retain substantial parts of the existing structure rather than demolishing the building in its entirety.

The approved plans will introduce 359 co-living units, together with shared facilities and commercial accommodation. The scheme also provides space for a café, co-working activities, and a permanent home for The Sound Lounge music venue.

Approximately 1,400 sq m of public realm improvements are included in the development, with a new pedestrian route intended to improve connections through the site. The works will alter the relationship between the building and surrounding streets, providing additional public-facing accommodation at ground level.

The application, reference DM2025/00611, describes partial demolition and extensions of five, eight, and fifteen storeys alongside refurbishment and change of use of the existing building. The approved proposals also include landscaping, amenity space, cycle parking, and associated external works.

Unlike an entirely new development on cleared land, the Sutton scheme must accommodate the constraints of the existing building while introducing additional floor area and a different mix of uses. Retention provides an opportunity to preserve serviceable construction, but the proposed alterations require the old and new structural elements to function together.

The engineering design must establish how the retained structure will accommodate revised loading conditions. Additional storeys can increase the forces transferred through columns, structural walls, and foundations, while partial demolition may alter the building's stability during construction.

Temporary works and construction sequencing will therefore require careful coordination with the permanent structural design. Removing parts of an existing building before new elements are installed can change how loads are supported, making the order of demolition, strengthening, and reconstruction an important consideration.

The precise strengthening system and construction methodology have not been detailed in the publicly available project information reviewed for this draft. These arrangements will need to be established through the technical design and delivery process rather than assumed from the architectural proposals.

The redevelopment will also require the existing office accommodation to be adapted for residential use. Co-living developments typically combine private living accommodation with shared amenities, introducing different requirements for building services, circulation, ventilation, and internal layouts.

Existing office buildings may have servicing arrangements based on comparatively large floor areas and centralised facilities. Subdivision into residential units changes the distribution of water, drainage, electrical, ventilation, and other services, requiring these systems to be coordinated with the retained building fabric.

Fire safety is another significant consideration in a change of use involving residential occupation. The design must address the requirements applicable to the proposed accommodation, including the separation of uses, evacuation arrangements, means of escape, and the relationship between retained construction and new elements.

The inclusion of commercial premises and a music venue adds further complexity. These uses can have different occupancy patterns, access requirements, acoustic considerations, and servicing demands from the residential accommodation above.

The detailed design must therefore coordinate the operation of different parts of the building without compromising the requirements of individual uses. Acoustic separation will be particularly relevant where residential units share a structure with a music venue, although the specific measures selected have not been published in the information reviewed.

Assael Architecture has developed the design around the retained building and its town centre setting. The proposed massing, façade treatments, and landscape arrangements are intended to integrate the extended structure with neighbouring buildings and improve its relationship with the surrounding streetscape.

The Grade II*-listed St Nicholas Church forms an important part of that setting. The design has been developed to consider views towards the church and the relationship between the larger residential building and the historic environment.

The retention-led approach is also intended to reduce embodied carbon compared with complete demolition and reconstruction. Retaining serviceable structural elements can avoid some of the material production, transport, and replacement construction associated with a new building.

The scale of any reduction depends on the amount of fabric retained, the strengthening and adaptation required, and the materials used for the new extensions. The project information reviewed does not establish a verified carbon saving, so the proposed strategy should not be represented as delivering a quantified reduction at this stage.

Building reuse also requires decisions about the condition and remaining serviceability of retained elements. The original structure must be assessed against the demands of the new use, with the technical design determining which components can remain and where replacement or strengthening is necessary.

Assael director Ed Sharland has identified the constraints of the retained structure as a central consideration in the design. The practice has sought to balance those requirements with the proposed residential accommodation, new façade treatment, and public realm improvements.

The development forms part of a wider programme being pursued by JRL Group and Halcyon Development Partners. The companies have also brought forward proposals for a separate 329-unit co-living scheme in Woking, extending their activity in residential developments incorporating shared facilities.

At St Nicholas House, the planning approval allows the development team to progress towards the remaining technical and construction requirements. The application is a full planning application, rather than outline consent, so the project should not be described as awaiting reserved-matters approval.

Construction will nevertheless depend on satisfying the applicable planning conditions, completing the detailed technical design, securing the necessary building control approvals, and finalising procurement and site arrangements. The developers have not confirmed a construction start date in the latest information reviewed.

The development will combine structural adaptation, additional building height, new residential servicing, and improvements to the surrounding public realm. Its delivery programme will need to coordinate those elements while working around the constraints imposed by the existing building and its town centre location.

Planning consent establishes the approved development proposal, with the next stages concerned with translating the retention-led design into a workable construction programme. The finished scheme is intended to bring the vacant office building back into use while accommodating new residential, commercial, and cultural facilities.