IN Brief:
- Tower Hamlets approved the deep retrofit of 10 Cabot Square on 30 October 2026 under application PA/26/00133/A1.
- The Howells design retains all existing foundations and more than 70% of the superstructure while adding two rooftop office floors.
- Howells estimates 28,000 tonnes CO2e avoided against equivalent new build; construction remains contingent on a pre-let.
Canary Wharf Group has secured planning permission for a major retrofit of 10 Cabot Square in London’s Docklands, allowing extensive alterations to the existing office building while retaining much of its structure. Tower Hamlets Council granted full permission on 30 October for a scheme designed by Howells that includes partial demolition, replacement façades, reconfigured internal floors, new terraces, and additional rooftop accommodation.
Retaining the building’s foundations, structural frame, basement, service yard, and principal stair and lift cores changes the work required compared with demolishing the block and starting again. Selective demolition still has to be sequenced around the existing frame, with temporary support, surveys of retained elements, and new structural connections planned before openings and additional rooftop floors are formed. Planning permission establishes an authorised development envelope, not approval of every construction-stage method.
The council’s delegated report records an increase in gross internal area from 81,114 sq m to 88,048 sq m, or 6,934 sq m. Within that total, the reported office area rises from 63,028 sq m to 70,408 sq m, alongside changes to commercial accommodation on lower levels. Gross internal area is not the same measure as net lettable office space. The project also proposes two additional occupiable office floors where existing roof plant would be removed, while portions of other floorplates are cut back for daylight and external terraces.
Howells identifies the original deep floorplates and a poorly lit central atrium as constraints on the 1990s building. The proposed design cuts back selected upper floors, extends the atrium down towards ground level and towards the external façades, and creates south-facing terraces. Those changes are intended to bring daylight deeper into the occupied space and provide external amenity. They also require new interfaces between existing floor structure, glazing, weatherproofing, and revised circulation arrangements.
Howells says the existing steel frame and piled foundations are in sound condition with spare capacity for the intended additions. Its design proposes to retain all foundations and more than 70% of the superstructure. Those figures describe the planned retention strategy, not the quantity already recovered from a completed construction project. Investigations, detailed connection design, and temporary works engineering will determine how the retained members can be modified safely as demolition and new construction proceed.
New voids in floorplates and an expanded atrium can alter load paths and the way retained floors transfer lateral forces, while roof additions introduce further permanent loading and construction-stage demands. Structural design must also account for connections between new steelwork and the existing frame, as well as the sequencing needed to keep it stable while individual sections are removed. Howells identifies spare capacity as an enabling condition but has not published detailed strengthening calculations or the full temporary works method.
Replacing the façade is integral to the retrofit. Howells describes ageing precast elements and original glazing that no longer meet the project’s intended environmental and daylighting standards. The proposed ribbon-window arrangement combines glazed and solid areas, with projecting cills intended to shade windows in summer while admitting useful solar gain in colder months. As-built results will depend on glazing properties, thermal bridges, weather-tightness, and commissioning rather than the architectural concept alone.
Howells estimates that the retained construction strategy could avoid around 28,000 tonnes of carbon dioxide equivalent — approximately 350kg CO2e per square metre — compared with an equivalent new building. This is a design-stage comparison against a modelled alternative, not a measurement of carbon already saved on site. The final whole-life assessment will depend on demolition volumes, replacement materials, new structure, services, construction activity, and the assumptions used to define that alternative.
Working with Material Index, Howells has also undertaken an audit of existing components for possible salvage and reuse. A component’s suitability for reinstallation depends on its condition, dimensions, testing, certification, and the required performance in the proposed arrangement. Retaining the primary structure therefore accounts for the largest specified reuse commitment, while material recovery from demolished parts of the building will need separate evidence during delivery.
The design targets NABERS 5.5 stars and BREEAM Outstanding, but neither target should be presented as a completed-building rating. Achieving them will require the selected façade, building services, controls, and construction workmanship to perform together. The proposed atrium and external terraces also introduce interfaces for smoke management, access, rainwater control, and building-services distribution; the project documents available publicly do not establish that every detailed installation decision has been finalised.
The Cabot Square programme forms part of a wider period of renewal across established buildings in the estate, where a separate HSBC tower retrofit proposal has also progressed. The two projects concern different buildings and scopes, but both involve decisions about how much of an existing commercial structure can be adapted for new occupation rather than discarded. At 10 Cabot Square, the planning permission resolves a central consenting stage without yet confirming the physical start of work.
Howells says retrofit construction is conditional on securing both planning permission and a pre-let. The planning condition was satisfied by the 30 October decision, but a pre-let, main contractor appointment, and confirmed start date have not been established from the available project material. Canary Wharf Contractors prepared construction and logistics information for the application. The next material development will be a commercial commitment and construction programme that turn the permitted design into a deliverable site sequence.
