Project Overview

This project represents a unique and novel development in healthcare design and delivery: a fully operational outdoor Critical Care Unit (CCU) rooftop garden, purpose-built to allow critical patients to safely experience fresh air, daylight, and nature without leaving the clinical environment.

Located at King’s College Hospital in London, the 170 sqm rooftop space has been designed as an extension of the hospital’s world-class CCU, providing patients with direct access to an outdoor environment while remaining connected to life-sustaining medical equipment. Funded entirely through charitable donations, the project demonstrates how innovative design can transform patient care in a highly regulated clinical setting.

The concept was the original idea of Dr Tom Best, Critical Care Clinical Director at King’s College Hospital, who recognised the importance of caring for the mind as well as the body. Research shows that exposure to nature can reduce stress, lower blood pressure, ease delirium, and support recovery, benefits that are particularly significant for patients in critical care.

The project was led by Malcolm Hankey of Bluelight Management, with architectural input from BMJ Architects and landscape design by Professor Nigel Dunnett. Engineering and technical consultancy support was provided by WSP and Ross & Partners Ltd. Together, the team delivered a pioneering environment that meets stringent clinical, structural, fire, and accessibility requirements while offering a calm and restorative space for patients, families, and staff.

Historically, the roof remained unused due to the complexity of the structure and the challenges of installing an external amenity space on a live hospital site. This scheme has transformed that unused area into a fully compliant, functional CCU garden, setting a new benchmark for healthcare design with the potential to be replicated across NHS hospitals nationwide.

Design and Technical Approach

Given the building height, central location, and the vulnerability of the patients using the space, fire safety and regulatory compliance were non-negotiable from the outset. A fully non-combustible decking and planter support system was required, compliant with Building Regulations Approved Document B. Early design reviews ruled out composite decking options due to fire performance limitations, reinforcing the need for specialist knowledge and careful material selection.

Wallbarn became involved at an early stage through long-standing partner AB Building Products, who were supplying the fire-rated deck boards, Exadeck. Wallbarn’s role was to provide technical guidance and design support for a compliant, durable, and highly adaptable substructure solution capable of supporting a complex layout.

Exadeck boards come in standard 1.2 m lengths and, together with the MetalPad Ex pedestals, were supplied on standard Euro pallets. This provided consistency and simplified handling, storage, and movement through the hospital and up to roof level. The aluminium rails were supplied separately on larger pallets due to their 3.6 m length, but each individual rail remained lightweight enough to be handled safely by a single person, supporting an efficient and well controlled installation.

One of the key challenges was the extensive critical medical infrastructure running beneath the finished deck. This included medical gases, power, data, monitoring equipment, and service routes essential to CCU operation. The suspended decking system allowed these services to be safely accommodated below deck level while maintaining uninterrupted drainage and ventilation.

To support long-term operation and maintenance, a series of discreet access hatches were integrated into the deck at strategic locations. These hatches allow direct access to controls and critical care equipment without the need to dismantle large areas of the finished surface, ensuring both safety and practicality in a live clinical environment.

Once the decking and planter substructure design had been finalised, ISW UK Ltd were recommended to the project team as Wallbarn’s preferred installer. ISW UK Ltd are a specialist contractor with whom Wallbarn has partnered on several complex rooftop schemes during 2025, and their experience in delivering technically demanding installations made them well suited to this project.

Prior to installation, ISW UK Ltd strongly recommended a full survey of the roof area. This survey identified several discrepancies between earlier drawings and actual site conditions, including measurement variances and build-up tolerances. By resolving these issues before materials were ordered and works commenced, the team was able to produce a fully coordinated set of final drawings. Wallbarn supported this process by revising layouts, updating quantities, and reissuing accurate quotations based on confirmed dimensions. This collaborative approach helped prevent errors before they occurred, avoided unnecessary material waste, reduced the risk of on-site delays, and delivered measurable cost savings for the client.

Access, Logistics and Site Coordination

Access and logistics presented further challenges. Staircases, ground floor areas, and entry points within the hospital were temporarily dedicated to the project during construction. Working within these constraints meant that organised logistics were critical and time-sensitive, as these access routes needed to be returned to full hospital use as quickly as possible to minimise disruption to patients, staff, and visitors.

Throughout the design and delivery process, the scheme evolved in response to clinical requirements and coordination with other trades. Wallbarn joined formal discussions in February 2025, providing early-stage quotations and technical input as the layout, size, and detailing were refined. Ongoing collaboration and site coordination between June and October ensured that design changes could be accommodated without compromising compliance, buildability, or long-term performance.

The final solution incorporated a fully Class A fire-rated substructure system, including MetalPad Ex steel pedestals with Zintec 200 anti-corrosion coating, high-grade extruded aluminium rails and joists, Class A-rated fixings and connectors, and a strong, heavy-duty, non-combustible decking solution with a life expectancy of over 50 years, suitable for regulated healthcare environments. The system provides strength, precise height control, future access to services, and long-term durability.

Project Outcome

This project demonstrates what can be achieved through early collaboration, specialist technical input, and a shared commitment to improving patient care. The outdoor CCU rooftop garden at King’s College Hospital is a unique and pioneering facility that sets a new standard for critical care environments.

By successfully integrating a fully operational critical care space into an outdoor setting, the project shows how design innovation can directly support patient wellbeing without compromising safety or clinical performance. The ambition is that this model can be replicated across other NHS hospitals, creating a legacy that extends beyond this single site.

For Wallbarn, the project highlights the importance of collaboration with architects, consultants, contractors, and healthcare providers to deliver compliant, buildable solutions in the most demanding environments. It stands as a benchmark scheme that combines technical excellence with genuine social impact.