Overcoming complex technical challenges at Tottenham Hale

Sitting opposite Tottenham Hale station, the Welbourne development is a key component of the ‘Heart of Hale’ initiative, led by United Living and the London Borough of Haringey. Designed by Pollard Thomas Edwards and CZWG Architects, the scheme provided 131 new council homes and a two-storey health centre serving over 20,000 local residents. As a flagship project combining high-density housing, essential infrastructure and ambitious environmental standards, Welbourne demanded innovative solutions at every level – and that included the design and integration of a reliable, high-performance blue/green roof.

Blue roof technology was identified as a critical part of the SuDS (Sustainable Drainage Systems) strategy for the development. In response, Proteus delivered a technically demanding, multi-functional blue/green roof system capable of supporting water attenuation, as well as providing integrated biodiversity, recreational landscaping and energy-efficient insulation.

Design challenges

A central podium deck within the development presented a unique engineering challenge. Originally designed with zero falls, the planning revisions and insurance regulations were later changed to incorporate a minimum 1:80 slope, prompting a major redesign of the blue roof system.

The original blue roof specification could not meet the new flow rates and attenuation volume without breaching the finished floor levels. Moreover, it lacked a compliant exceedance overflow strategy, as per EN 12056 standards. In response, Proteus Waterproofing collaborated with its systems partner to develop a bespoke tapered blue roof system. This allowed the entire system to incrementally step down from 285mm to 60mm over a 30m span - maintaining both attenuation volume and regulatory compliance.

Further challenges included the need to integrate multiple surface finishes and avoid breaches at door thresholds. Accommodating water flow from upper-level blue/green roofs and designing structural overflow systems for emergency drainage also had to be incorporated. Through precise mapping and system mock-ups, the team ensured the podium remained level for usability while concealing the necessary attenuation build-up.

Expert installation

The complexity of the design required meticulous workmanship. The Proteus Hot Melt® system provided the robust primary waterproofing layer, supported by XPS Plus insulation and a patented blue roof system, which is part of the complete Attenu8® system by Proteus. Every element was tested and trialled through site demonstrations before full installation.
Custom edge detailing was used to prevent ponding at perimeters; and differing substrate mixes were used for varied plant species depending on sun and wind exposure. The Proteus technical team remained on-site for routine inspections, ensuring that each stage met their stringent installation and quality standards.

With the site located in a densely populated urban area, delivery logistics were particularly challenging. Proteus Waterproofing and Complete Waterproofing Services Ltd coordinated material deliveries during off-peak hours, using FORS Gold-accredited vehicles to reduce environmental and traffic impact.

Work sequencing was also carefully planned to minimise congestion; and flexible timelines accounted for weather delays. Weekly meetings and open channels with the client and contractors ensured transparency, responsiveness and strict adherence to the project timeline.

The Welbourne Blue Roof project is a good example of collaborative design innovation, sustainable construction and technical excellence. It demonstrates how strategic partnerships could overcome complex design constraints to deliver a resilient, beautiful and functional roofing solution.