25 Moorgate, London

Working in partnership with an Approved Contractor, Essential Building Services, Proteus provided a fully integrated waterproofing design and system solution for this complex refurbishment, which achieved BREEAM ‘Outstanding’ and WELL ‘Platinum’ certifications.

The redevelopment of 25 Moorgate represented a significant evolution of an existing building into a modern,low-carbon workspace. The scheme included the addition of two new upper floors, alongside a series of terraces and a standout 8th-floor communal space featuring over 1,700 sq. ft of wrap-around external area.

At roof level, the project required the integration of new and existing structures, presenting a series of technical and logistical challenges. These included low upstands, complex interfaces with cladding systems and working within confined rooftop environments alongside multiple trades.

Design-Led Waterproofing Approach

Proteus led the waterproofing design strategy, delivering a robust system across both exposed and buried roof areas, including the critical main roof level.

A comprehensive system build-up was specified, incorporating Cold Melt® technology alongside highperformance insulation, vapour control layers and advanced waterproofing components. The system was designed to provide long-term durability and water resistance, as well as support the building’s wider environmental objectives.

To ensure performance integrity, an Electronic Leak Detection (ELD) test was carried out, with all results verified and signed off by the Proteus Technical Team prior to final finishes. This formed a key part of the guarantee process and ensured complete confidence in the system’s long-term performance.

Overcoming Technical and Logistical Challenges

25 Moorgate required a particularly high level of coordination and adaptability. The integration of new and existing roof structures demanded precise detailing, especially in older areas of the roof where there were uneven surfaces, backfalls and restricted detailing zones. Midway through the programme, a change in main contractor introduced a new design team, requiring rapid reassessment and adaptation of waterproofing details. Proteus responded quickly, revising specifications and maintaining programme momentum without compromising quality.

Logistically, the site presented significant constraints. Materials were lifted via crane under tightly controlled road closures, and transported through the building using internal hoists. Working areas were often limited, particularly on narrow wrap-around terraces, requiring careful sequencing and coordination with other trades.

Excellence in Workmanship and Delivery

Essential Building Services demonstrated exceptional workmanship throughout the project, particularly in managing complex detailing around upstands, balustrades and interfaces with other building elements.

Protective measures were implemented to safeguard completed waterproofing areas from damage during ongoing works, reducing the need for rework and maintaining system integrity.

Most especially, the team’s ability to adapt to evolving site conditions, including accommodating changes from other trades, ensured that the project remained on track despite its complexity.

Performance, Sustainability and Long-Term Value

The completed roofing system delivered a high level of thermal performance, achieving a U-value of 0.12 W/m²K through a tapered insulation design. This significantly reduced heat loss and supported the building’s low-carbon objectives.

Proteus systems were selected not only for their performance, but also for their contribution to sustainable construction. Efficient material use, reduced waste and responsible logistics all formed part of the delivery strategy.

The 25 Moorgate project demonstrated how complex refurbishment schemes can successfully integrate highperformance waterproofing within a wider sustainability agenda.

Through technical expertise, collaborative working and a commitment to quality, Proteus Waterproofing delivered a future-proof roofing solution that supported both the building’s performance and its long-term value.