Aerial view of a modern building with curved roof, surrounded by trees and houses.

Engineered to Fall: How Gradient's Tapered System Solved a Complex Flat Roof

Detail Info
Project St Sidwell's Point Exeter
Client Exeter City Council
Contractor Massey Cladding Solutions Ltd
System Partner Triflex
Product Powerdeck F as part of a tapered Insulation system (Through Gradient UK)
System Single-Layer Tapered Insulation
Area 1,560m²
Modern glass building under a blue sky with clouds.
Aerial view of a modern building with curved roof, surrounded by trees and houses.
Flat roof installation in progress, white coating applied with rollers.
Modern glass building under a blue sky with clouds.

The Challenge

As the UK's first Passivhaus-certified leisure centre, St Sidwell's Point presented an unprecedented roofing challenge. The complex, multi-level building incorporated several roof areas, each with unique geometries, varying drainage requirements and demanding thermal performance targets.

The roof build-up needed to contribute towards exceptional levels of energy efficiency, airtightness and moisture control. At the same time, the intricate roof layouts, including boomerang-shaped sections, multiple falls, hips and valleys, required a carefully coordinated approach to ensure effective rainwater drainage without compromising the building's stringent U-value requirements.

The project team required a tapered insulation solution capable of accommodating complex falls and significant variations in insulation thickness while supporting the long-term performance objectives of this landmark sustainable development.

The Solution

Gradient UK designed and supplied a bespoke tapered insulation scheme incorporating Powerdeck F to meet the project's exacting requirements. Working closely with the wider project team, the scheme was developed to deliver both the required thermal performance and the drainage strategy necessary across the various roof areas.

The Powerdeck F solution enabled the creation of multiple falls and outlet positions throughout the complex roof design, helping to efficiently direct rainwater while maintaining the high levels of insulation. By tailoring the tapered layout to the specific geometry of each roof zone, Gradient UK provided a practical and efficient solution that simplified installation on site and ensured the design intent could be achieved.

The result was a high-performance roofing package that contributed to the delivery of one of the UK's most pioneering sustainable buildings, demonstrating how specialist tapered insulation design can play a critical role in achieving ambitious energy efficiency targets.

Project Outcome


Gradient UK's bespoke Powerdeck F tapered insulation scheme successfully met the complex drainage and thermal performance requirements of St Sidwell's Point. The solution supported the project's ambitious Passivhaus objectives while providing a practical and efficient approach to roof design and installation. As the UK's first Passivhaus leisure centre, St Sidwell's Point now serves as a leading example of sustainable construction, demonstrating the important role specialist tapered insulation design can play in achieving long-term building performance.

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