Ide Hill, Sevenoaks, Kent
Products Used
Ide Hill development in Kent demonstrates how natural slate roofing can play a critical role in delivering world-class energy efficiency while maintaining timeless architectural appeal. Designed and constructed to rigorous Passivhaus standards, the project required every element of the building envelope to contribute to thermal performance, airtightness, durability and sustainability.
At the heart of the roofing specification was SSQ Del Carmen Ultra slate, paired with an integrated Riverstone Ultra Phyllite ridge system. Selected for its exceptional quality, longevity and aesthetic consistency, the natural slate roof provides a high-performance solution that supports the stringent demands of low-energy building design.
How to achieve roof build-up with natural slate for Passivhaus construction
Natural slate is increasingly recognised as an ideal roofing material for Passivhaus projects due to its ability to contribute to a stable and efficient building envelope. At the Ide Hill project, the slate roof was installed over a highly insulated construction incorporating a 100mm solid fibre insulation slab. The ventilated roof build-up creates a continuous air gap, helping to reduce wind loading, minimise thermal bridging and improve overall thermal stability. These characteristics are essential in achieving the ultra-low energy requirements associated with Passivhaus construction.
SSQ Del Carmen with PV panels
The results speak for themselves. The completed property achieved an outstanding airtightness rating of just 0.205 h⁻¹ @ 50Pa, placing it among the highest-performing residential properties in the UK. This exceptional level of performance highlights the importance of combining advanced construction methods with carefully selected natural roofing materials.
Installation quality was equally important. The Red Wing Roofing Ltd team used counter battens and slating battens to accommodate the insulated roof build-up while maintaining correct ventilation and fixing practices. String lines were employed throughout the installation to ensure perfectly aligned slate courses and prevent diagonal drift across the roof slopes. Challenging details, including a central gutter arrangement, required individually cut slates to create a precise, weatherproof finish without compromising the clean architectural appearance of the roof.
Slate for environmentally conscious construction
Beyond its technical performance, the slate specification delivers significant sustainability benefits. Natural slate offers an exceptionally long service life, low embodied carbon and zero chemical emissions, making it a responsible choice for environmentally conscious construction. Combined with its durability and minimal maintenance requirements, it provides a roofing solution capable of performing for generations.
The Ide Hill Passivhaus project showcases how premium natural slate roofing can support the delivery of ultra-efficient homes. By combining the proven performance of SSQ Del Carmen Ultra slate with meticulous installation and high-performance insulation, the project sets a benchmark for sustainable residential construction, energy-efficient roofing and Passivhaus design.
