INCA EWI Case Study: Sandford Grange, Liverpool

Sandford Grange is an outstanding residential project that successfully combines heritage refurbishment with contemporary design, delivering a seamless integration between a traditional 1900s property and a modern extension. The client brief was to enhance the thermal performance of the existing building while creating a consistent, high-quality finish across both the original structure and the new build, ensuring that neither visual design nor performance was compromised.

To achieve this, JW Plastering and Rendering Ltd installed the Johnstone’s Trade Stormshield External Wall Insulation (EWI) system to the original property, significantly improving its energy efficiency. Alongside this, a high-performance full silicone render system was applied across both the insulated substrate and the new extension, ensuring a cohesive and durable façade. The use of a complementary render-only system on the extension allowed for complete visual continuity, despite the differing construction methods.

A key technical and design challenge was replicating traditional architectural detailing to preserve the building’s period character. This was successfully addressed through the use of Build-Lite moldings, which were expertly installed to form window sills, surrounds, and decorative features. Achieving the appearance of a traditionally rendered home required exceptional attention to detail and craftsmanship, particularly in ensuring that the new elements blended seamlessly with the existing structure.

The EWI System installation covered approximately 200 square metres of elevations, with a further 100 square metres installed using a Render Only System to the recently built extension.

Due to the design complexities, this project required careful planning and execution to maintain consistency in finish and alignment across both old and new surfaces. Working across differing substrates and construction types demanded a high level of technical expertise, particularly in ensuring compatibility, durability, and long-term performance of the system.

From a performance perspective, the Stormshield EWI system delivers enhanced thermal efficiency, reducing heat loss and contributing to improved energy performance of the original building by reducing the through-wall U Value to below 0.29. In addition, the full silicone render provides excellent weather resistance, breathability, and long-term durability. All essential for maintaining both appearance and function over time.

What truly sets Sandford Grange apart is the quality of the visual transformation. The completed project presents as a single, unified dwelling, with no visible distinction between the historic building and the contemporary extension. The crisp detailing, smooth render finish, and carefully replicated architectural features demonstrate a level of workmanship that goes beyond standard installation, highlighting a commitment to excellence at every stage.

The end result is a striking example of how modern EWI systems can be used not only to improve thermal performance but also to enhance and preserve architectural character. As project designer Transform Architects noted, “The transformation has been exceptional. Bringing together old and new in a way that feels completely natural while delivering a modern standard of comfort and efficiency.”

This project stands as a testament to the technical skill, precision, and design sensitivity of JW Plastering and Rendering Ltd, delivering a solution that meets both functional and aesthetic objectives to an exceptional standard.