INCA Case Study: Whiteway House, Marlborough​

Project Detail

Two Homes, One Vision: A Unified Exterior with Hidden Performance
This unique External Wall Insulation project stands as a shining example of how thoughtful detailing, system flexibility, and skilled installation can bring cohesion and efficiency to homes of varying age and construction. Delivered by Emma Kirby Design and specified by PRB, the scheme blends traditional and modern elements into a single, elegant façade, all without compromising on thermal performance or design integrity.

Material Harmony: Matching the Fabric to the Function
The property features two distinct structural components, an older building requiring breathability and a newer extension built to modern specifications. With this in mind, the EWI strategy was split: 90mm mineral wool was applied to the original structure to maintain vapor permeability and enhance acoustic properties, while 90mm EPS was chosen for the newer extension, offering lightweight, cost-effective thermal insulation.

Despite the difference in substrates and insulation materials, the entire structure is flawlessly tied together using PRB’s premium Thermolook Blanc de La Cote render system. This finish not only ensures visual consistency but adds a coastal-inspired charm, durable enough to stand the test of time and weather.

A Unified Finish with Performance at Its Core
One of the most impressive elements of the project is how the external envelope now reads as one cohesive whole. From the street, you would never guess that two different insulation systems are working in tandem beneath the surface. The Blanc de La Cote topcoat brings a timeless, clean finish that adds character and kerb appeal, while providing critical protection to the insulation layer beneath.

Thermal comfort and energy savings were key drivers of this retrofit, and the EWI system delivered on both fronts. The home now boasts a dramatically improved U-value across both construction types, with the 90mm mineral wool-insulated elevations achieving 0.32 W/m²K and the 90mm EPS-insulated areas reaching an impressive 0.28 W/m²K. These figures represent a substantial upgrade from the original thermal performance, helping to cut energy bills, reduce environmental impact, and ensure consistent comfort throughout the year.

The Installer’s Perspective
Emma Kirby Design approached the project with the precision and creativity it deserved. The team ensured meticulous installation across both fabric types, with attention paid to every corner, edge, and junction to maintain thermal continuity and flawless detailing. The collaboration with PRB ensured a specification that was both technically sound and visually striking.

A Showcase of Smarter Retrofitting
This project demonstrates how combining the right materials with skilled craftsmanship can bring performance parity to diverse building elements without sacrificing style. It’s a model for future-facing retrofit work, particularly in homes that combine different construction periods.

It’s more than an insulation job, it’s a seamless architectural upgrade that shows how old and new can live side by side, not just aesthetically, but thermally and functionally.