We are inviting clients and architects to witness the hidden engineering that transforms a cold stone ruin into a warm, breathable, modern home.

We are delighted to announce that our latest show-house—a deep retrofit of a historic stone building—is now open for viewing. However, we should be clear from the outset: this building will never be “finished” in the traditional sense.

A Permanent Living Laboratory

While the performance shell is complete, we have intentionally designated this site as a permanent R&D facility for humidity and water management systems. It is a “living laboratory” where we monitor the long-term relationship between ancient masonry and modern science.

By visiting now, you aren’t just seeing a construction site; you are witnessing the “guts” of a working laboratory. Usually, by the time a show house opens, the walls are skimmed, and the engineering is hidden. Right now, you can get under the skin of the building to see the insulation strategies that are typically invisible.

The Vision: Heritage Without Compromise

Restoring an old stone barn does not mean you have to live in a cold, damp, or dark house. We have taken a traditional stone structure and transformed it into a highly insulated contemporary home that follows Passive House principles and meets all NZEB (Near Zero Energy Building) guidelines.

To achieve this, we have increased the building’s height using a Steico I-joist system and clad the upper section with a modern cement board designed to emulate the charm of natural wood.

In the spirit of a “Living Laboratory,” we must be candid: this specific aesthetic finish has not fully met our expectations, and we intend to replace it. However, the aesthetic is secondary to the technical triumph: we have proven that it is entirely possible to insulate old stone walls in a breathable way that meets—and exceeds—modern insulation standards. This project proves you can achieve a superior energy rating without sacrificing the character of a historic building.

The Challenge: Warmth Without Damp

The greatest concern with old stone buildings is damp. If you trap moisture behind synthetic foam, you risk mould and structural decay. Historic buildings need to “breathe.”

To solve this, we have used a combination of natural, vapour-permeable materials that allow moisture to escape while keeping the heat firmly inside:

• The Stone Walls (Diathonite): On the solid masonry, we have used Diathonite—a cork-based, lime thermal plaster. Sprayed on like a “thermal jacket,” it fills every crack and void in the stone, eliminating cold bridges and allowing the wall to regulate humidity naturally.

• The Roof & Upper Frame (Steico): The Steico rigid wood fibre used in the roof and upper walls provides exceptional insulation against the winter cold, while its high thermal mass prevents the building from overheating in the summer.

The Result: 20°C All Year Round

Thanks to the insulation and airtight detailing, the building can maintain a constant 20°C year-round, with almost no need for auxiliary heating. It is a future-proofed home with negligible running costs.

Fire Safety: Resilience in a Changing Climate

We cannot ignore our changing climate. Fire risk is increasing, and we have built this home with resilience in mind, incorporating lessons learned from the devastating wildfires in California.

While the stone walls offer natural protection, we have ensured the upper external skin is built using fire-rated materials to create a non-combustible envelope. Crucially, we have addressed “ember attack” by installing spark-arresting mesh to seal all ventilation gaps, preventing wind-blown embers from entering the wall fabric.

Rainwater & Snow Management: The Roof Strategy

A key part of our ongoing research involves rainwater collection and drainage systems that remain fully functional in extreme conditions, particularly during heavy snow.

For this reason, we have opted for a metal roof while our testing of these guttering and collection systems is ongoing. This allows us to monitor water flow and structural performance under various weather conditions with high precision. Once we have gathered sufficient data and perfected the system’s integration, we may transition the roof to traditional slate to match the building’s historic aesthetic, but we are still undecided, as it’s only a test house, and we are amazed at how well the metal roof is performing and is not noisy inside with the high levels of insulation. 

Ongoing Product Testing

Over the coming years, the house will serve as a live environment for monitoring:

• Hygroscopic Performance: Real-time testing of how our lime and cork render handle internal humidity.

• Vapour-Permeable Finishes: Experimenting with Polished Diathonite and Natural Clay Plasters.

• Water Management Trials: Testing new techniques for adhesion, durability, and moisture control.

Why visit now? We believe in absolute transparency. Our site lead, Jose, is currently tied up, as we always prioritise our clients’ deadlines. We are finishing the external pointing and interior transitions in deliberate phases. This gives you a rare opportunity to see the technology in its raw state before the final finishes are applied.

Experience the Future of Heritage Retrofit

Don’t miss this opportunity to see the technology before the final pointing and plaster hides it forever. Contact Claire via the online form to organise a viewing.

Inquiries?