The Cladding, Insulation, and Flooring of This London Loft Extension Are All Made of Cork

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Project Details:

Location: London, United Kingdom

Architect: Office S&M / @officesandm

Footprint: 1,290 square feet

Builder: Square Mile Builders

Structural Engineer: Foster Structures

Photographer: French+Tye / @frenchandtye

From the Architect: "Long-time Walthamstow residents Quentin and Anaïs, originally from France, commissioned Office S&M Architects to refurbish and extend their North London home. Their brief was simple yet bold: create a loft extension unlike any other, one that challenges convention and celebrates sustainability through creativity. Before the renovation, the house had not been refurbished for decades. It was dark, damp, and affected by mold. Determined to transform it, Quentin and Anaïs wanted a design that placed sustainability at the heart of the project. The loft extension marks the first phase of a larger master plan that includes a full retrofit, external insulation, and a ground floor extension.

"Cork was chosen for its remarkable environmental and material properties. Harvested from the bark of cork oak trees without felling them, cork sequesters carbon, and is both biodegradable and recyclable. It offers excellent thermal and acoustic insulation, is lightweight, and requires minimal maintenance. Its harvesting process is efficient and regenerative: the bark is stripped, the tree continues to absorb CO₂, and the entire material is used. The sheets are formed without synthetic binders, relying instead on the cork’s natural sap to hold the granules together.

"In this project, cork has been used as external cladding, insulation, flooring, and even as aggregate in the render. Its lightweight properties made it ideal for a loft, where materials must be transported and supported by existing Victorian foundations. Cork’s durability, resistance to moisture and mold, and longevity make it a future-ready building material. Like many natural materials, cork evolves over time. Exposure to sunlight, wind, and rain shifts its color and texture. Through sampling and prototyping with Materials Assemble, we choreographed this natural transformation, creating a facade that gradually changes. Panels treated with different UV protections fade at varying rates, revealing a subtle pattern inspired by World War II dazzle ships.

"While most lofts blend quietly into their roofs, this project celebrates contrast. The extension respects the proportions of the Victorian host while asserting its own identity. Initially, the cork’s deep brown tones echo the surrounding slate roofs, but as it weathers, a pattern emerges, harmonizing with the brick and mortar below.

"Inside, the two tones of cork continue through the bedroom and stairwell, forming dynamic stripes across the floor. Yellow accents—a nod to the clients’ French heritage—highlight rainwater goods and window frames, echoing the cheerful details of rural French architecture. Inside, yellow guides the eye through the stairwell and brightens the core of the home, culminating in pendant lights that cascade through the house like a chandelier.

"Film is a shared passion for Quentin and Anaïs, and this influence appears throughout. A rectangular window frames the garden like a cinema screen, while a circular window in the shower offers playful, porthole-like reflections. Above the shower, a frameless roof light opens to the sky—the ‘infinity shower.’ Cork Loft demonstrates how versatile cork can be, and how sustainability can be imaginative, beautiful, and bold."