Granulated cork insulation

Choose the right size for your project from four available granule size ranges: 2–4 mm, 2–9 mm, 4–8 mm, and 3–15 mm.

Expanded cork is a renewable, plant-based insulation material made from the bark of cork oak trees. It's the same natural resource traditionally used to manufacture wine bottle stoppers. Once processed, it becomes a collection of irregularly shaped, ultra-lightweight granules with a distinctive deep brown appearance.

What sets this material apart is how it's manufactured. Natural cork is exposed to high temperatures without adding chemical binders or synthetic ingredients. Heat activates suberin, a naturally occurring component of cork that helps bond the material together. As the cork expands, it develops a darker color and a lightweight, porous structure. This transformation improves its insulating performance compared with untreated cork, helping reduce heat transfer while delivering excellent sound absorption.

One of the most popular applications is residential and commercial construction. Expanded cork granules work as natural thermal and acoustic insulation, particularly in areas where traditional insulation batts or rigid foam boards are difficult to install. Because the material is loose-fill, it can flow into irregular spaces and hard-to-reach cavities. Common applications include:

• insulating attics, floors, and walls, along with narrow gaps and hard-to-access areas (the loose-fill format makes installation straightforward),
• filling interior wall cavities, insulated partitions, and double-wall assemblies,
• sloped roofs, with loose-fill insulation placed between roof rafters,
• empty spaces and concealed cavities beneath flooring systems,
• filling gaps and leveling uneven surfaces in ceilings and subfloors,
• dry screed flooring systems,
• lightweight floor assemblies.

Beyond construction projects, expanded cork granules offer plenty of creative and practical possibilities:

• as a natural substrate for exotic animal terrariums (the material is 100% natural and completely safe),
• as decorative mulch for flowers and landscaping, providing a sustainable alternative to pine bark,
• on movie sets, where the granules can resemble dirt or debris for special effects involving explosions and collapsing structures,
• in scale models and dioramas, where they create a realistic appearance of dark, natural soil.

Expanded cork can maintain its insulating performance for up to 50 years without losing effectiveness. It does not absorb moisture, support mold growth, or rot.