Use case
Thermal insulation
Low-lambda cork granules and boards that hold their performance over decades.
Synthetic insulation drifts. Blowing-agent gases leak from closed-cell foams; fibre batts settle and leave thermal bridges. Cork has no gas to lose — its cells are sealed pockets of air bound by suberin walls that have been stable for the lifespan of the cork oak.
The hidden failure mode of synthetic insulation is lambda drift. A foam board rated at 0.035 W/(m·K) on day one can creep to 0.045 within a decade as the blowing-agent gases diffuse out of the cells. The difference sounds small but it translates to measurable energy loss across a building's life.
Cork does not drift because its thermal performance is structural, not chemical. The air pockets are sealed by suberin — a natural polymer that does not degrade under normal building conditions. Lambda values of 0.038–0.045 W/(m·K) are delivered by the geometry of the cells, not by a gas that will eventually escape.
For pourable applications, coarse cork grain at 70 kg/m³ fills cavities and voids that rigid boards cannot reach. For board applications, agglomerated cork panels at 180–280 kg/m³ deliver the same lambda with the rigidity needed for framed assemblies.
Why cork works
The material advantage.
- Lambda values of 0.038–0.045 W/(m·K) with no drift over time.
- No synthetic blowing agents — performance is structural, not chemical.
- Carbon-negative cradle-to-gate when traced to Portuguese montado.
Products for this use