Wooden foundation pile

A driven softwood pile (pine/spruce) that carries a building on soft, waterlogged ground. Below the groundwater table it does not rot, so the biogenic carbon in the timber stays locked away for centuries — the Amsterdam "underground forest". Solid timber stores ~0.85 t CO2 per m³; a single house foundation of 30–50 piles locks in the order of 25–35 tonnes of CO2, an order of magnitude more than the building's insulation.