Cassandras Trädgård

In Porvoo, Finland, two greenhouses were built for Cassandras Trädgård, one of 840 m² and one of 300 m², both founded on helical piles. The aim was to support the slab on piles, keeping concrete and reinforcement to a minimum.

In the smaller 300 m² greenhouse no concrete was used at all: the structure sits directly on the piles. Each job was finished in just two days, with one excavator and a two-person team.

The soil, mostly clay, was ideal for helical piles: the installation torque and load capacity were reached reliably without having to reach harder layers, which allowed relatively short piles. The small greenhouse used 3.0 m piles (Ø60.3 × 5.0 mm with a Ø200 mm helix); the 840 m² facility needed heavier Ø76.1 × 6.3 mm piles with a Ø250 mm helix and varying lengths.

Helical piles bring clear advantages to greenhouse construction: they avoid major excavation and, if needed, can simply be unscrewed to move or remove the structure without leaving a trace.

Two greenhouses (840 and 300 m²) · Ø60.3 and Ø76.1 mm · short piles in clay · two days per job · millimetre-level levelling