SPEEDECK proposed a CFA piled raft, integrating piling and slab into one substructure package to reduce risk, enhance coordination and accelerate build. A non-voided solution was adopted across the plots, reflecting the site’s heave assessment and allowing a faster, simpler build sequence. The approach prioritised programme certainty and minimised unnecessary excavation and handling of contaminated arisings.
Concept Design
Design Engineering
The slab was designed as a 225 mm reinforced concrete raft, sized to limit differential movement and coordinated with site levels, penetrations and edge details. Piles were 300 mm diameter CFA, designed in line with warranty requirements and achieving a maximum safe working load of 400 kN.
Pile lengths ranged from 8.0 m to 11.5 m, providing both efficiency and reliability across the site. The total raft slab area measured 986 m², enabling a single, durable substructure solution that reduced interfaces and client management time.
Construction
SPEEDECK delivered piling and raft as a single package of substructure works within a seven-week programme from start of piling to completed slabs.
This consolidated scope cut out multiple trades, simplified sequencing for underslab drainage and services, and handed back plots to SSL in a predictable window, supporting earlier starts for superstructure and services.
