Piled Raft Underpinning

A piled underpin technique that involves severing a building from its existing foundation and providing a new internally piled raft to pickup a buildings load – often used where entire buildings require underpinning & traditional methods are not suitable or cost effective. Has the added benefit of reduced programme than traditional underpinning methods.

Construction Sequence

Internal floors are removed and site reduced to formation level (typically underside of SSL level or voidformer depending on condition and design).
Piling commences from the reduced level, typically utilizing a 2T machine we can undertake SFA (Sectional flight auger) or mini driven piles. The rigs used for this work are designed to fit through a standard 800mm doorway.
Substructure brickwork is then removed and props are introduced between the superstructure and existing foundation.
Raft construction commences, tying together the piles & our in house designed raft reinforcement. Once all steelfixing is complete the raft is poured – the raft in question additionally extends underneath all external and internal walls between the propping details.
Once cured and brickwork repairs are undertaken props are removed and the property loads the new internal piled raft.

Applications

Domestic/commercial subsidence & heave foundation failures, most applicable when entire properties require underpinning, has the addition of cost and programme benefits against traditional underpinning.