Cantilever Beams

TECHNICAL DATA SHEET 1.3

This method stabilises existing wall foundations either internally or externally whichever the most appropriate. Two mini-piles are installed, one compression and one tension. A pocket is broken out into the existing wall and a reinforced concrete beam is cast linking the two piles.

This system is used where traditional underpinning is not appropriate due to the existing foundations being deep, or that good-bearing strata is so deep that it is uneconomical to dig. (Depths greater than 1.5m). Or needle beams cannot be used due to access constraints.

Reducing the span between cantilevers can accommodate high loads. However, the bearing capacity of the underlying strata will determine the number, diameter and spacing of piles used.

Load Capabilities using mini-piles: 

• 105mm dia SWL 60KN
• 150mm dia SWL 90KN

Piles are installed at approximately 1.0m – 1.5m centers and 1.2m apart determined by loadings. Then pockets are broken out and reinforced beams are placed to pick up the walls. Beams are usually cast alternate.

Advantages of this system are:

• Faster than traditional underpinning.
•  Access from one side only.
•  Occupants can stay in the property during construction.
• Economical at depths greater than1.5m.
• Suitable for restricted access.
• Cantilever beam constructed at a higher level if existing foundation too deep.
• High load capability.