At Killara, significant structural concerns were identified in the slab-on-ground that supported three occupied levels above. Movement and cracking in the slab had raised concerns around stability, durability, and safety. With multiple levels of residents relying on the slab for support, remediation needed to be carried out with absolute precision.

The Challenge

Unlike minor crack repairs, this project dealt with a primary structural element carrying the load of three levels above. The risks were clear:

• Maintaining structural integrity throughout the works.
• Underpinning perimeter walls to prevent movement or collapse.
• Staging works in a way that kept the building safe and residents secure.

This wasn’t just about repairing concrete — it was about safeguarding the structure itself.

Approach

The remediation strategy centred on stability first. That meant careful sequencing and a staged approach to ensure no section of the building was left unsupported. Our methodology included:

• A–B staging program, dividing works into controlled zones.
• Underpinning of external perimeter walls to protect structural load paths.
• Close coordination with engineers to monitor slab behaviour during works.

Execution

1. Preparation & Investigation
   • Engineering inspections to map slab condition and load paths.
   • Site planning to sequence works while keeping the building stable.
2. A–B Staging & Underpinning
   • Works divided into alternating zones (A and B) to ensure support remained continuous.
   • Underpinning of perimeter external walls carried out before each stage to lock in stability.
3. Structural Slab Remediation
   • Breakout and removal of compromised sections.
   • Reinforcement treatment and reinstatement with high-strength repair materials.
   • Finishing and load transfer checks before progressing to next stage.

Outcome

The Killara project restored confidence in the building’s structural performance while maintaining safety throughout construction. Key results included:

• Structural Integrity Maintained – At no point was the building compromised.
• Safe Occupancy – Residents could remain in place during works.
• Extended Building Life – Slab performance reinstated for decades ahead.

Project Significance

Killara showcases how complex slab-on-ground remediation can be executed in a live environment without compromising safety. Through a disciplined A–B staging method and underpinning of load-bearing walls, the project demonstrated how engineering, planning, and execution combine to protect both people and property.

‍