When construction, excavation, or demolition work near your property threatens your foundation’s stability, protection works underpinning safeguards your building from damage caused by your neighbour’s project. Conversely, if you’re the one planning major work, protection works ensure you meet your legal obligations to protect adjacent properties.

Through ADL Underpinning, you can connect with licensed contractors who carry out protection works for both sides of the equation — property owners defending their foundations and developers meeting their duty-of-care obligations. This page explains what protection works involve, when they’re required, and what they cost in Adelaide.

What Are Protection Works?

Protection works are structural measures taken to prevent damage to an existing building’s foundation when nearby construction activity threatens its stability. The most common trigger is excavation — for basements, swimming pools, deep footings, or service trenches — that removes soil from within the zone of influence of an adjacent foundation.

Protection works can include:

Underpinning the adjacent foundation — deepening or strengthening the existing footing so it’s no longer affected by the excavation
Shoring and retention — temporary structures that hold back the soil face during excavation to prevent it from slumping toward the adjacent property
Ground treatment — pressure grouting or resin injection to consolidate soil between the excavation and the adjacent foundation
Monitoring — crack monitors, survey points, and tiltmeters installed on the adjacent building to detect any movement during and after construction

When Are Protection Works Required?

Protection works are required whenever construction activity could affect an adjacent building’s foundation. In South Australia, this is governed by the Building Code, the Development Act, and common law duty of support.

Specific triggers include:

Excavation within the zone of influence — generally defined as a 45-degree angle drawn from the base of the adjacent footing. Any excavation within this zone may remove support from the neighbouring foundation
Vibration-generating activities — pile driving, rock breaking, compaction, and heavy machinery operation near existing buildings
Dewatering — pumping groundwater from an excavation can draw water from beneath adjacent foundations, causing consolidation and settlement
Demolition — removing a building that shares a wall or has interconnected foundations with the adjacent property

Legal Obligations in Adelaide

If you’re the developer or builder undertaking the work, your obligations include:

Duty of support — you must not remove the natural support of adjacent land. If your work causes damage, you’re liable
Notice requirements — you must notify adjacent owners before commencing work that could affect their property
Pre-condition report — documenting the existing condition of adjacent buildings before work starts. This protects both parties
Engineering assessment — a structural engineer must assess the impact of your work on adjacent foundations and specify any protection works needed
Insurance — adequate public liability insurance and, in some cases, specific construction works insurance

If you’re the adjacent property owner whose building is at risk, your rights include being notified, having your property surveyed before work starts, and holding the developer responsible for any damage.

Common Adelaide Scenarios

New Townhouse Developments

Adelaide is seeing significant infill development — older homes demolished and replaced with two or three townhouses. The new buildings often have deeper footings than the originals, and excavation for the new slabs can undermine adjacent properties. This is particularly common in Prospect, Norwood, Unley, and Charles Sturt.

Basement Construction

Basement excavation is the highest-risk scenario for adjacent properties. Excavating 3+ metres below surface level removes significant soil support. Protection works are almost always required.

Swimming Pool Excavation

A pool hole excavated close to a boundary can undermine the adjacent property’s foundation or retaining walls. The risk increases with pool depth and proximity to the boundary.

Retaining Wall Construction

Excavating for a new retaining wall near the boundary temporarily removes lateral support from the adjacent soil, potentially affecting nearby foundations.

Our Protection Works Process

Risk assessment — we evaluate the proposed construction activity, the proximity to adjacent buildings, soil conditions, and the depth and type of adjacent foundations
Pre-condition survey — we document the existing condition of all potentially affected buildings: photographs, crack widths, floor levels, and structural observations. This becomes the baseline for any future damage assessment
Engineering design — a structural engineer designs the protection works: method, extent, depth, and sequencing. The design considers both the temporary construction phase and the permanent condition
Underpinning installation — protection underpinning is completed before the triggering excavation begins. Depending on the situation, our partner contractors use screw piles, mass concrete, mini piles, or micropiles
Monitoring during construction — we monitor the protected buildings throughout the adjacent construction for any signs of movement
Certification — the engineer certifies the protection works, and a final condition survey confirms no damage has occurred

Protection Works Costs

Costs vary based on the extent of protection required:

Minor protection (shallow excavation, one wall, close monitoring): $8,000–$20,000
Standard protection (townhouse development, adjacent property underpinning): $20,000–$50,000
Major protection (basement excavation, multiple adjacent properties): $50,000–$120,000+

Note: when you’re the developer, protection works costs are your responsibility. They should be included in the project budget from the outset.

Your Property Is at Risk — What Should You Do?

If a neighbour has started (or is planning) construction that concerns you:

Request a copy of their development approval and engineering plans
Insist on a pre-condition survey of your property before their work starts
Ask what protection works they’ve specified and who will carry them out
Document any existing damage with dated photographs
Contact us for independent advice — email chris@adlunderpinning.com

Acting before the excavation starts is critical. Once the soil has been removed and damage has occurred, remediation is far more expensive and complex than prevention.

Planning Work That Needs Protection?

If you’re the developer or builder, we can design and install protection works that meet your engineering requirements and keep the project moving. Email chris@adlunderpinning.com with project details and we’ll provide a scope and quote for the protection works component.

Protection Works Underpinning Adelaide