A recent LinkedIn post by Mark Alexander, CEO of the Association of Hydraulic Services Consultants of Australia (Victoria), highlighted another substantial building defect claim involving more than 350 balconies.

While the specifics of the project remain subject to investigation, the post serves as an important reminder of a broader issue facing the construction industry: balcony failures continue to occur at significant scale, often years after completion.

For building owners, developers, contractors, and consultants alike, the consequences can be severe. Remediation works may involve waterproofing replacement, finishes removal, scaffolding, structural modifications, drainage upgrades, and extensive disruption to occupants. In many cases, rectification costs can far exceed the original construction cost of the balcony itself.

Quality Is Built Into the Design Process

Many construction defects are not the result of a single mistake. Instead, they often arise through a combination of factors:

• Incomplete design documentation
• Poor coordination between disciplines
• Site construction variations
• Inadequate inspection and quality assurance
• Insufficient consideration of maintenance and overflow conditions

Balconies are particularly vulnerable because they involve multiple systems working together. Waterproofing, structure, finishes, hydraulic drainage, overflow provisions, and threshold and accessibility requirements must all perform as a coordinated whole. When one element does not perform as intended, the entire system can be compromised.

This is precisely why the involvement of a qualified hydraulic engineer from early in the design process is so important. Drainage capacity, overflow provisions, surface gradients, and interface details between trades are not afterthoughts — they are fundamental to whether a balcony performs over its intended life.

Engineering Is More Than Compliance

Meeting minimum code requirements is essential, but quality engineering requires more than simply satisfying compliance obligations.

Good engineering design considers:

• Constructability — can the design actually be built as documented?
• Durability — will the system perform under real-world conditions over time?
• Maintenance requirements — can the system be accessed, inspected, and maintained?
• Future access — are maintenance points accessible without major disruption?
• Failure scenarios — what happens if a component underperforms or fails?
• Long-term building performance — how does the design hold up across the full lifecycle of the asset?

For hydraulic systems, this includes careful consideration of drainage capacity, overflow provisions, surface gradients, water ingress pathways, and interface details between trades. The smallest overlooked detail — a missing overflow outlet, an inadequate fall, a poorly detailed threshold — can become a significant and expensive problem years later.

The same principle applies across all engineering disciplines. Structural engineers must consider how loads are transferred through balcony connections. Civil engineers must account for stormwater and site drainage that interacts with the building envelope. When these disciplines are coordinated from the outset, the risk of system failure is substantially reduced.

The Value of Independent Design Reviews

One of the most effective risk management tools available on complex projects is independent review and coordination.

Independent review processes can help identify:

• Design inconsistencies
• Coordination clashes between disciplines
• Missing or incomplete documentation
• Constructability concerns
• Maintenance access issues

— before they become costly defects.

The cost of additional review during design is often insignificant when compared with the potential cost of rectification after construction. A thorough review at documentation stage is far less disruptive than scaffolding, demolition, and remediation works on an occupied building.

Multi-discipline consultancies are particularly well placed to support this process. When hydraulic, structural, civil, mechanical, and fire services engineers are working from the same documentation and communicating directly, coordination gaps are identified and resolved before they reach the construction site.

Waterproofing, Drainage, and the Interface Between Trades

Balcony failures frequently occur at the interface between trades — where the waterproofing membrane meets the structural slab, where the drainage outlet penetrates the membrane, or where the threshold detail must balance water exclusion with accessibility requirements.

These interfaces require clear documentation, clear responsibility, and clear inspection protocols. When documentation is ambiguous or coordination is poor, the risk of a defect at these critical junctions increases significantly.

From a hydraulic engineering perspective, key considerations include:

• Drainage capacity — is the outlet sized to handle the design rainfall intensity without ponding?
• Overflow provisions — is there a secondary overflow path if the primary drain becomes blocked?
• Surface gradients — are falls sufficient to direct water to the outlet without pooling?
• Water ingress pathways — have all potential entry points been identified and addressed in the design?
• Interface details — are the connections between the drainage system and the waterproofing membrane clearly documented and coordinated with the waterproofing specification?

These are not complex questions, but they require deliberate attention. When they are not addressed at design stage, they tend to surface — sometimes literally — after construction is complete.

A Focus on Long-Term Outcomes

At MAS Consulting Engineers, we believe successful engineering is measured not only by project completion, but by long-term building performance.

Whether delivering hydraulic, fire services, civil, structural, or multi-discipline engineering services, our objective is to produce coordinated, practical, and durable designs that support the entire lifecycle of the asset.

As the industry continues to learn from past building failures, the focus should remain on quality design, quality construction, and quality assurance. Every project stakeholder benefits when buildings perform as intended for the people who live, work, and invest in them.

If you are working on a project that involves balconies, podium decks, or other waterproofed external areas and would like to discuss how MAS can support the hydraulic and drainage design, we would welcome the conversation.

---

MAS Consulting Engineers is a multi-discipline engineering consultancy operating across QLD, NSW, VIC, SA, and WA. Our services include Building Hydraulics, Electrical Engineering, Mechanical Engineering, Civil Engineering, Structural Engineering, Fire Services Engineering, Geotechnical Engineering, Flood & Stormwater Management, and Wastewater Engineering.