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Re-Waterproofing a Balcony or Roof in an Apartment: A Guide to DBPA Legislation Requirements

Understanding DBPA Legislation Requirements

The Design and Building Practitioners Act (DBPA) legislation aims to ensure that building work, including re-waterproofing, is done to a satisfactory standard. As a building owner, you're responsible for:

1. Engaging and obtaining regulated designs by a Design Practitioner to ensure the work meets the requirements of the Building Code of Australia (BCA) and relevant Australian Standards (AS 4654.1 and AS 4654.2).
2. Engaging a Building Practitioner to carry out the works.

The legislation requires that the design practitioner provides the regulated design for the class of design. There are many classes such as Structural, Facades, Architectural, Fire & Mechanical.

Balcony and roof waterproofing are required to be prepared by the following design practitioner classes:

• Architectural
• Facade
• Building Design

Step 1: Assessment and Planning

1. Identify the source of water damage or leaks.
2. Engage a professional to assess the balcony's condition and recommend the best course of action.
3. Develop a plan and budget for the re-waterproofing work.

Correctly identifying the source of the leak is critical and often overlooked. There is nothing worse than replacing an entire balcony waterproofing system only to find out the leak is related to the door or another issue.

With the correct assessment, unnecessary building works can be avoided and a practical, cost-effective solution can be provided. Water testing can be undertaken at this stage to confirm the leaks before the works are completed, so that it can be verified at the end that the work has solved the leaking issue.

Step 2: Engage a Design Practitioner

1. Ensure the design practitioner has experience in balcony and roof waterproofing.
2. Verify their compliance with DBPA legislation requirements.
3. Obtain the regulated designs.

The construction cost of the works depends heavily on the experience and practicality of the Design Practitioner.

Design practitioners often suggest ripping up all the tiles and screed and starting again, however it may not always be practical. Full demolition is costly and disruptive as the existing membrane needs to be ground out with loud machinery.

There are several ways a design practitioner can work around this while meeting Australian Standards and the Building Code. Below are several practical solutions that Excelo Consulting Engineers considers when designing external waterproofing systems:

• Installation of sheet waterproofing membrane over the existing finish with pavers on pedestals. This solution works well where there is adequate vertical termination and falls in the floor.
• Installation of sheet waterproofing membrane over a torched-on waterproofing membrane. The additional costs of mechanically grinding out the existing membrane typically outweigh the cost for the more superior sheet membrane system.
• Installation of a liquid waterproofing membrane over an existing waterproofing membrane. Depending on the condition of the membrane, this solution may offer best value.

The Design Practitioner should select compliant waterproofing membranes to AS 4654.1 only.

Step 3: Engage a Building Practitioner

1. Engage the Building Practitioner.
2. Upload the regulated design to the planning portal.
3. Carry out the work in accordance with the regulated design.

The building practitioner should review the regulated design and liaise with the design practitioner to iron out any issues. The regulated designs must then be uploaded into the planning portal and works carried out accordingly.

Step 4: Testing and Inspection

The Design Practitioner should undertake a visual inspection of the waterproofing membrane and carry out necessary checks including adequacy of:

• Waterproofing membrane dry film thickness
• Junctions, fillets and bond breakers
• Extent and termination of the membrane
• Waterstops
• Membrane is free of voids, pinholes, extrusions and contaminants

Step 5: Documentation and Compliance

1. Obtain all necessary documentation, including warranties and certification.
2. Ensure compliance with DBPA legislation requirements and relevant building codes.

Excelo Consulting Engineers provides practical and cost-effective solutions while performing peer-reviews and value engineering to achieve desired functionality at the lowest expense without sacrificing quality or performance standards.