Why Are Articulation Reports Needed in the Building Approval Process?

When building a new home or structure—especially on reactive soils—there’s more going on beneath the surface than most people realise. You may be in the situation where the building certifier or council has issued an information request to provide a certified articulation design because of the soil conditions at your site. Hopefully this article will shed some light on why an Articulation Report is needed and how it fits into the building approval process.

What Is an Articulation Report?

An Articulation Report is a specialised engineering document that sets out how underground plumbing (especially the drainage pipes) will be protected from ground movement. This is most important in areas with reactive or unstable soils, where the soil expands and contracts based on moisture levels.

Over time, this movement can place stress on your buried pipes, causing:

• Cracks or breaks in the drainage system

• Pipe misalignment or sagging (known as "ponding")

• Leaks or blockages that are costly to fix

To prevent this, an articulation report outlines:

• Where articulation joints (flexible joints) should be placed

• The type and spacing of pipe supports

• How pipework must be installed to accommodate soil movement

  
  

Why Is It Needed for Building Approval?

In Queensland (and most other Australian states), building certifiers must ensure that all plumbing systems meet the standards set out in:

• AS/NZS 3500.2 – Plumbing and Drainage: Sanitary plumbing and drainage

• The National Construction Code (NCC)

• Local council guidelines

  
  

Before a plumber can install the system—or before the certifier can sign off—the articulation requirements must be clearly documented. That’s where the articulation report comes in: it feeds into mandatory plumbing and drainage forms, providing the technical basis for how the system will remain compliant, functional, and durable.

What Plumbing & Drainage Forms Rely on the Articulation Report?

Your articulation design report is a supporting document for several important compliance submissions, such as:

• Form 1 – Compliance Assessment Application (Plumbing & Drainage)

This is submitted to council before starting work. The articulation report forms part of the design documentation attached to this application, especially for:

• Sites with reactive soil classifications (Class P, M, H, or E)

• Slabs with integrated plumbing

• Designs that must demonstrate soil movement mitigation

• Form 4 – Plumbing Compliance Certificate

After the plumbing work is complete, the licensed plumber certifies the work complies with approved plans—including any articulation measures specified in the report.

Engineering or Building Certification Documentation

Many certifiers require the articulation report as part of the foundation design and site classification response, especially when issuing Form 15 or 16 engineering certificates.

Common Triggers That Require an Articulation Report

• Reactive or clay soils (Site Class P, M, H1, H2, E)

• Slab-on-ground with in-slab pipework

• Deep sewer connections with long drainage runs

• Large structures or multi-unit dwellings with extensive plumbing

• Sites with trees or landscaping near underground drainage

  
  

Who Prepares the Report?

Articulation reports must be prepared by a qualified engineer experienced in sanitary drainage design and compliant with relevant plumbing codes. This can either be a RPEQ Civil Engineer, Hydraulic Engineer or suitably qualified Plumber (depending on the situation.