What's included in our Articulation Reports

You are probably reading this because your building certifier, plumber or local council has just requested an Articulation Report or Design for your plumbing and drainage application as part of your proposed building works.

The reason an Articulation Report has been request centres around the risks of building and the connected plumbing on reactive or unstable soils. Reactive or unstable soil can settle, shrink or expand over time and in certain conditions and buildings will tend to settle over time as the weight of the building compresses the underlying soils. This movement can lead to differential movement of the below ground pipework compared to the building. This movement can then lead to cracking, shearing and bending of the below ground pipework and subsequent foundation damage, contamination and environmental harm.

illustration of how settling foundations may cause problems to a buildings connected drainage system highlighting why articulation joints are so important (image source: phcppros)

To try and minimise the risk of this occurring, National Construction Code (NCC), the Plumbing and Drainage Act 2018 require a suitably qualified person to undertake an articulation design. This design should take into account soil conditions and ensure that articulation joints are provided with a suitable amount of movement to prevent failure of the below ground pipework due to soil movement.

Typical articulation joint arrangement in Class H soils (source QLD Gov: Building and Plumbing Newsflash 569)

This is what we provide in our Articulation Reports and why its necessary. Below is breakdown of what is included in a typical report.

📋 What’s Included in Our Articulation Report

1. Site-Specific Soil Assessment

   • We review the provided geotechnical site classification, to understand the soil conditions and most importantly to determine the expected ground movement that may occur between the building and ground.

2. Risk Analysis for Drainage Systems

   • We then identify how soil reactivity, settlement, trees, or fill may impact underground pipework and soil movement.

3. Design of Articulation Joints

   • Referencing and designing from the AS/NZS standards and best practice, we provide typical arrangements that set where expansion, swivel, and flexible joints are needed to absorb the predicted ground movement and soil class.

   • We covers both vertical articulation (for risers and junctions under slabs) and horizontal articulation (for branch drains and foundation exits).

4. Minimum Travel Distances

   1. We specify the minimum joint travel capacity according to AS2870 settlement ranges, with standard safety margin.

5. Pipe Lagging Thickness

   1. Pipe lagging (or sleeving) is required where pipes pass through raft or strip footings. The thickness of the lagging depends on the soil and typically varies from 20mm to 40mm. We specify the minimum required lagging thickness based on the soil conditions that will be required.

6. Construction Guidance

   • We provide guidance on placement, wrapping, grading, and support of pipework, with typical drawings to guide plumbers on correct installation.

     
     

✅ How the Report Ensures NCC and Plumbing Code Compliance

• NCC Compliance: The NCC requires sanitary drainage on reactive soils to be designed with articulation to avoid structural damage or both pipework and foundations. Our report and details are drawn directly from AS2870 (Residential Slabs and Footings) and AS/NZS 3500.2 (Plumbing and Drainage), ensuring alignment with accepted building practice.

• Plumbing & Drainage Regulation 2019: For any Class H, E or P site, an articulation design certified by a Registered Professional Engineer of Queensland (RPEQ) (or suitably qualified Hydraulic Engineer) must be submitted with the plumbing permit application. Our report provides the required information necessary to fulfil these code requirements.

• Council & Local Authority Requirements: Councils require articulation reports where reactive soils are identified. Our documentation meets these conditions, meaning faster approvals and fewer compliance issues.

If you have any questions, get in touch, and we will help where we can!