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Fire Separation and Articulation Joints

Fire Separation and Articulation Joints

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NCC 2019 Volume 2 Amendment 1

Area of NCC Requirements:

  • Clause 3.7.3.2 – Fire Separation Between Class 1a Buildings
  • Performance Requirement P2.3.1


The Challenge

In townhouse and duplex-style developments, articulation joints (AJs) are often introduced to control movement and reduce cracking. But these joints can complicate compliance with the NCC’s fire separation rules.

In this case, the construction between two dwellings included articulation joints that were not fire-rated. On face value, this fell outside the Deemed-to-Satisfy (DTS) requirements, raising concerns that unprotected joints could allow fire to spread between dwellings—potentially compromising life safety and building integrity.


What This Really Means

The NCC’s fire separation provisions are designed to ensure that a fire in one dwelling does not rapidly spread to its neighbour. While DTS rules set strict conditions for wall continuity and fire resistance, real-world construction often introduces elements—like control joints—that don’t fit neatly into prescriptive requirements.

The key question isn’t whether every element is fire-rated in isolation, but whether the system as a whole provides protection consistent with the NCC’s intent: preventing fire spread long enough to allow safe evacuation and firefighting intervention.


The Solution

A performance-based fire safety assessment was carried out using expert judgement and review of the as-built construction. Key elements included:

  • A fire-rated Partiwall system separating the dwellings.
  • External wall layers of fibre cement sheeting with render and brickwork for added protection.
  • Approval by the Relevant Building Surveyor confirming compliance of primary elements.
  • Recommendation of fire-rated sealant. 

Although the articulation joints themselves were not fire-rated, their presence fell within NCC Clause 3.7.2.4(e), which allows certain small non-fire-rated openings such as control joints. With the proposed sealant treatment, the system was shown to provide equivalent—or in some respects better—fire resistance than a rigid DTS approach.


Why This Matters

The final assessment confirmed that the construction met the intent of NCC Performance Requirement P2.3.1. By demonstrating that the overall wall system provided an equivalent level of fire protection, the project achieved compliance without unnecessary redesign or cost blowouts.

This example shows the strength of performance solutions: they allow practical construction features like articulation joints to remain in place while still delivering safe, compliant fire separation. For builders, designers, and surveyors, it highlights how performance-based pathways can reconcile real-world construction practices with the strict safety intent of the NCC.


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