Forensic Investigation of Systemic Cladding Failure in New Zealand Schools

The systemic cladding failure in New Zealand schools has been a significant issue, drawing attention to the importance of understanding moisture management in building enclosures. The seven-year forensic investigation provided crucial insights into this problem by implementing various advanced monitoring techniques and analytical models. For insights on New Zealand School Construction Litigation and tools for analyzing radiata pine projects, watch Brian Hubbs’ presentation from the Zac Facades Conference in Brisbane.

Key Aspects of the Investigation:

In-Situ Monitoring:
The study involved monitoring four schools' as-built conditions over several years. This included air and water testing using SMT sensors and a range of other devices such as driving rain gauges, moisture content sensors, relative humidity sensors, condensation sensors, and temperature sensors. These tools helped track the moisture dynamics within the building assemblies, enhancing the understanding of when and where moisture issues arose.
Test Hut Construction:
A controlled test hut was built to simulate various assembly design or detailing variables. This experimental setup allowed for side-by-side comparisons in performance under controlled conditions. The test hut mimicked the school's construction features like cladding, windows, flashing, roofs, and base-of-wall details, equipped with similar sensors and data loggers.
Hygrothermal Modeling:
The research team developed 1D and 2D hygrothermal models to predict moisture behavior within building assemblies. These models were calibrated for accuracy and could be extrapolated to other school sites, offering a predictive tool for assessing potential moisture issues in similar buildings.
Laboratory Testing:
Comprehensive lab tests were conducted to create material-specific mold and rot indices, providing predictions for "time to visible" mold and rot. This work contributed to the development of a New Zealand code risk index to highlight variables that contribute to cladding failure.

Outcomes and Applications:

The investigation's results have far-reaching implications, offering a scientific basis for predicting and preventing cladding failures in educational and other types of buildings. By understanding the dynamics of moisture absorption and retention in building materials, stakeholders can improve design and construction practices, potentially reducing the incidence of such failures in the future.

Legal and Industry Impact:

Significant legal actions and settlements, as reported in various sources, underscore the gravity of this issue. The case emphasized the need for robust building codes and regulations, which factor in observed performance issues with specific materials and construction practices.

The understanding gained from this investigation aids in refining building codes, designing better moisture management systems, and addressing existing structure deficiencies to enhance the durability and safety of buildings across New Zealand and potentially in other regions facing similar issues.

Additionally, you can explore the research publication titled "Forensic Engineering Practice Lessons - A Case Study of Cladding Failures in New Zealand" for a deeper understanding of the topic: Read the Publication.