Perhaps it’s a feature of our Number 8 wire mentality, but it’s a common occurrence for Kiwi property owners to make adaptations and enhancements to their buildings. For residential properties, this might take the form of adding a deck or patio, converting a garage into a living space or adding a sunroom or conservatory. In the commercial sector, its updating fit-outs and refurbishments to suit new tenants or modernise facilities, or adding accessibility features, mezzanine floors or transforming a building into multi-unit developments. It’s also common with New Zealand schools to see an expansion in stages, with some of the most common additions being modular classrooms to manage roll growth, specialist learning spaces, and two-or three storey blocks added where land is tight.
Improvements can of course add significant value and utility, but they also introduce new risks, and complexities. Issues such as non-compliances, leaks, structural movement, and material failure can arise in any type of extension or alteration, often with costly consequences if left unchecked.
Building surveyors are the professionals who help navigate these challenges. Our expertise lies in identifying problems early, diagnosing root causes, and recommending practical solutions that safeguard both residential and commercial aspects.
In this article, we’ll explore the investigative process used by surveyors, in conversation with Graeme Calvert, Registered Building Surveyor with 40 years’ experience in the industry, and Technical Director here at Maynard Marks, based in Ōtautahi Christchurch. We’ll talk about the approach surveyors use to uncover hidden issues, drawing on real-world experience and industry best practice.
The Role of the Building Surveyor
Building surveyors play a crucial role in maintaining the health of both residential and commercial buildings. Acting as both investigator and as advisor, building surveyors assess the condition of buildings, diagnose defects, and identify potential risks before they escalate. The work we do is grounded in impartiality, technical rigour and adherence to New Zealand codes and standards.
As Graeme says “it’s a common analogy and an accurate one; every building tells a story. Our role as Building Surveyor, is to ‘read’ this story, and help owners make informed decisions”
First Signs of Trouble
Graeme has seen first-hand how adaptations and alterations can both enhance, and challenge New Zealand buildings. The most well-intentioned changes can create unforeseen challenges, making expert assessment essential for long-term building health. Often, that first call to us is triggered when something isn’t quite right with a property, whether it’s a persistent leak, visible damage, or some other change in how the building performs. Owners may notice damp patches, mould, cracks, or other signs that prompt concern, and that’s when a professional assessment becomes essential.
Once a surveyor is engaged, Graeme describes the rigorous process that follows. He says, “the approach we take will be tailored to each building’s unique circumstances, but it is always highly methodical.”
1. Visual Survey
We will first complete a comprehensive visual inspection, both inside and out. We look for tell-tale signs: staining, mould, cracks, or construction details that don’t match original plans or manufacturers technical literature. Our surveyor will also review council property files and building documentation to understand the building’s history and any previous alterations.
2. Moisture Testing
In situations where there are concerns over leaks, we may use specialist equipment to measure moisture levels within walls, floors, and ceilings, with the tests used being dependent on the materials present in that built environment.
A hygrometer test measures the moisture content in masonry, for example concrete floors or wall screeds. It uses a hygrometer device to monitor the relative humidity within a sealed chamber. A hygrometer is often used to check that a concrete floor has dried to an appropriate level before laying flooring, preventing issues like adhesive failure, mould growth or others defects and damage caused by excess moisture. Read more about Hygrometer tests here.
For timber, and other porous materials, we might first consider using capacitance (surface non-invasive) moisture meters, which detect moisture through an electromagnetic field without penetrating the surface. These are ideal for finished surfaces or when we need to scan large areas quickly, without causing damage. Where direct contact is possible, we may use resistance (invasive probe) moisture metres, which measure electrical resistance between two pins inserted into the material. This method provides indicative readings of internal moisture, but leave small pinholes so is best suited for areas where minor surface damage is acceptable. In practice, both types can be used together: capacitance meters for initial non-invasive surveys and resistance meters for targeted, deeper checks where confirmation is needed. Both can help us to identify hidden leaks, or areas of persistent dampness that may not be visible on the surface.
3. Water and Dye Testing
Water and dye testing is a highly effective method for identifying water ingress, particularly in building elements such as roofs, façades, and windows. Recently, Graeme investigated a residential conservatory extension where persistent leaks were causing concern for the owners. After an initial visual survey revealed signs of moisture and staining, he determined that further testing was required.
To simulate rainfall and trace the path of water, Graeme and the team carried out controlled spray tests. In this process, brightly coloured, non-toxic dye is added to the water and applied with precision to targeted areas of concern. This approach makes it easier to observe how moisture travels through the building envelope and where it emerges inside. It is not about flooding the area; rather, the water and dye are directed carefully to specific junctions or interfaces.
Different coloured dyes can also be used for separate areas, allowing surveyors to distinguish between multiple defects. This is particularly valuable when providing evidence, as it enables clear identification of the exact source of each leak. As with all our testing, the chosen approach depends on the building’s characteristics and the issues under investigation. Water and dye testing is especially useful for complex junctions or areas with multiple layers of construction.
In this case, the technique pinpointed the source: a complicated junction between the original house and the extension—a scenario not uncommon in New Zealand buildings.
4. Thermal Imaging
Finally, another ‘tool from the toolbox’ we may deploy is our infrared camera. This is another non-invasive technique which can detect temperature differences in building materials, revealing cold spots that may indicate moisture intrusion or insulation gaps. However accurate interpretation does require highly controlled conditions, so while it can be a useful indicator, we don’t always rely on it.
5. Destructive Testing
If non-invasive methods are inconclusive, the only true way to identify if there are issues present, is to open up the building. This is called ‘destructive’ testing, but the process is less alarming than the name suggests! This testing involves carefully opening up parts of the building—such as removing linings, claddings, or skirtings—to inspect concealed areas for damage. When we recommend this approach, our clients are always thoroughly consulted beforehand, and permission is obtained.
As Graeme notes, “We’re often the bearer of bad news...so it’s important to approach these conversations with empathy. In the conservatory extension case, the owners were understandably anxious as parts of their ceiling were (carefully!) removed for inspection. Clear communication and reassurance were essential, and the team ensured everything was restored, once the investigation was complete.”
Documentation and Reporting
Throughout the process, our surveyors compile a detailed record of what they find; photographs, diagrams, and, where needed, laboratory reports, data analysis and modelling. This documentation provides a clear audit trail and ensures recommendations are based on verifiable facts. It also gives owners confidence that decisions are grounded in evidence, not assumptions. For further reading about the industry standards we follow, visit the RICSs site)
Diagnosing the Root Cause
Diagnosing the root cause is where insight matters most. Our surveyors will review the evidence to understand why the problem occurred. This could be because of, or a combination of, design flaws, poor workmanship or material failure. This step, and accurate diagnosis, ensures solutions address the underlying issue rather than just the symptoms, reducing the risk of repeat problems and unnecessary expense.
Remediation Recommendations
Finally, based on findings, our surveyors can then develop recommendations for remediation that address both immediate concerns and long-term building integrity. While our Building Surveyors may work alongside designers and builders, their role remains independent and advisory, ensuring solutions are fit for purpose and compliant with regulations.
No Guess Work
As you can see, investigating building issues is a structured process, grounded in evidence and experience. So, what does all this mean for property owners? After walking through the investigative process, it’s clear that prevention and informed decision-making are key. Every test and inspection we’ve discussed serves one purpose: protecting your building’s integrity, and your investment.
With that in mind, Graeme has identified some practical advice to keep in mind, whether you own a home, or manage a commercial property:
- Correct design and construction are vital for the longevity of any building work.
- Early intervention is crucial: addressing issues promptly minimises disruption and expense.
- Robust long-term maintenance planning helps maintain asset value, ensures compliance, and reduces operational risk.
- Engaging a qualified, impartial Building Surveyor is the best way to safeguard your investment and ensure peace of mind.
Need advice or support?
Our team of Building Surveyors are available to help, nationwide. Read more about our building surveying services here, and feel free to contact us with any queries.
For day-to-day insights into Building Surveying life, follow Graeme on LinkedIn.
