Mould Testing NZ — Mould Assessments & Mould Air Testing Nationwide
We test the air and surfaces and find the moisture behind the mould, in homes, rentals and workplaces across New Zealand
Mould Inspection and Detection, Anywhere in NZ
A professional mould inspection looks further than what you can see. Our mycologists and occupational hygienists test the air and surfaces and measure moisture in the building, to find out what is growing, how serious it is and what is feeding it. Every area is rated against the ANSI/IICRC S520 (2024) standard, and you get a written report with clear next steps.
Our own team covers the Waikato, Bay of Plenty and Auckland. Elsewhere, including Wellington, Christchurch and Dunedin, a trusted assessor from our national network visits. Whoever takes the samples, they are analysed in our own Hamilton laboratory.
Book Your AssessmentWhat a Mould Assessment Costs
No two properties are the same, so the fee depends on the distance travelled and the size and complexity of the site. As a guide:
$800–$1,200 ex. GST for a typical home. That covers the visit by a senior occupational hygienist and mycologist, the sampling, the lab analysis and a full written report.
Larger or more complex investigations, such as insurance claims, tenancy disputes, possible legal action or mycotoxin exposure, are quoted individually. Tell us what you need the assessment to show and we'll plan it around your budget. Get in touch to talk it through.
Mould Air Quality Testing for Homes and Rentals
A mould air test measures how many fungal spores are in the air of a room and which genera they belong to. A calibrated pump draws a known volume of air through a spore-trap cassette; the cassette is read under the microscope in our Hamilton laboratory to ASTM D7391-20, and the result is reported as fungal structures per cubic metre of air.
The number on its own means little, because New Zealand outdoor air always carries spores, and the mix shifts with the season and the weather. So every air test is read against an outdoor reference sample taken at the same property on the same day. Indoor counts that sit close to outdoor, with the same genera, are normal background. Indoor counts that are elevated, or dominated by water-damage indicator genera that are absent outside, point to a source inside the building, often one you can't see.
Air testing is the right tool when there is a musty smell but no visible growth, when occupants have symptoms, after a leak or flood, before and after remediation, and in rental properties where a landlord and tenant need an independent measurement rather than an opinion. It is usually taken alongside surface sampling and moisture readings as part of a full assessment, but stand-alone air testing can be arranged where that is all the situation needs.
Testing the air in a workplace, such as an office, workshop or plant, for VOCs, CO2, dust or exposure standards? That is our workplace indoor air quality service.
What a Scaada Mould Assessment Includes
Unlike a single mould test, an assessment is a full on-site investigation by specialists trained as both mycologists and occupational hygienists. You find out what mould is present, how serious it is, and where the moisture feeding it is coming from.
1 · Site inspection
We walk through the whole property, recording visible mould, signs of water damage and ventilation problems, and noting where hidden growth is likely. This decides where we sample.
2 · Air & surface sampling
Spore-trap cassettes measure airborne spores and tape lifts capture growth on surfaces, with an outdoor reference sample taken the same day for comparison.
3 · Moisture mapping
Moisture, temperature and humidity readings, taken without damaging anything, track down the water feeding the mould.
4 · Laboratory report
McCrone-certified analysis to ASTM methods, returned as a signed report with IICRC S520 condition ratings and clear next steps.
How We Sample, and Why
An assessment combines three measurement methods. Together they reveal not just what mould is present, but whether it is actively growing and where the moisture feeding it is coming from.
Air sampling
A calibrated pump draws air through a spore-trap cassette at 15 litres per minute, and spores and fungal fragments in the air stick to a slide inside. Indoor results only mean something next to an outdoor sample, so every assessment includes one taken the same day. We analyse the slides to ASTM D7391-20, count the fungal particles per cubic metre of air, identify the genera present, and interpret the results using ACGIH guidance on airborne biological particles.
Surface sampling
A tape lift picks up a 4 cm² sample from the affected surface, keeping the spores and hyphae in place as they grew. Our analysis to ASTM D7658-17 identifies the genera and counts the spores per square centimetre. Most importantly, it shows whether the mould is actively growing there or is just spores that have settled from elsewhere. Worried about black mould? This is the reliable way to confirm whether dark growth is Stachybotrys chartarum or one of its many look-alikes. Taking one yourself? Follow our tape lift instruction sheet (PDF).
Moisture & environmental measurement
Mould is a symptom of moisture. We use a professional FLIR moisture meter to take readings across building materials without damaging them (timber framing should be below 15% moisture content), along with temperature and relative humidity. NZS 4303:1990 recommends keeping indoor humidity below 60%, and readings that stay above that let mould grow even where surfaces look dry. Together with the sample results, this builds a moisture map that points to the real source: a roof leak, a plumbing failure, condensation, rising damp or a weathertightness fault.
Standards & Methodology We Follow
We follow internationally recognised standards, so our results are consistent and stand up with insurers, in legal matters and with health professionals.
- ANSI/IICRC S520 (2024) — Standard for Professional Mould Remediation. Provides the condition rating framework (Condition 1, 2, 3) used to classify mould contamination and determine appropriate remediation scope
- NZS 4303:1990 — New Zealand Standard for Ventilation for Acceptable Indoor Air Quality. Sets the benchmark for indoor humidity levels and ventilation requirements
- ASTM D7658-17 — Standard Test Method for Direct Microscopy of Fungal Structures from Tape. Our method for surface (tape lift) samples
- ASTM D7391-20 — Standard Test Method for Categorization and Quantification of Airborne Fungal Structures. Our method for air samples
- ACGIH Bioaerosol Assessment — American Conference of Governmental Industrial Hygienists guidance for interpreting indoor air sampling results in the context of occupant health
Reading Your Results: the IICRC S520 Conditions
Every area we sample gets an IICRC S520 condition rating, a standard way of saying how serious the contamination is and what, if anything, needs to happen next.
Condition 1 · Normal
Mould levels typical of a healthy indoor environment, with no water damage or humidity issue. No remediation required.
Condition 2 · Settled spores
Elevated spores settled from contamination elsewhere or outdoors. Cleaning advised; investigate the source.
Condition 3 · Active growth
Confirmed colonisation on building materials. Professional remediation recommended, scoped to the genera and extent.
Your report explains in plain language which condition applies to each area, with the moulds identified, the indoor-versus-outdoor comparison, any water-damage moulds found, and specific recommendations for your property.
Ready to find out what you're actually dealing with?
Book an on-site assessment, or send us a sample from anywhere in New Zealand. Either way you get a McCrone-certified report with IICRC S520 condition ratings and clear next steps.
Mould Assessments Anywhere in New Zealand
Wherever your property is, we can arrange a qualified assessor, and every sample is analysed in our own Hamilton laboratory.
Our own team: Waikato, Bay of Plenty and Auckland
Our own assessors cover the Waikato, Bay of Plenty, Auckland and surrounding regions, with our own equipment.
Our assessor network: everywhere else
For Northland, Wellington, Manawatū-Whanganui, Hawke's Bay, Taranaki, Nelson, Marlborough, Canterbury, Otago, Southland and the West Coast, we coordinate with independent assessors we know and trust. They follow our sampling method and send the samples to our Hamilton lab, so you get the same Scaada NZ report whoever visits.
Lab only: send us the samples
Assessors, builders and remediation contractors can use us as their lab: request a kit, follow the tape lift instructions, fill in the sample form and courier the samples overnight.
Not sure which fits your situation? Get in touch and we'll match you to the right option for your region.
Why a Professional Assessment Beats a DIY Kit
DIY mould kits have real limits:
- Misidentification. Without trained microscopy, look-alike moulds with very different health risks are easily confused
- Only part of the picture. A single swab says nothing about hidden growth, what's in the air, or the moisture behind it
- Not accepted as evidence. Insurers and landlords rarely accept DIY kit results, and no professional stands behind them
A professional assessment gives you independent evidence that you, your insurer, your landlord or your GP can act on. It's worth booking one when symptoms are present, the affected area is larger than 1 m², mould keeps coming back after cleaning, you're buying or selling, or there's an insurance or legal angle.
Who Carries Out Your Assessment
Your samples are handled by specialists trained as both mycologists and occupational hygienists, so we interpret the results in terms of health, not just lab numbers.
Patrick Crawford
Principal Mycologist & Laboratory Director
McCrone Research Institute Certified Mycologist with 17 years' laboratory experience, and a technical assessor of ISO 17025 mould laboratories. Full Member, AIOH (MAIOH).
Holly Bredin-Grey
Mould Analyst & Occupational Hygienist
McCrone Research Institute-trained analyst and qualified Occupational Hygienist with a Graduate Certificate in Occupational Hygiene. Member, AIOH (MAIOH).
Mould Assessment FAQ
What does a professional mould assessment involve?
A professional mould assessment includes a visual inspection of your property, air sampling using calibrated spore trap cassettes, surface sampling via tape lifts, moisture content readings of building materials, and temperature and humidity measurement. All samples are analysed in our laboratory using ASTM methods, and you receive a detailed report with IICRC S520 condition ratings and clear recommendations.
How long does a mould assessment take?
The on-site assessment typically takes 1 to 2 hours depending on property size and the number of areas requiring sampling. Laboratory analysis is completed within 3 to 5 business days, with priority turnaround available for urgent cases. You'll receive your full report with results and recommendations as soon as analysis is complete.
What is the difference between a mould assessment and a mould test?
A mould test analyses a specific sample in the laboratory to identify and quantify mould genera. A mould assessment is a comprehensive on-site evaluation that includes multiple tests, moisture readings, environmental measurement, and professional interpretation — providing a complete picture of mould conditions in your property with actionable recommendations. Think of a test as one data point; an assessment is the full investigation.
What qualifications should a mould assessor have?
A qualified mould assessor should hold recognised mycology training (such as McCrone Research Institute certification), membership of a professional body such as the Australian Institute of Occupational Hygienists (AIOH), and working knowledge of ANSI/IICRC S520 remediation standards. Be cautious of providers without verifiable credentials — mould assessment is an unregulated field in New Zealand, and the quality of results varies significantly.
Do I need a professional assessment or can I test mould myself?
For small areas of visible mould where you simply want to identify the species, a DIY tape lift kit sent to our laboratory may be sufficient — contact us and we'll send one with instructions. However, professional assessment is recommended when health symptoms are present, the affected area is larger than 1 m², mould keeps returning, you are buying or selling a property, or the situation involves insurance or legal proceedings.
Do you do mould air quality testing?
Yes. Mould air testing is part of every assessment and can also be arranged on its own. We draw air through spore-trap cassettes with a calibrated pump, analyse them in our Hamilton laboratory to ASTM D7391-20, and report the indoor result against an outdoor reference sample taken the same day — for homes, rental properties and workplaces across New Zealand. See how mould air testing works.
Do you do mould assessments outside the central North Island?
Yes. Our own team carries out on-site assessments across the Waikato, Bay of Plenty, Auckland and surrounding regions. For properties further afield — Wellington, Christchurch, Dunedin, Northland and everywhere in between — we coordinate with a network of trusted independent mould assessors who follow our sampling protocol and send samples back to our Hamilton laboratory for analysis. The report you receive is the same regardless of which assessor attends, and laboratory-only sample submission is available from anywhere in NZ.
Book Your Mould Assessment
Tell us about your property and we'll recommend the right assessment for your situation.