Professional Mould Assessments
Qualified mycologists and occupational hygienists assessing your property to international standards
Comprehensive Mould Assessment by Qualified Specialists
A professional mould assessment goes beyond visual inspection. Our McCrone-certified mycologists and MAIOH-accredited occupational hygienists use a systematic, evidence-based approach combining air sampling, surface sampling, moisture measurement, and environmental monitoring to evaluate mould conditions in your property. Results are classified to ANSI/IICRC S520 (2025) standards and reported with clear, actionable recommendations.
Book Your AssessmentWhat Does a Professional Mould Assessment Involve?
A mould assessment is a structured, on-site evaluation of your property carried out by qualified specialists — not just a sample collection. Our assessors are both trained mycologists and occupational hygienists, meaning they understand both the science of mould and the health implications of exposure.
The Assessment Process
- Visual inspection and site documentation — We walk through the property identifying visible mould, water damage indicators, ventilation issues, and areas requiring sampling
- Sampling strategy — Based on the inspection, we determine the most appropriate combination of air samples, surface samples, and moisture readings for your situation
- On-site measurement — Air sampling, surface sampling, moisture content readings, and temperature and humidity measurement are conducted throughout the property
- Laboratory analysis — All samples are analysed in our laboratory using internationally recognised ASTM test methods by our McCrone-trained analysts
- Detailed reporting — You receive a comprehensive report with species identification, contamination levels classified to IICRC S520 condition ratings, and clear recommendations for next steps
Unlike a simple mould test, an assessment provides the complete picture: what mould is present, how severe it is, where the moisture source is, and what action is needed.
Air Sampling Methodology
Airborne mould spores are invisible to the naked eye, and elevated indoor concentrations can indicate hidden mould growth or inadequate ventilation. Air sampling provides objective measurement of your indoor air quality.
How We Sample
We use a calibrated high-flow air sampling pump drawing air through spore trap capture cassettes at 15 litres per minute for 5 minutes, collecting a 75-litre total air volume per sample. Spores and fungal fragments are captured by inertial impaction onto a prepared slide within the cassette.
Indoor vs Outdoor Comparison
Every assessment includes an outdoor reference sample. This is critical — indoor results are only meaningful when compared against the outdoor baseline. Elevated indoor concentrations or a different species profile compared to outdoor air indicates an indoor mould source requiring investigation.
Laboratory Analysis
Air samples are examined under microscopy following ASTM D7391-20 methodology. We quantify fungal structures per cubic metre of air and identify mould genera present, applying ACGIH bioaerosol assessment principles to interpret the results in the context of your property.
Surface Sampling & Building Material Analysis
Surface sampling captures what is growing directly on building materials — providing species identification, contamination levels, and evidence of active colonisation versus settled spores from elsewhere.
Tape Lift Method
We use the tape lift technique to collect a 4 cm² sample from affected surfaces. This non-destructive method preserves mould spores and hyphae (filaments) in their natural arrangement, allowing reliable identification and semi-quantitative assessment under microscopy.
What We Identify
Laboratory analysis following ASTM D7658-17 methodology identifies the mould genera present, quantifies spore density per square centimetre, and determines whether the mould is actively growing (with hyphae and propagules) or consists of settled spores from an airborne source. This distinction is critical for determining the correct remediation approach.
Concerned about black mould? Surface sampling is the definitive way to confirm whether dark-coloured growth is Stachybotrys chartarum or one of many common species that appear similar to the naked eye.
Moisture & Environmental Measurement
Mould is a symptom of moisture. Without understanding the moisture conditions in your property, any remediation is addressing the effect rather than the cause. Our environmental measurements identify both existing moisture problems and conditions conducive to future growth.
Moisture Content Readings
Using a professional-grade FLIR MR60 Moisture Meter Pro, we take non-invasive moisture readings of building materials throughout the property. Readings are compared against accepted dry standards for each material type — for example, timber framing should read below 15% moisture content, while plasterboard should be approximately 1%.
Temperature & Relative Humidity
Temperature and relative humidity (RH%) readings are recorded in each sampled area. New Zealand Standard NZS 4303:1990 recommends buildings maintain average relative humidity below 60%. Readings consistently above this threshold indicate conditions that support mould germination and growth — even on surfaces that may appear dry.
Moisture Mapping
By combining moisture readings with visual inspection and sampling results, we build a moisture map of your property identifying potential sources: roof leaks, plumbing failures, condensation from poor ventilation, rising damp, or weather-tightness issues. This guides both remediation and preventive action.
Standards & Methodology We Follow
Our assessments are conducted to internationally recognised standards, ensuring results are consistent, reproducible, and defensible for insurance, legal, and health purposes.
- ANSI/IICRC S520 (2025) — 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 Examination of Fungal Structures on Building Materials. Our methodology for surface (tape lift) sample analysis
- ASTM D7391-20 — Standard Test Method for Categorisation and Quantification of Airborne Fungal Structures. Our methodology for air sample analysis
- ACGIH Bioaerosol Assessment — American Conference of Governmental Industrial Hygienists guidance for interpreting indoor air sampling results in the context of occupant health
These standards ensure our findings stand up to scrutiny — whether you need results for peace of mind, a remediation contractor, your insurer, or a legal proceeding.
Understanding Your Assessment Results
Your assessment report classifies conditions in each sampled area according to the IICRC S520 condition rating system. This provides a clear, standardised framework for understanding the severity of mould contamination in your property.
IICRC Condition Ratings
- Condition 1 — Normal Fungal Ecology: Mould levels are typical of a healthy indoor environment with no water damage or humidity issues. No remediation is required
- Condition 2 — Settled Spores: Elevated spore levels are present on surfaces, originating from contamination elsewhere in the building or from outdoor sources. Surfaces may need professional cleaning, and the source should be investigated
- Condition 3 — Active Growth: Confirmed mould colonisation with visible or hidden growth on building materials. Professional remediation by a qualified contractor is recommended, with the scope determined by species and extent
How We Interpret Results
Air and surface sampling results are compared against normal building ranges and established datasets for mould activity in indoor environments. We consider the species identified, the concentration relative to outdoor conditions, the presence of water-damage indicator species, and the environmental conditions recorded during the assessment. Your report explains what the results mean in plain language, with specific recommendations for your property.
Why Professional Assessment Matters
While DIY mould test kits are available, they have significant limitations that can lead to incorrect conclusions and wasted money. A professional assessment provides the context, expertise, and documentation that DIY testing cannot.
Risks of DIY Testing
- Incorrect identification — Without trained microscopy, species are frequently misidentified. Many common moulds look identical to the naked eye but carry very different health risks
- Incomplete picture — A single tape lift from a visible patch tells you nothing about hidden mould behind walls, airborne contamination levels, or the moisture conditions driving growth
- No professional documentation — DIY results are not accepted by insurers, cannot support legal proceedings, and carry no professional accountability
When Professional Assessment is Essential
- Health symptoms are present (respiratory issues, allergies, persistent illness)
- The affected area is larger than 1 m²
- Mould keeps returning after cleaning
- You are buying, selling, or renting a property
- The situation involves an insurance claim or legal matter
- You suspect hidden mould (musty odour without visible growth)
A professional assessment provides objective, defensible evidence of mould conditions — giving you, your insurer, your landlord, or your health professional the information needed to act with confidence.
Book Your AssessmentMould 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.
Book Your Mould Assessment
Tell us about your property and we'll recommend the right assessment for your situation.