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Wollstonecraft High-Rise Roof Leak: Mould & Moisture Inspection Case Study
By Michael Nguyen, Indoor Environmental Professional (IEP), IICRC WRT, AMRT, ASD | AAA Mould Removal
A roof leak in a high-rise unit rarely stays where you can see it. Water travels along slabs, ceiling joists and plasterboard before it shows up as a stain, and by then mould may already be growing behind the surface.
On 28 October 2026 we inspected a unit in a high-rise residential building in Wollstonecraft, on Sydney's Lower North Shore, after a roof leak damaged the ceiling. This case study walks through the two instruments we used to find and measure the moisture, what the readings told us, and the standards we follow when inspecting water-damaged buildings and collecting air and surface samples.
The Job: A Roof Leak Into a High-Rise Unit
The occupant reported water coming through the ceiling after a roof leak. In a strata building, a leak from the roof can affect several units below, so the first job is to work out how far the moisture has spread and whether conditions for mould growth already exist.
Our inspection covered:
A visual inspection of the ceiling, walls and joinery in the affected rooms
A thermal imaging sweep to find cooler, damp areas that can't be seen
Pin moisture readings to confirm and measure moisture in the building materials
Air temperature, relative humidity and dew point to rule condensation in or out
Time- and date-stamped photos of every reading for the report
How We Found the Moisture
We used two instruments: one to find the moisture and one to measure it.
FLIR MR277 thermal imaging moisture meter: we scanned the ceiling for cooler areas, because damp plasterboard is usually cooler than dry. Its built-in hygrometer also logged the room's temperature, humidity and dew point, so we could rule condensation in or out.
Protimeter MMS2 in pin mode: we confirmed the cool area with pin readings in % Wood Moisture Equivalent (%WME). Below 17 is dry, 17 to 19.9 is at risk, and 20 or more is wet.
A thermal camera shows temperature, not water, so every cool spot is confirmed with a pin reading. Read more about how a professional mould inspection works.
What the Readings Told Us
The ceiling plasterboard read 18.5 %WME, in the "at risk" band, while the room air was dry. That points to water from the leak, not humidity or condensation.
Ceiling plasterboard, pin mode (Protimeter MMS2): 18.5 %WME (yellow, at risk)
Ceiling surface temperature (FLIR MR277): about 23.1 °C (thermal range 22.3 to 23.7 °C)
Air temperature (FLIR MR277): 22.6 °C
Relative humidity (FLIR MR277): 43.6 %
Dew point (FLIR MR277): 9.6 °C
Mixing ratio (FLIR MR277): 7.41 g/kg
Vapour pressure (FLIR MR277): 1.19 kPa
Pinless moisture (relative scale) (FLIR MR277): 32.7
Why this matters:
Condensation ruled out. The dew point was 9.6 °C and the ceiling was about 23 °C. A surface has to drop to the dew point before condensation forms, and this ceiling was more than 13 °C above it.
The room air was normal. At 43.6 % RH the air was within a healthy indoor range. The moisture was in the building materials, not the air.
The plasterboard is at risk. At 18.5 %WME the ceiling is past dry but not yet saturated. Left alone, damp plasterboard and the paper facing on it can support mould growth, so it needs drying and monitoring until it reads dry again.
The thermal image showed a cooler band across part of the ceiling, which is where we focused the pin readings. All readings were photographed with time and date stamps for the report.
Standards We Follow
This inspection followed ANSI/IICRC S500 for water damage, ANSI/IICRC S520-2024 for mould, and ASTM D7338 for assessing fungal growth in buildings. When sampling is needed, we collect air samples (spore trap) and surface samples (tape lift or swab) to ASTM methods, and compare indoor air with an outdoor control sample.
In a strata building, fixing a roof leak at its source is usually the owners corporation's responsibility, so we recommend involving the strata manager early.
What an Inspection Includes and What It Costs
Our mould inspection and quote is free. A professional moisture and mould report, like the one we prepared for this job, starts from $500 + GST. Other services are quoted to suit the job:
Mould inspection and quote: visual inspection, likely cause of the problem and a written quote (Free)
Professional moisture and mould report: thermal imaging, moisture mapping, humidity and dew point readings, time-stamped photos, findings and a remediation scope written to IICRC S500 and S520 (From $500 + GST)
Biological sampling: air (spore trap) and surface (tape lift or swab) samples analysed by an independent laboratory (Quoted per sample)
NCAT and legal reports: expert reports for strata, tenancy, insurance and building disputes, including matters before the NSW Civil and Administrative Tribunal (Quoted)
If you own, rent or manage a unit with a roof leak, ceiling stain or musty smell anywhere in Sydney, call AAA Mould Removal on 1300 739 783 or book an inspection online.
See more of our work on the Lower North Shore, including our subfloor mould remediation in Wollstonecraft.
About the Author
Michael Nguyen is the director of AAA Mould Removal, a water and mould damage restoration company serving domestic and commercial clients across Sydney. His qualifications include:
Indoor Environmental Professional (IEP), Testing Water-Damaged Buildings, Australian College of Environmental Studies (RTO 21740), 2026, including NAT11429003 Comprehensive Mould and Moisture Assessment and NAT11429007 Post Remediation Verification Mould Testing (11429NAT Advanced Diploma of Building Biology)
IICRC Water Damage Restoration Technician (WRT), Applied Microbial Remediation Technician (AMRT) and Applied Structural Drying (ASD), IICRC #69486970
Mould Testing Technician (NAT10913005)
Licensed Builder NSW 392154C (Supervisor, KBL and Renovation)
Carpentry Licence
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