Mould growth on windows

Battling Mould from Condensation: A Real Case from Penrith

At AAA Mould Removal, we recently tackled a challenging mould remediation job in Penrith that highlights a common but often misunderstood issue: condensation caused by high humidity. Our client was waking up each morning to find condensation dripping down their windows — and unfortunately, mould growth quickly followed.

This case serves as a textbook example of how daily condensation can become a breeding ground for mould, especially in Sydney suburbs like Penrith where seasonal humidity levels spike. Below, we’ll walk you through what causes this issue, how to clean the mould safely, and — most importantly — how to prevent it from coming back.

What Causes Condensation and Mould?

Condensation occurs when warm, moist air meets cold surfaces — like window glass. In Penrith, cold winter nights followed by warm mornings create the perfect conditions. You’ll see droplets forming on windows, frames, and sometimes even walls.

In the case we inspected, the occupants had water beading on their window panes every morning. This excess moisture had soaked into the timber window sills and plasterboard, creating a perfect micro-environment for black mould (Stachybotrys) and other common species like Aspergillus.

The root problem? Indoor humidity levels consistently above 60% and inadequate ventilation.

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How We Cleaned the Mould

Once we identified the source, we followed our multi-step professional remediation protocol:

1. Moisture Mapping

We used moisture meters and infrared cameras to trace moisture intrusion beyond visible areas — including behind the plasterboard and under window frames.

2. HEPA Air Filtration Setup

A commercial HEPA-filtered air scrubber was placed inside the room to prevent airborne spores from spreading during cleaning.

3. Surface Cleaning with Antimicrobial Solutions

We used a hospital-grade antimicrobial solution such as ActiChem Percide or Biosan II to safely clean and disinfect all affected surfaces. No bleach — ever.

4. Stain Removal (If Required)

Stubborn mould staining on window trims and painted walls was removed using a hydrogen peroxide-based oxidising agent.

5. HEPA Vacuuming

All hard and soft surfaces were vacuumed using a certified HEPA vacuum to capture loose spores.

6. Drying and Dehumidification

We ran industrial dehumidifiers to bring indoor humidity down to the ideal 40–50% range before we packed up.

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How to Prevent Mould from Coming Back

Mould won’t return if you address the conditions that caused it. Here’s how we advised the Penrith family — and how you can stop mould before it starts:

1. Reduce Indoor Humidity

Use a dehumidifier, especially in bedrooms and living areas.

Keep humidity below 60% (ideally 45–50%). A digital hygrometer can help monitor this.

Avoid drying clothes indoors unless using a vented dryer.

2. Ventilate Every Day

Open windows and doors for at least 15–30 minutes daily.

Install trickle vents or window ventilators if you live in an airtight home.

Run exhaust fans in bathrooms and kitchens for 10–15 minutes after showering or cooking.

3. Glazing and Insulation

Double-glazed windows or thermal films help reduce temperature differences that cause condensation.

Insulate cold surfaces where condensation frequently forms.

4. Wipe Condensation Immediately

Keep a microfibre towel handy in the morning.

Use a window vacuum or squeegee on glass panes and frames to remove moisture before it seeps into walls.

5. Treat Vulnerable Surfaces

Apply an anti-condensation coating to cold walls.

Use mould-resistant paints or mould inhibitors in humid rooms like bathrooms.

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Long-Term Solutions

For properties like the one in Penrith, we often recommend a full ventilation system audit. Options may include:

Heat recovery ventilation (HRV) systems

Positive input ventilation (PIV) units

Passive vents in ceilings or walls

Although these upgrades can be an upfront investment, they pay off in long-term health, comfort, and property value.

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Final Thoughts

The mould problem in this Penrith home was a wake-up call for the owners — but thankfully, they acted quickly. Left unchecked, mould not only damages building materials but also aggravates asthma, allergies, and respiratory conditions, especially in children and the elderly.

If you’re noticing condensation on your windows every morning, don’t wait until the mould shows up. Condensation today means mould tomorrow.

For a free inspection and humidity assessment, contact AAA Mould Removal. We don’t just clean — we solve the root of the problem.

Need help with mould in your home or business? Call us now or book online at www.aaamouldremoval.com.au. We’re based in Sydney and service Penrith, Blue Mountains, Parramatta, and beyond.

About the Author

Michael Nguyen is the founder and lead technician at AAA Mould Removal, one of Australia's trusted mould remediation companies. With industry certifications including IICRC Water Damage Restoration, Applied Microbial Remediation, and Applied Structural Drying, Michael brings expert knowledge and proven techniques to every job.

He is also a licensed builder and carpenter, holding a Diploma in Building & Construction, which gives him a deep understanding of how moisture and structural conditions contribute to mould growth in homes and buildings. Michael specialises in residential and commercial mould removal, black mould treatment, water damage restoration, and structural drying.

Currently studying a double Bachelor’s degree in Medical Science and Environmental Science at Macquarie University, Michael combines scientific expertise with hands-on experience to deliver safe, thorough, and lasting mould removal solutions. His mission is to help homeowners and property managers maintain healthy indoor environments with professional mould remediation services across Sydney and surrounding regions.

Learn more at www.aaamouldremoval.com.au or call today for a free mould inspection and quote.