East coast lows are among the most intense weather events that affect Illawarra homes, and they produce some of the largest mould remediation jobs in the region. In the 24 to 72 hours after a significant east coast low mould event, the decisions homeowners make directly determine whether the outcome is a managed dry-out or a full structural remediation several months later. The Bureau of Meteorology, NSW weather warnings is the real-time source to follow during events; the NSW SES, flood safety is the authority on evacuation and structural safety. This guide covers what to do once the storm has passed and it is safe to return and assess.
BLUF answer
After an east coast low, the 48-hour window is when the outcome is decided. Wet materials left undried past 48 hours are likely to develop active mould. Start with safety, then document everything for insurance, then dry aggressively. Some materials (carpet underlay, saturated insulation, wet plasterboard) need to come out rather than being dried in place. Professional water damage services are essential for anything beyond minor surface water.
Why east coast lows produce so much mould
East coast lows are low-pressure weather systems that develop in the Tasman Sea and track southward along the NSW coast. They combine high rainfall intensity with extended duration (sometimes two to four days of continuous rain), strong southerly and south-easterly winds that drive water into building faces not designed for sustained wind-driven rain, and storm surge that can affect coastal and low-lying properties.
The Illawarra is particularly exposed because the coastal strip has no sheltering landmass to the east or south-east, and the escarpment forces weather systems to dump additional rainfall on the coastal plain. Suburbs including Wollongong, Thirroul, Corrimal, Warrawong and Shellharbour all experience elevated storm rainfall relative to equivalent inland distances from the coast.
The result is that east coast lows introduce water into buildings through routes that normal rainfall would not reach: under lifted roof tiles, through window frame perimeter seals that are adequate for normal rain but not sustained wind-driven water, into subfloor voids through overwhelmed drainage, and as surface flooding in low-lying areas.
Our salt air and coastal humidity guide has relevant background on why Illawarra homes are particularly mould-susceptible in the aftermath of water entry events.
First 48 hours: drying priorities
Safety first. Do not enter a flooded building until power is confirmed off at the switchboard or the building is confirmed safe by SES or an electrician. Floodwater may contain sewage, chemicals and debris. Wear waterproof boots and gloves when working in any wet area post-flood.
Document before you remove anything. Photograph and video the extent of damage: floor levels of water ingress, all affected rooms, damaged contents, exterior damage. This documentation is the foundation of any insurance claim. Our mould insurance claim tips guide covers exactly what insurers need to see.
Remove standing water first. Wet vacuums, pump and bucket: the priority is removing pooled water from the floor. Every litre of water that stays on the floor extends the drying timeline for the floor structure below it.
Open windows and doors when weather permits. Cross-ventilation is one of the cheapest and most effective drying tools. If the storm has passed and outside air is dry and warm, open everything.
Set up fans and dehumidifiers. Air movement accelerates evaporation from wet surfaces. Fans directed across wet floors and walls, combined with a dehumidifier to remove the moisture they evaporate into the air, are the standard dry-out combination for residential water events.
Contact your insurer within 24 hours. Most policies require prompt notification of a claim. Early notification also means the insurer can authorise a professional water damage contractor if the extent warrants it.
What to remove vs what can be saved
This triage decision is one of the most important and most often wrong decisions homeowners make after a water event. The instinct to save everything frequently results in retaining materials that stay wet and feed mould under the surface.
| Material | General assessment |
|---|---|
| Carpet underlay | Remove. Foam and felt underlay holds water and rarely dries effectively. The mould risk from wet underlay in situ is high within 48 hours. |
| Solid timber flooring | Often savable if dried within 48 hours and the underside can also dry. Cupping is likely; the floor may need re-sanding later. |
| Carpet | Depends on the fibre type and extent of contamination. Clean water in brief contact: potentially cleanable. Sewage-contaminated or long-wet: remove. |
| Paper-faced plasterboard | Remove if saturated. Wet plasterboard is structurally compromised and provides an ideal mould substrate. Strip to framing level. |
| Insulation batts | Remove if saturated. Wet batts cannot be dried effectively in situ and sustain mould growth for months. |
| Solid timber framing | Retain and dry. Structural timber, once dried and treated, is generally sound. Monitor for mould on the surface during drying. |
| Upholstered furniture | Depends on extent and contamination. Sewage-contaminated: discard. Rainwater-only, brief contact: may be cleanable. See our mould on mattresses and soft furnishings guide. |
| Books and paper | Discard if saturated. Mould establishes rapidly on wet paper. |
| Electrical appliances | Do not reconnect without an electrician’s assessment. |
When a professional dry-out is essential
A professional water damage and mould service is not a luxury after a significant east coast low event. It is often the difference between a four-week recovery and a four-month one. Call a professional when:
- Water has entered a wall cavity or subfloor void and normal airflow cannot reach it
- More than one room is affected
- Water entry has been sustained over more than a few hours
- You are not confident the structure can be dried within 48 hours with what you have available
- The insurer has agreed to fund professional dry-out
Commercial drying equipment, including high-volume air movers and refrigerant dehumidifiers, shifts significantly more moisture than domestic fans. In a sealed wall cavity or subfloor void, it is essentially the only tool that works.
Insurance and documentation
Most home insurance policies cover sudden storm and water damage from east coast lows. The following affect claim outcomes:
- Pre-existing maintenance issues (broken tiles, known leaks, blocked gutters) may result in the insurer attributing part of the damage to neglect rather than the storm
- Delay in notification can complicate claims
- Discarding damaged items before assessment can reduce the claim value
Our mould and home insurance guide covers what typical policies cover and how to present the claim. Our mould after storms guide has more context on the local weather patterns.
For roofing specifically, our roof leak mould first 72 hours guide covers the sequence for roof-entry water. For gutter and drainage contributions to the event, our gutter drainage mould guide is relevant.
If a professional mould remediation service is needed after the dry-out, we can assess and scope the job once materials are dry.
Contact us to discuss your post-event situation and we will give you an honest assessment of what stage you are at and what is needed next.
FAQs
How long do I have before mould starts after an east coast low?
In warm Illawarra conditions, mould can establish on wet timber, plasterboard and soft furnishings within 48 hours. In cooler winter conditions, the window extends slightly but not dramatically. The 48-hour target for beginning active drying is the right frame regardless of season.
Can I claim mould remediation on insurance after an east coast low?
Mould that develops as a direct consequence of a covered storm event may be claimable as part of the storm damage claim. The key is demonstrating that the mould was caused by the event, not by pre-existing neglect or gradual damp. Documentation of the storm entry, immediate drying action, and prompt insurer notification all support this. See our mould insurance claim tips guide for the detail.
My neighbours have stripped their walls already. Should I?
Only strip materials once you have documented the damage thoroughly and, if insured, notified your insurer and confirmed they do not need to assess first. Most insurers allow urgent mitigation work (removing standing water, opening walls to dry cavities) before a formal assessment, but check with your insurer before removing significant material. Keep any removed material for assessment if possible.
What if I can smell mould already, two days after the event?
Active mould smell two days after a water event means mould has established and is growing. The drying approach needs to be professional and fast. In Illawarra coastal conditions, once mould is actively growing in a wall cavity or under floor coverings, spot-cleaning will not resolve it. A proper assessment of the extent and scope of remediation is needed.
Is it safe to sleep in the house after an east coast low?
If the house is structurally sound, power is safely restored, and water has been removed, sleeping in the home is generally safe. However, if there is active mould smell, wet materials that have not been dried, or contaminated water has been in contact with living areas, sleeping elsewhere while drying and cleaning proceeds is the more conservative choice, particularly for children, elderly residents or those with respiratory conditions.
Related reading
- Mould after storms in the Illawarra
- Roof leak mould: the first 72 hours
- Gutter and drainage mould guide
- Mould and home insurance
- Mould insurance claim tips NSW
- Mould on mattresses, carpets and soft furnishings
- Salt air and coastal humidity mould
- Water damage and mould service
- Mould remediation service