.png)
Box Gutter Leak, Mould and Hidden Termite Damage in Crows Nest: Why We Stopped Work
By Michael Nguyen | Indoor Environmental Professional (IEP) | IICRC WRT, AMRT, ASD (69486970) | Mould Testing Technician (NAT10913005) | Licensed Builder NSW 392154C (Supervisor, KBL+RENO)
Some jobs turn out to be bigger than they look. In this Crows Nest home we were called in for water damage and mould from a leaking box gutter. Once we removed the damaged plaster, we found termites in the wall framing. We stopped work straight away, reassessed the job and brought in the right specialists before going any further.
Here is what we found, why we stopped, and what happens next.
The Leak: A Failed Box Gutter
A box gutter is a gutter built into the roof, often between two roof sections or behind a parapet wall. When a box gutter leaks or overflows, the water goes into the building instead of off it. In this home, water from the box gutter had been getting into the walls and ceilings of the lounge room, toilet and laundry, causing water damage and mould.
Step 1: Removing the Water-Damaged Plaster
Our first step was source removal: cutting out and removing the water-damaged, mould-affected plaster so we could see the wall framing behind it and assess how far the damage went. Wet plaster that has grown mould generally can't be saved, and removing it is the only way to see what is happening inside the wall. Read more about why contaminated plasterboard sometimes needs to be removed.
What We Found: Termites in the Wall Frame
Behind the plaster we found termites and termite damage in the timber framing: mud galleries along the studs and plates, and timber that had been eaten out from the inside. Timber that has been wet for a long time is an easy target for termites, so it is not unusual to find them alongside long-term water damage.
Why We Stopped Work
Termite damage changes the job. The framing behind these walls helps hold up the second level of the house, and some of that timber was no longer sound. Carrying on with demolition and drying without knowing how strong the structure was could have put the home and our team at risk. So we stopped, made the area safe and reassessed.
Pest control: We engaged a third-party licensed pest controller to manage the termites, so they are dealt with before any timber is repaired or replaced.
Structural engineer: We engaged a structural engineer to inspect the framing and write a report on the structural integrity of the building.
Temporary propping: Next week we return to install props to support the second level, so the damaged framing can be safely worked on.
As a NSW licensed builder (392154C), we can manage the trades involved and carry out the repairs, rather than leaving the owner to coordinate everyone.
What Happens Next
Once the structure is propped and the termites are under control, we can continue with the mould remediation and drying, following the IICRC S520 standard for professional mould remediation and the IICRC S500 standard for water damage restoration. The box gutter also needs to be repaired so the leak doesn't return. We will update this post as the job progresses.
Signs of a Leaking Box Gutter
Water stains or bubbling paint on ceilings or high on walls below the roof
Mould on ceilings, cornices or upper walls after heavy rain
Musty smells in rooms under the roof line
Water dripping inside during storms
Overflowing water at the edge of the roof
If you see any of these, get it checked early. Long-term leaks don't just cause mould: they can also lead to rot and termite damage in the timber frame. A mould and moisture inspection will find where the water is going.
Mould Removal and Water Damage on the Lower North Shore
We work on homes and apartments in Crows Nest and across the Lower North Shore. For another leak that caused hidden damage, see our planter box leak and structural drying job in Lane Cove and the hidden roof leak that caused mould in a Windsor home.
Frequently Asked Questions
Can water damage attract termites?
Yes. Termites are attracted to damp timber, so long-term leaks from gutters, roofs, showers or plumbing can make a home more vulnerable. Fixing leaks quickly and drying the structure properly reduces the risk.
What is a box gutter?
A box gutter is a gutter built into the roof rather than hung on the outside edge. They are common on terraces, older homes and homes with parapet walls. Because they sit inside the roof line, a blockage or failed lining sends water into the building.
Why did you stop the mould remediation?
Because termite damage meant the strength of the wall framing was uncertain, and that framing supports the second level. Work only continues once pest control has treated the termites, a structural engineer has assessed the frame and the structure is propped.
Does home insurance cover termite damage?
Many home insurance policies exclude termite damage, while sudden water damage may be covered. Check your policy wording with your insurer. Our reports document the cause and extent of the damage to support your claim.
About the Author
Michael Nguyen is the director of AAA Mould Removal and leads our water damage and mould remediation work across Sydney. His qualifications include:
Indoor Environmental Professional (IEP) – Testing Water-Damaged Buildings, Australian College of Environmental Studies (RTO 21740), 2026. Includes nationally recognised units NAT11429003 Conduct a comprehensive mould and moisture assessment and NAT11429007 Conduct post remediation verification mould testing (11429NAT Advanced Diploma of Building Biology)
IICRC Water Damage Restoration Technician (WRT)
IICRC Applied Microbial Remediation Technician (AMRT)
IICRC Applied Structural Drying (ASD), IICRC no. 69486970
Mould Testing Technician (NAT10913005)
Licensed Builder NSW 392154C (Supervisor, Kitchen, Bathroom & Laundry and Renovation)
Carpentry Licence
Worried About a Leak, Mould or Hidden Damage?
Call AAA Mould Removal on 1300 739 783 or contact us online. We will find the moisture, remove the mould properly and dry your home to IICRC standards.
Comments