Mould is one of the most common complaints in Sydney apartment buildings. It causes disputes between tenants, lot owners and owners corporations, and it often points to a bigger building problem. Understanding the cause is the first step to fixing it and working out who is responsible.
Common causes of mould in apartments
- Balcony and podium leaks into units below, usually from failed waterproofing membranes.
- Roof and gutter leaks in top-floor units.
- Facade and window leaks through cracked render, failed sealants and window frames.
- Bathroom leaks from failed shower waterproofing in the unit above or the unit itself.
- Condensation from poor ventilation, especially in bathrooms without ducted exhaust and in closed bedrooms.
Who is responsible?
In NSW strata schemes, responsibility usually follows the cause:
- Owners corporation: leaks from common property, which usually includes the building structure, external walls, roofs, balconies' waterproofing and often original bathroom waterproofing. Check your strata plan and by-laws, as some buildings differ.
- Lot owner: problems within their lot that are not common property, and damage caused by their own renovations.
- Occupant: condensation caused by how the unit is used, such as not using exhaust fans or ventilating, can be the occupant's responsibility.
Because responsibility depends on the source, an inspection that identifies where the water is coming from is essential.
How it is fixed
- Inspect and identify the moisture source.
- Repair the leak: balcony waterproofing, roof, facade or bathroom.
- Remove mould-affected linings and materials in the unit.
- Improve ventilation where condensation is part of the problem.
- Rebuild and make good.
Class 2 rules apply
Remedial work on Class 2 apartment buildings, including waterproofing and building repairs, is generally regulated under the Design and Building Practitioners Act 2020 and must be done by a registered builder. See our guide to Class 2 builders and DBP registration.
Strata mould remediation
METCON is DBP registered (BUP4254812, General Unrestricted) and repairs the leaks and defects behind mould in strata buildings. See our mould remediation service or strata remedial works.
Frequently asked questions
Is the owners corporation responsible for mould?
Often, when the mould is caused by leaks from common property such as balconies, roofs and external walls. Responsibility depends on the cause and your strata plan.
Can a tenant be responsible for mould?
Sometimes, where mould is caused by condensation from how the unit is used. Leaks and building defects are usually the owner's or owners corporation's responsibility.
Does strata mould remediation need a DBP registered builder?
Remedial building work on Class 2 buildings, such as waterproofing and structural repairs, generally must be done by a registered building practitioner.
