Black Mould on Carpet: How to Identify It and What to Do Next

Black mould on carpet is one of the more serious water damage consequences an Australian homeowner can face. Unlike surface mildew that can be cleaned with household products, black mould requires professional remediation. Our flood damage carpet restoration service includes full mould assessment and safe removal by certified technicians who follow strict containment protocols.

What Is Black Mould?

The term black mould typically refers to Stachybotrys chartarum, a species of mould that grows on materials with high cellulose content, such as carpet backing, underlay, and timber subfloors, when they remain wet for extended periods. It is dark green or black in appearance and has a slimy texture when actively growing. It produces mycotoxins, which are toxic substances that can cause significant health problems with prolonged exposure.

It is worth noting that not all black-coloured mould is Stachybotrys. Other common mould species also appear dark, including Aspergillus and Cladosporium. Only laboratory testing can definitively identify the species. However, any dark mould growth on carpet should be treated as a serious concern and addressed by a professional regardless of the specific type.

How to Identify Black Mould on Carpet

Appearance

Black mould typically appears as dark green or black patches with a wet, slimy appearance when active. On carpet, it is often first visible at the edges and corners where moisture is highest and airflow is lowest. As it spreads, patches grow and merge. The carpet surface may appear discoloured, and the fibres may look matted or degraded in affected areas.

Smell

Black mould has a strong, distinctive musty odour that is often described as earthy or soil-like. This smell is produced by the mVOCs the mould releases as it grows and reproduces. If you notice an intense musty smell in a room, particularly at floor level, and you can see any dark discolouration on the carpet, black mould is likely present.

Texture

Lifting the edge of the carpet slightly, you may see black or green growth on the underside of the carpet or on the surface of the underlay. Stachybotrys tends to be slimy rather than powdery. If the growth has dried out, it may appear darker and more powdery, indicating an older colony.

Health Risks of Black Mould

The mycotoxins produced by black mould can cause a range of serious health effects:

• Chronic coughing and respiratory irritation
• Persistent headaches and fatigue
• Skin and eye irritation
• Difficulty concentrating and memory problems
• Immune suppression with prolonged exposure
• Severe respiratory illness in vulnerable individuals

Children, elderly people, and anyone with a compromised immune system are at the highest risk. Symptoms can be severe and may not resolve until the mould source is completely eliminated.

Why DIY Black Mould Removal Does Not Work

Many homeowners attempt to remove black mould from carpet using bleach, vinegar, or commercial mould sprays. These approaches are ineffective and potentially dangerous for several reasons. Surface treatment does not reach the mould growing in the underlay and subfloor. Disturbing mould without containment releases a massive quantity of spores into the air and spreads contamination to other rooms. Bleach does not kill mould on porous materials. It removes the surface colour but leaves the root structure (hyphae) intact, and the mould regrows within days.

The Correct Approach to Black Mould on Carpet

Professional black mould remediation involves containment of the affected area using plastic sheeting and negative air pressure to prevent spore spread, removal of the carpet and underlay with proper disposal protocols, treatment and drying of the subfloor, and clearance testing to confirm the area is safe before new flooring is installed. In most cases where black mould has been confirmed, carpet cannot be saved and must be replaced.