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Black Mould: What it is, Where it’s Found and How to Treat it

Mould is organic matter that grows according to availability of food, moisture and oxygen. Mould often appears on old food, leather and building materials that are hygroscopic. Mould doesn’t require light to grow, but will appear when organic or porous materials are left in oxygenated, moist and humid environments for too long. There are over 100,000 different subspecies of mould identified worldwide, all of which are multi cellular – with many flowers, called zygots – and these contain the spores.

Mushrooms are single-celled fungi, featuring only one spore-containing cap, Mould have multiple spore-containing zygots. The two subspecies of fungi are, however, similar in that they proliferate using a cocoon of mycelium strands.

Black mould is one particular variety of mould that is especially dangerous. Known as Stachybotrys chartarum, this mould’s spores contain a toxic defence mechanism that can be hazardous when inhaled, causing breathing and lung health issues. When black zygots have formed on the surface of a wall or ceiling, they are constantly releasing airborne spores containing toxicity, making immediate clean-up essential. This variant has been classified as more deadly than asbestos due to its method of breeding that sees it begin releasing spores into the atmosphere immediately after it has anchored itself in a cool, dark place with lots of moisture. Asbestos will not release any airborne fibres unless disturbed.

Black mould doesn’t just grow on the surface of walls, either. This variant of mould can encompass an area of 100 times larger behind the building material than what it appears on the surface. This means, unfortunately, cleaning a surface with bleach or other chemical cleaner is insufficient in most cases because the main body of the mould, Mycellium is buried deep within the material infected. Removal of the building material or contaminated area and rectifying the causation of the moisture is essential.

Homes that were built less than 40 years ago are prime targets for black mould growth due to the gradual deletion of air bricks in walls, except for sub floor ventilation. Airflow through older buildings prevented water or moisture build-up in cavities, where humidity is these days commonly trapped. Condensation will form when there is a differential of temperatures creating a Dew Point, the temperature differential level at which condensation and moisture will form. Airflow can mitigate this occurring. Black mould will find it very hard to exist if the areas are well ventilated and allowed to dry.

In a lot of new homes, some key basic requirements are forgotten in construction to maximise speed and use of cheaper materials. One testimonial reads as follows:

I lived in a terraced home in Balmain in 2003. My bed was up against an external 230mm brick wall, known as a wet wall. This home had no cavities so if the external paint had degraded, moisture was allowed to seep into the bricks.

I developed an asthma-type issue and saw my GP because I had never had breathing issues prior in my life. I was put on an inhaler.

When I got home, I checked around the room and I noticed small black spots on the wall above my headboard. I cleaned this with bleach and my health issue began to clear up. I had to clean the wall every three weeks once I noted these black spots reoccurring. The landlord obviously was not going to rectify the issue properly so that was the ongoing effort I continued to make for my health until I moved out.

If you find mould in your home, keep in mind that you get what you pay for, so call an expert, not someone jumping on the bandwagon claiming that surface cleaning will do. Contact Sydney Building Defects Inspections and Reports for a full building inspection and diagnosis – 0419 416 040 using state of the art Thermal imaging, moisture and relative humidity readings.