Unchecked mould can lead to expensive restoration, maintenance costs and put the structure of your house in jeopardy.

When present outdoors, mould is a natural occurrence that is, for the most part completely harmless. In fact, at times mould is an important piece of an ecosystem. However, when present inside your home, mould can not only pose a risk to you and your family but also to the structure of your house. Let’s talk about what mould is, the possible effects of mould on your health and home, and how to remove it (or what you can do about it).

What is mould? What conditions does it need to grow? How common is it?

Mould is an organism belonging to the fungi family therefore it needs three main environmental conditions to grow:

• poor ventilation

• darkness

• and dampness

Like other types of fungi, mould reproduces by releasing tiny spores into the air, which can latch onto most surfaces. Poorly ventilated areas will minimise how far the spores travel, concentrating them to a small area and causing the mould to spread quickly. Mould also requires moisture, so it will typically thrive in damp areas, especially materials with a high content of cellulose (M. D’Orazio, 2012). The last condition required for mould growth is darkness. UV light attacks mould on the cellular level, damaging the nucleic acids and eventually killing the spore.

There are many possible reasons why mould may grow indoors:

• Some occupant behaviours can cause poor air circulation, such as keeping windows shut at all times, not using exhaust fans while cooking, etc.

• Climatic or season variables such as heavy rainfall, floods, temperature and high humidity.

• Inadequate maintenance or faulty plumbing and construction.

Due to the higher moisture content in the air, the most common areas for mould to grow are near bathtubs, showers, sinks and windows as well as in basement levels, subfloors and wall cavities.

The presence of mould within houses is surprisingly common. Here are some quick findings from experts on the topic:

• It is estimated that 10-50% of residential houses in Australia suffer from indoor dampness (World Health Organisation, 2009).

• One-third of new buildings in Australia are estimated to be affected by condensation issues, and very widespread across Australia (Dr Tim Law (PhD), Architectural Scientist, 2019).

• ‘The problem is particularly prevalent in recently built apartment blocks, a number of which have become unliveable owing to the presence of mould caused by poor building materials and bad workmanship, lack of ventilation and lifestyle habits’ (Archicentre Australia, 2016).

The potential impacts and effects on your health mould can cause

Mould spores travel through the air, seeking areas with ideal conditions to grow. Everyone inhales mould to some degree throughout their day. If inhaled, mould causes a variety of symptoms, ranging from mild reactions to serious health issues. In particular, mould can be detrimental to children, the elderly or those with related allergies. Touching and inhaling small amounts of mould may cause allergy-like symptoms such as:

• watery or itchy eyes

• nasal congestion

• sore throat

• headaches

Whereas significant long-term exposure can cause serious issues such as:

• acute allergic reactions

• skin infections

• lung infections

• death

How to prevent mould growth

If mould is left neglected, it may become embedded in building structures which will require specialists to restore or repair. The best way to control mould growth in your home is to prevent areas from becoming dark, damp and poorly ventilated. These conditions can be mitigated by:

• ensuring that your plumbing systems and roofs are free of leaks

• keeping your house well ventilated

• ensuring exhaust fans are used when cooking or using the bathroom

• using dehumidifiers and air conditioners to keep the relative humidity levels in your home low

How to get rid of mould

A safe way of getting rid of mould, according to Kate Browne (13 July 2020) is by using diluted vinegar. This process causes mould to overheat and die. Browne’s guide is as follows:

• Pour a concentration of 80% vinegar to 20% water into three buckets.

• Using a microfibre cloth, dip it into the first bucket, then use it for cleaning the patch of mould.

• With the same microfibre cloth, rinse it in the second bucket, then rinse again in the third to ensure cross-contamination doesn't occur.

• After using vinegar there may still be streaks or discolouration on surfaces which you should be able to remove with bleach.

• Microfibre cloths are affordable and can be washed on a hot cycle in the washing machine with vinegar up to 100 times.

Bleach can be another effective way to get rid of mould, however, keep in mind that this may erode surfaces such as tiles and grout, making them more porous and susceptible to further mould growth. To use bleach in a safe manner, use the following steps below:

1. Address the conditions that allowed the growth of mould (see the list above).

2. Provide adequate ventilation before you start cleaning; i.e. open windows.

3. Scrub the mould off the surface using cleaning agents such as diluted bleach solution (250 ml bleach to 4 L of water). Ensure to wipe the area up to 50 cm away from the edge of the mould as well to make sure you remove spores that have recently landed. Some mould may not be visible to the eye.

4. Completely dry the surface once cleaned.

Both methods of cleaning may need to be performed routinely to prevent regrowth. If you find the mould is deeply embedded in an object it will likely require full or partial replacement.

How we can help

If mould embedded in timber framing may cause it to rot and weaken and will need to be replaced. Arbiter Group can provide a range of services that can help with significant mould issues, for example:

• Provide structural assessments of affected timber framing and determine whether they need to be replaced.

• Attend a property you are considering purchasing, to determine if any areas of mould are structurally affecting the house.

• Determine the source of the mould and provide recommendations to prevent it in the future.

If you are unsure if an engineering inspection is needed, or if you have any questions relating to the information presented on this page, feel free to give us a ring and have a chat on 1300 272 483, or email us via the contact page.

J.T., Arbiter Group

References

• Archicentre Australia. (22 December, 2016). Combatting Mould in Apartments. Retrieved from https://www.archicentreaustralia.com.au/combatting-mould-in-apartments

• Browne, K. (13 July 2020). How to get rid of mould, Choice. Retrieved from https://www.choice.com.au/home-and-living/laundry-and-cleaning/surface-cleaners/articles/getting-rid-of-mould

• D’Orazio, M. (2012). Materials prone to mould growth. Toxicity of Building Materials, 334-350. https://doi.org/10.1533/9780857096357.334

• Law T. (2019). Submission for the Parliamentary Inquiry into Biotoxin-related Illnesses in Australia. Archsciences. https://www.aph.gov.au/DocumentStore.ashx?id=b0a17c9d-e92b-4bc0-b7ad-068768b32fb2&subId=658206

• World Health Organization Europe. (2009). WHO guidelines for indoor air quality: dampness and mould. World Health Organization, Geneva. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK143941/