• I AM HOME Building Biology

Why you need to have a moisture and mould inspection done in your home and what does it involve

What causes mould in our homes?

Almost all modern buildings experience at least minor, and sometimes serious, water damage during their life span. Excess moisture in buildings becomes a critical factor for mould (fungal) proliferation. Mould does not need a lot of moisture to grow. A little condensation, in a bathroom or around a window sill, for example, can be enough. Common sites for indoor mould growth include bathroom tile and grout, subfloor walls, and areas around windows, near leaky water fountains, and around sinks.

Water (moisture) + Nutrients + Spores = Mould

Common sources of water or moisture include roof leaks, condensation due to high humidity or cold spots in a building, slow leaks in plumbing fixtures, poor drainage around the site, blocked/damaged gutters and downpipes, rising damp, sprinkler systems, and floods. There are also many causes that are not so obvious to the untrained eye, such as poor ventilation, inadequate insulation, contaminated air-conditioning system, close proximity to compost and still water, lack of natural light, clutter, lack of external exhausts in wet areas, poor building practices and inappropriate building materials.

Besides moisture, mould needs nutrients, or food, to grow (ACGIH 1999). Mould can grow on virtually any organic substance. Most buildings are full of organic materials that mould can use as food, including wallpapers, textiles, wood, MDF, paints, glues and even soil. In most cases, temperature is not an issue; some moulds grow in warm areas, while others prefer cool locations such as bread stored in a refrigerator. Once a building material is wet for more than 48 hours microbes may begin to proliferate and the risk of mould growth is elevated. Overtime, damp or wet building materials will start to deteriorate and may release a variety of toxic chemicals indoors.

The complicating factor is that mould does not need to be seen or smelt for it to be a potential problem. Whilst approximately 25% of mould spores are viable (live), non-viable (dead) mould spores may still contain mycotoxins, that when inhaled may have the potential to cause adverse health effects. Therefore, removing mould is very important. A mouldy smell suggests that mould is growing in the building and should be investigated (US EPA 2012).

Water-damaged homes typically not only have mould and their by-products, but also elevated bacterial loads, microbial chemicals, particulates, house dust mites and pests like cockroaches, rodents and termites as well as chemicals released by damp building materials, all of which in their own accord, can contribute to adverse health effects (Bijlsma 2018). Dust mites, in particular, are prolific in water-damaged buildings due to often elevated indoor humidity levels (above 50%). The Australasian Society of Clinical Immunology and Allergy (2014), reports that house dust mites can provoke childhood asthma, eczema, chronic or recurring sinusitis and middle ear infections.

What diseases do fungi and dampness cause?

Normally, our everyday exposure to airborne fungi in the outdoor air presents little or no risk to our health (Kemp 2010). However, the airborne fungi in the artificial environments of our buildings and dwellings have an altered composition, which can create an environment with the potential to greatly affect human health. It is known that some moulds produce allergens (substances that can cause allergic reactions), irritants, and, in some cases, potentially toxic substances or chemicals called mycotoxins (IOM 2000). Inhaling or touching mould or mould spores may cause a variety of reactions in sensitised individuals.

It has been established that adverse health effects arising from exposure to mould and dampness include in lung and skin problems like asthma, eye and skin irritations, eczema, cough, wheeze, hayfever, cold and flu like symptoms, bronchitis and pneumonia(Antova et al 2008; Fisk et al 2010; Mendell et al 2011; American Academy of Paediatrics 2006; Bornehag et al 2001). Increased susceptibility to respiratory and other infections, which last longer than “normal,” recur, and are often recalcitrant to treatment, as in immune-compromised occupants, are often reported by occupants in water-damaged buildings (AIHA 2008). Extreme fatigue, headache, memory problems, difficulty in concentrating or thinking clearly, and numbness and other nervous system effects have also been acknowledged as adverse health symptoms associated with living or working in damp buildings (WHO 2004; AIHA 2013).

These reactions can be immediate or delayed. Repeated or single exposure to mould, mould spores, or mould fragments may cause non-sensitive individuals to become sensitive to mould, and repeated exposure has the potential to increase sensitivity.

Traditionally, mould exposure was thought to elicit adverse health effects through an allergic response mechanism, however, it is now known that microbial products (mould, bacteria and other inflammagens such as beta-glucans, mannans, hemolysins, proeinases & VOCs) prolific in damp buildings may induce long-term inflammation in susceptible individuals (Portnoy, Williams & Barnes 2016). This makes it extremely difficult to determine what people in a water-damaged building react to. Is it the mould and their by-products, or the gram-negative bacteria and their endotoxins, or microbial chemicals, particulates, or house dust mites and pests like cockroaches, rodents and termites which will be attracted to a water-damaged property?

In healthy individuals, these microbes are identified by the immune system and cleared from the body via bile (Plato, Hardison & Brown 2015). However, it has been identified that 24% of the population do not have the immune response genes (HLA-DR) that are required to form antibodies to biotoxins (Shoemaker 2002), which means every time these individuals walk into a water-damaged building, a persistent inflammatory illness occurs which can affect almost any system of the body. This has been named Chronic Inflammatory Response Syndrome (CIRS) or Biotoxin Illness and was first described in 1997 by Dr Shoemaker as chronic, progressive, multi-system, multi-symptom illness characterised by fatigue and headache, brain fog (difficulty with recent memory and concentration, and loss of words mid-sentence), vertigo, metallic taste, aches and pain in joints, numbness, tingling and sleep disturbances (Shoemaker 1997; Shoemaker, House & Ryan 2014). The symptoms are similar to those diagnosed with Mast Cell Activation Syndrome (MCAS), Multiple Chemical Sensitivity (MCS) and Sick Building Syndrome (SBS) (Bijlsma 2018).

CIRS can be sequentially treated starting with avoiding exposure to a water-damaged building and taking of binders to remove toxins. If you suspect that you or a member of your family has been affected by Biotoxin Illness, please refer to a qualified medical practitioner trained in this field. You can find a list of CIRS aware or certified practitioners in Australia on

Why you should consider having a moisture and mould inspection:

  • You recently bought your home and would like to know if it is water-damaged and/or has mould, and if so, how you can deal with it or prevent it.

  • To identify not so obvious or hidden sources of moisture such as plumbing leaks or condensation potential.

  • To determine how "bad" the problem is so to speak and if professional remediation is required or if you can deal with it yourself.

  • You have second-hand or antique furniture (often contaminated with mould).

  • You had a mould issue in the past which was remediated and would like to make sure that it hasn't come back.

  • If you or other occupants living in the home are experiencing the above-named adverse health symptoms that cannot be explained with a diagnosis for any other illness.

Surface mould on the back of the cabinet in the hallway from combination of dust accumulating behind the cabinet lack of airflow and high humidity.

Do you suspect that your home is water-damaged or affected by mould? Then the best thing to do is to get an Indoor Environmental Professional (IEP), such as a building biologist or a suitably qualified occupational hygienist to conduct a moisture and mould inspection. The cost varies depending on the size of the home, qualifications of the professional as well as sampling requirements. As a guide, you are looking at around $350 to $650 (excluding sampling).

What does a moisture and mould inspection involve?

Regardless of which professional you get to inspect your home for moisture and mould, a basic inspection should include:

  • Pre-inspection interview/survey asking you questions about building and site history, including water damage and mould; health symptoms experienced by occupants; housekeeping procedures and maintenance of heating/cooling systems installed in the home, if any.

  • A thorough visual inspection of the exterior and interior to determine the existence and sources of moisture/dampness problems as well as extent of potential mould contamination.

  • An assessor should use a range of investigative tools, including thermal imaging camera, moisture meters, indoor air quality meter and a boroscope (used for closed cavities) to fully determine the extent of water damage and microbial contamination.

  • Temperature, relative humidity, specific humidity levels, dew point temperatures as well as surfaces temperatures should also be recorded both externally and inside the home.

  • An investigator should also be able to examine and comment on condensation potential, adequacy of ventilation and airflow, drainage issues as well as buiding design/materials that may contribute to moisture build-up and mould growth inside the home.

Moisture content readings being taken to bottom shelf of under sink laundry cupboard.

  • Moisture mapping and/or sampling (dust, surface or air) should be carried out. Whilst moisture mapping is essential and should be conducted with every moisture and mould assessment, sampling may or may not be required. It is best to discuss this with your chosen professional prior to the inspection as it may significantly increase the cost.

  • The ceiling cavity and subfloor should be inspected (if accessible and suspected to be/or have been water-damaged).

  • A formal written report detailing findings and site/home-specific recommendations should be provided to you after the assessment (usually within a couple of days). The report should clearly determine and quantify the extent of water damage and mould growth (both visible and hidden) in your home, identify the sources of moisture, assess the potential of particulate contamination from the source and provide a list of actionable steps that you need to take in order to address the issue and return your home to dry, pre water-damaged state. Any sampling results and implications of these results should be clearly explained in simple terms.

  • In addition, an IEP should be able to recommend a number of professionals that you may need to engage in order to rectify water-manage and/or mould in your home. These may include drainage consultants/hydrologists, rising damp specialists, roof plumbers, builders and certified remediation technicians.

If you think you need a moisture and mould assessment, don't hesitate to contact me. You can find more information on my Moisture and Mould Assessment page.

Turn your house into a healthy home!


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