What to Do When You Have a Mould Problem

What to Do When You Have a Mould Problem

Mould is common in many homes and businesses and can grow virtually anywhere. More places are more prone than others and living and working with mould undetected in your home can cause health problems and invade your living space. It’s important to know what to look for and common mould symptoms to ensure you handle it correctly to keep your home and your health.

What Causes Mould in Your Home?

Mould is s a type of fungi that releases microscopic spores into the air. Mould spores are universally present in the air and are near impossible to remove, but mould needs certain conditions for it to be able to begin to grow in your home. Mould begins to form in humid, dark, and damp places and can take root on just about in surface when the conditions are present.
The complex causal chain of events that constitute a health hazard links sources of water through excessive moisture to biological growth and physical and chemical degradation and further to emission of hazardous biological and chemical agents (Figure 1).

Most Common Places Mould is Found

Although mould can be detected anywhere, the conditions are right. The most common spots mould grows in spaces where you can find high moisture levels, such as the attic, the laundry room, the bathroom, the kitchen, the basement, bathrooms, and crawlspaces. Mould isn’t always visible, and it can spread easily throughout the home when not detected.

Why It’s Important to Check for Mould

When you have mould in your building or in your home, your health can be affected in many ways depending on the type of mould you have in your home and how long you’ve been exposed to it. If you have pre-existing conditions like asthma or allergies, symptoms can be worse. Some of the most common symptoms of mould exposure are

  • Coughing and wheezing
  • Congestion
  • Sore throat
  • Eye irritation
  • Headaches
  • Dry and irritated skin
  • Chest congestion

Black mould is especially dangerous to both humans and animals. Black mould can produce mycotoxins that can lead to mould poisoning that can cause severe symptoms and even be fatal to people with weaker immune systems, such as the young, elderly, or immune diseases. For more information on the impacts of mould on your health and how to address it, visit Mould and Your Health.

Signs You Have a Mould Problem

Finding mould is not always a simple process, and while some can appear on surfaces, you’re your shower stalls, others can be more hidden and harder to detect. When mould begins to form on surfaces, it will continue to grow and reproduce and can appear black, green, or yellow and look fuzzy, velvety, slimy, and rough, and can be found in places exposed to moisture. You will want to look out for some common signs to determine if you may have a mould problem.

  • Frequent headaches, flu or cold-like symptoms that are ongoing, or respiratory symptoms that are ongoing
  • Damp, dusty, or earthy smells in your home
  • Spots on surfaces that appear black or green
  • Discoloured or stained walls or ceilings

Mould can be tough to spot and knowing where to start is half the battle. Mould is tied to underlying moisture issues and many times, removing surface mould is not enough. Even a small amount left behind can cause it to grow again.


The main ways of controlling condensation & mould are:

  • Ventilation
  • Heating
  • Insulation
  • Removal


  • Open windows and doors to ventilate the home and reduce the humidity level. Don’t forget the attic, basement and crawl spaces;
  • Install and use mechanical ventilation (exhaust fans) that are vented to outside air, particularly in the bathroom and in the kitchen while cooking. This can eliminate much of the moisture that builds up from everyday activities; and
  • Consider installing ventilation over appliances producing moisture, such as dryers, stoves, & kerosene heaters, or leave windows ajar while they are on.


  • Keep indoor moisture low. Relative humidity should be below 60% (ideally 30%-50%). Relative humidity can be measured with a humidity meter, a small, inexpensive instrument available at most hardware stores;
  • Maintain low constant heat when weather is cold or wet. Continuous, even heating is better than short bursts; and
  • Install heating in the bathroom such as heat globes.


  • Condensation forms more easily on cold surfaces, for example walls and ceilings. In many cases, those surfaces can be made warmer by improving insulation; and
  • Insulate hot and cold surfaces, such as water pipes.


  • Eradicate mould when it occurs. It is hard to remove when it has been there a while;
  • Do not dry brush the area. This could release spores into the air which can spread the mould further as well as cause an allergic reaction in some people; and
  • There are several treatments for mould:
  1. Tea Tree Oil is effective. A 3% solution or 2 teaspoons in a spray bottle with 2 cups of water will suffice. Shake well before each use;
  2. Kill mould from surfaces with an 80% white fermented vinegar solution (available from supermarkets). After applying the mixture, leave for at least 20 minutes and then lightly sponge with clean water;
  3. Remove the mould physically. Killing, but not removing the mould may allow it to grow back; and
  4. Don’t use bleach. Bleach has a high pH which makes it ineffective to kill mould. It simply bleaches it, so it looks like it has disappeared.
    REMEMBER: The only lasting cure for mould is to reduce the dampness!




  • Check the roof for leaks and broken tiles regularly;
  • Fix leaky plumbing as soon as possible;
  • Ensure weep holes on the outside of the building are not blocked. Weep holes allow drainage of water and the escape of vapour pressure from internal walls;
  • Over winter and spring the weep holes in window frames (aluminium frames) can get clogged. If clogged, water will stand in the lower window frame sections;
  • Check for doors or windows that may have broken seals;
  • Ensure vents and air ducts are not clogged;
  • Check for leaky toilets and that bathtub & kitchen sink seals are undamaged;
  • Swollen or crumbling walls or buckling floor boards should be removed; and
  • Check for stained ceiling or wall tiles.


  • Clean your bathroom frequently; Clothes & shoes must be dry before storing them;
  • Clean evaporation trays in air conditioners, & refrigerators frequently;
  • Cool mist or ultrasonic humidifiers should be cleaned according to the manufacturer’s instructions and refilled with fresh water daily;
  • Wipe away moisture on windows and walls to keep your home dry;
  • Carpets/rugs should be regularly aired & cleaned to prevent mould harbourage; and
  • If flooding occurs it is important to clean & dry the area immediately or preferably within 24-48 hours to prevent mould growth. Water-damaged carpets & building materials can harbour moulds & bacteria. It may be necessary to remove the carpet as the mould may be impossible to remove completely.


  • Allow plenty of ventilation in wardrobes. Leave doors open if possible.
  • If your wardrobe has been affected by mould growth, investigate the source of moisture and treat as soon as possible. Remove mould and allow to completely dry.
  • Use a semi-gloss paint on wooden surfaces. Untreated woods are more prone to moisture absorbency than semi-gloss painted surfaces and treated timbers.


  • Consider installing skylights in darker areas;
  • Minimise the number of indoor plants;
  • When filling your bath, add cold first, this reduces the steam produced; and
  • Let the sun into your home by opening curtains.

Garden Maintenace 

  • Don’t let the building foundation stay wet. Provide drainage from roof guttering and slope the ground away from the foundation of the building.
  • Ensure garden beds are not higher than the foundation of the building. This will prevent moisture from migrating into the wall.
  • Clean roof gutters regularly.
  • Downpipes should drain into soak wells to ensure drainage away from the house;
  • Prune overhanging trees near the roof.

If you suspect mould growing in your home, you will want to reach out to an expert to have your home tested and inspected to help you know what kind of mould you are dealing with and to help you find the best solutions to eliminate the problem. Contact Site Inspections today to find out how we help you.