Mould infestation is not exactly a new issue but it has recently become a hot topic because of the efforts extended to increase awareness regarding the dangers of having moulds in the house or any building. If not dealt with and removed immediately, moulds can be a main culprit in triggering health problems and causing the structure to become weak. 

Since mould contamination is a complex subject, you probably have a lot of questions in mind regarding its causes, signs, effects, and most importantly the viable solutions in getting rid of mould. The good thing is, we will provide you with a one-stop guide that will leave no question unanswered about moulds and how you can get rid of them.

Everything You Need to Know About Moulds and Mould Removal

What are Moulds? 

Similar to other fungi, moulds break down dead matter in the environment, such as plants and animals. While some types are helpful (like Penicillin), others can be detrimental to health, structures of buildings and crops. Their reproduction process involves releasing spores that scatter through the air, water, or plants and animals. Places that have moisture, a warm atmosphere, and organic materials that serve as food for them (like paper, wood, carpet, soil, dust, and dirt) are prone to mould formation. In other words, they especially love to grow in your home. 

What’s the Difference Between Moulds and Mildew?

Moulds are often mistaken as mildew. Although direct association exists between the two, they are not exactly the same. Mildew is a common type of mould found in homes. In short, not all moulds are mildew but all mildew are moulds.

Mildews are typically found in the bathroom, on fabrics and books stored for a long period. Although it can damage surfaces and the overall structure of your home, they are not the most dangerous types of mould that you can encounter.

What are the Common Types of Moulds Found in Households?


One of the most common moulds that grow in homes, aspergillus has long and flask-shaped spores that develop into thick layers or walls of mould. Its colours vary across over a hundred species. It especially forms abundantly during autumn or winter.

Although most strains of aspergillus are not harmful, the spores released might trigger allergies. It can also become more dangerous depending on the environment, causing mild to serious lung infections such as asthma attacks and aspergillosis. Aspergillus can also produce a deadly carcinogen called aflatoxin.


Just like aspergillus, Cladosporium is also an allergenic type of mould that can irritate the eyes, nose, throat, and skin. But unlike most types of moulds, it possesses a unique ability to thrive in both warm and cold conditions. It is normally found indoors so you might as well have your carpet, upholsteries, and fabrics inspected. The inside cupboards and under the floorboards are also prone to Cladosporium formation. In terms of colour, it appears olive-green or brown with a texture of suede. Although non-toxic, Cladospurium is not advisable to be handled directly as it can potentially cause lung and skin irritations.  

Stachybotrys or Black Mould

Known as the evil type of mould, the Stachybotrys is a dark green or black slimy mould that produces toxins and triggers allergic reactions. It flourishes in damp and wet areas with high levels of humidity and on cellulose materials like wood, paper, cardboard, wicker, or hay.

Frequent exposure to mycotoxins that Stachybotrys release can result in serious health issues. Below are the effects of getting in contact with black moulds.

Symptoms of Black Mould Exposure

    • Chest tightening or difficulty breathing
    • Burning sensations in the airways
    • Sinusitis
    • Non-stop coughing
    • Nose bleeds
    • Fever 
    • Severe headaches
    • Fatigue 
    • Depression

If you have children at home, contact a mold remediation service provider immediately since these toxic moulds can lead to neurological problems and pulmonary bleeding in infants.


Trichoderma takes form in clusters of wool-texture moulds that are usually white in colour with greenish patches. Like other moulds, they also reproduce in environments with a high build-up of moisture and condensation such as wallpapers, damp fabrics, carpet and even in your air conditioning filters and ventilation ducts.

Most of trichoderma moulds are identified as non-pathogenic. However, there are some species that can lead to infections in the liver (hepatic) and pulmonary system.

How Do You Know When a Building is Contaminated with Mould? 

You need to be aware of the early signs of mould infestations so you can easily detect them whenever they arise. These indicators can typically be observed in the odour, building deterioration, and persistence of health problems that have no clear roots or reasons.

Common Signs of Mould Formation

    • Musty smell
    • Cracked or blistering paint and wallpapers
    • Bulging walls
    • Dark grouts in your shower tiles
    • Cracked tiles
    • Spongy floor or walls
    • Cold or runny nose that never seem to subside
    • Continuous occurrence of seasonal allergies
    • Coloured (usually dark) spots on the wall 
    • Worsening of asthma
    • Itchiness
    • Feeling tired all the time
    • New building

Did you know? Modern homes are actually prone to mould growth as compared to old, drafty stone homes since newly-built buildings today have tight structures that allows the accumulation of water and damp rather than having a natural ventilation. Also, modern appliances generate heat, causing the build-up of moisture.

Where Do Moulds Usually Grow?

As a rule of thumb, environments with high levels of humidity are prone to mould infestation.

Areas Where Moulds Are Likely to Develop

    • Roof 
    • Gutters
    • Around chimneys
    • Ducts
    • Attics
    • Rain-affected areas
    • Kitchens
    • Bathroom tiles
    • Under sinks
    • Windows
    • Refrigerators (especially seal on the door)
    • Furnitures
    • Carpets
    • Wall interiors
    • Wallpapers
    • Crawl spaces
    • Basement walls
    • Furnaces
    • Insulation systems 
    • Humidification systems
    • Near foundation air vents
    • Under window unit air conditioner

What Causes Mould Formation?

Generally, moisture is the top culprit of mould contamination. Areas that are wet or damp make an ideal environment for moulds to reproduce.

Plumbing Leaks

If left unfixed, pipes with leakage can cause growth of moulds. The worse thing is that it might be difficult to detect plumbing leaks since they are sometimes hidden inside a wall. Most of the time, mould infestation has already become extreme before they are discovered. You should always watch out for slow leaks in the pipe fixtures.

Roof Leaks

Just like in plumbing leaks, moulds growing in roof cannot easily be spotted since leakage are also usually discovered late. To prevent this, make it a habit to check the attic regularly and look out for hints of water damage in the ceiling. 


As a result of a chilly temperature, condensation normally occurs on cold surfaces such as metal pipes and concrete floors. 

Poor Room Ventilation

A poorly ventilated room is a prime spot for mould formation. Bad air quality indoor happens when there is an imbalanced system of fresh air coming in and polluted air that is being exhausted. It can pave the way for moist pockets where moulds especially love to spread. This is why it is important that you maintain a proper ventilation system to keep the moisture level balanced. The two sections in your home that need utmost attention with ventilation are your bathroom and kitchen, since this is where most steaming activities occur.

Damp Clothes

Leaving wet clothes inside the house for a long time is never a good idea, unless you’re fine with having to deal with moulds. These harmful fungi can either form on the cloth itself or around the surfaces, since the dampness can release moisture in an enclosed environment like your home. The piles of damp clothes left unwashed for more than a day can cause moulds or the clothes that are already washed but are dried indoors are ideal spots for moulds. Unless the room has proper ventilation and your dryer is vented outside the house, it is recommended to have your clothes dried by the natural heat from the sun.


If the building has been affected by flooding, moulds are most likely expected to develop since it usually takes days or even weeks for the wet areas to dry out. Note that any damp surface left undried for more than 24 hours already poses a huge risk of mould formation. If not resolved immediately, moulds can be a long-term problem following the damages caused by the disaster. 

Note: A dangerous mould Stachybotrys chartarum or black moulds usually require extreme environmental conditions for them to grow and the after-flood area is exactly what they need to infest the building. 

Wet Basement

Any room with high levels of moisture is generally mould-friendly. But the emergence of mould is most likely to occur in the basement due to a number of factors. First, it’s often more humid and lacks good ventilation as compared to other rooms. It is also where the leaking water normally ends up due to its low position. Moreover, the basement is often neglected and rarely maintained so moulds might not be discovered right away. 

Other Causes of Moulds

There are many other conditions that supply the requirements for moulds to begin infesting a building. These include:

  • Darkness (moulds cannot thrive under ultraviolet light)
  • Cooking
  • Showering
  • Humidifiers
  • Drainage Problems

What are the different levels of mould damage? 

Level 1: Less than 10 Square Feet of Mould Damage 

The first level of mould contamination refers to the damage that covers a small area, specifically 10 square feet or less. Normally, it is indicated by the formation of mould spores in ceiling tiles, baseboards and walls with presence of excessive moisture. If you happen to encounter this level of mould damage, professional help may not be needed as it is relatively easy to remove. You simply have to brush and wipe the mould surfaces then apply a detergent solution using a rag or cloth. This method can come in handy in wooden types of materials and non-porous surfaces, like metals, glass, and tiles.

But before you perform any mould clean-up technique, even if it’s as basic as Level 1, you need to be aware of these precautionary actions.

Safety Measures When Performing Level 1 Mould Removal at Home

  1. People with allergies, asthma and immune disorders are not advisable to come in close contact with moulds, neither should they do the mould remediation procedure.
  2. Children and elderly should also keep distance from the work area.
  3. Wear rubber gloves, goggles, breathing mask and a disposable respirator for personal protection.
  4. Apply proper cleaning products and ensure that they are completely dried before returning them for regular use.
  5. Make sure to thoroughly clean the used tools and materials.
  6. If you used disposable items or materials that are difficult to clean, observe proper disposal and tightly seal them in garbage bags to avoid the spreading of spores.
  7. Wait for the area to be fully dry before the residents can move back in. Be sure to maintain proper ventilation to speed up the drying process.

Level 2: 10 to 30 Square Feet of Mould Damage 

A mould damage that reaches 10-30 square feet indicate Level 2 contamination. Although not applicable to all cases, this may be a cause of plumbing and air conditioning issues. A deliberate inspection of the building is recommended if the mould spreads to the entire wallboard panel.

Similar to the first level, you can fix the Level 2 mould damage on your own. But then again, safety measures shouldn’t go neglected if you decide to do so.

Safety Measures When Performing Level 2 Mould Removal at Home

  1. Locate the source that highly produces moisture and take actions to prevent mould growth in this area.
  2. For disposal, contain the contaminated materials inside the plastic and use tape to seal the sheets.
  3. Use a vacuum cleaner with HEPA filter in drying the area.

Level 3: 30 to 100 Square Feet of Mould Damage 

If mould contamination goes stretches from 30 to 100 square feet, then you are dealing with the third level of damage. This is typically characterised by larger surfaces such as wallboards, ceiling tiles. Contrary to the previous levels, this suggests a much bigger problem that demands an immediate solution. It is also recommended to have a professional mould remediator test and inspect the area so they can decide on the most ideal course of action. But if you decide to conduct the mould remediation on your own, please note the following preventive actions.

Safety Measures When Performing Level 3 Mould Removal at Home

  1. Seal doorways and other openings with plastic sheets to isolate the affected area.
  2. Don’t let the children and elderly enter the area until the work is finished.
  3. Sanitise the outer covering of enclosed bags that contain the contaminated materials before disposing them.

Level 4: Over 100 Square Feet of Mould Damage

The fourth level of mould damage should already alarm you as it covers a much larger surface area (more than 100 square feet). This carries potential health risks and would require the help from a professional mould remediation company. Unlike the lower levels, the procedure for level 4 is not simple and will need adept knowledge and training to completely remove the moulds. They usually utilise a decontamination chamber for disposal and air filtration equipment with HEPA filters. This will allow them to keep track of the indoor air quality to determine when it is safe to resume activities.

Level 5: Mould Damage in the HVAC System

When moulds start to spread through your HVAC system, you should leave it to the care of professionals, regardless how small or large the damaged area is. Certain safety measures, along with the previously mentioned, should be observed. The HVAC system must be turned off and biocide products must be used.

What are the Symptoms and Effects of Exposure to Toxic Moulds?

Mould exposure carries varying symptoms and effects. Among the common symptoms of exposure to moulds are allergies and irritations. People with weak immune systems are at risk of experiencing infections and illnesses 

  • Coughing, Sneezing, and Difficulty Breathing
  • Eye Irritations
  • Throat Irritations
  • Headache
  • Asthmatic reactions
  • Pulmonary hemorrhage

How Can Moulds be Removed?

There are two ways to remove moulds: you can either do it on your own through the use of cleaning products or acquire services from a professional mould remediation company.

Steps in DIY Mould Clean-Up 

  1. Wear the necessary protective materials such as goggles, non-porous gloves, and a mask to cover your nose and mouth. 
  2. Keep the windows open to provide fresh air but close the doors to prevent spores from spreading to other rooms. 
  3. Remove from the curtains, toys, clothes and cushions from the contaminated area. Seal them tightly in plastic bags and clean them before returning. 
  4. Use warm water with soap and thoroughly wipe the infested surface with a rag. Don’t spray moulds with chemicals since this can only lead to dispersal of spores into the air.
  5. You can also apply bleach-containing products, such as chlorine bleach, to disinfect the area.
    Note: Refrain from mixing the bleach with other household cleaners (especially ammonia) because the chemical reactions may result in the production of toxic fumes.
  6. Afterwards, wipe the surface with a dry and clean rag. Then vacuum the room to ensure the complete removal of residual spores.

While these steps are undeniably quick and easy routines to perform on your own, you also need to consider the effectiveness and success of mould removal. For instance, even though evidence shows that bleach can indeed kill fungi, a concentration of 10% is required for it to deliver the job. Most commercially available cleaning products contain less than 5% of bleach. Moreover, bleach is known to have a short shelf life, making its potency vanish over time. These products may only contain 0.6% bleach concentration towards the end of its shelf life. 

But regardless of the potency level, the cleaning agent may only be able to remove mould on the surface but it can’t penetrate through porous materials, like the grout and plaster. Some experts even describe bleach to be a mere masking agent. Yes, it can wash away the dark colours (or melanin) of fungi. But just because they’re no longer visible to the human eye doesn’t always mean that the moulds have been completely scraped away. 

In general, professional mould remediation is still recommended, especially if you’re dealing with mould infestations that cover a much larger area.

What is the Process of Mould Remediation?

Depending on the mould abatement company that you hired, the exact process may vary. But here are the methods that most removalists follow, including AWARE, a professional mould remediation and removal company in Melbourne, Australia. 

1. Mould Contamination Assessment 

The initial stage to resolving an issue is tracing its root cause. During the assessment, expect the removalists to determine the extent of mould contamination and recommend ways to solve the mould problem. 

2. Planning and Setting the Scope of Works

In this step, mould removal companies will outline the methods of removal, cleaning, disinfection and the repair of the affected areas. This is also where you will know the estimated cost and time required to finish the job. 

3. Containing the Infested Area

Contaminated areas are sealed off to prevent the mould from spreading to other rooms during the process. 

4. Mould Removal and Remediation

During the actual abatement work, moulds and fungi are physically removed from the surface. In cases where moulds have grown deep down the surface pores and narrow gaps, sanitisation and other techniques are used instead of physical elimination. 

5. Drying 

To remove the remaining moisture and avoid fungi from growing back, the affected area should be properly dried after the removal. 

6. Structural Restoration

It is necessary to reorganise and rebuild the damaged area. Replastering and repainting are commonly done in this step. 

7. Reporting and Evaluation

Ideally, removalists should present final reports regarding the issue, method, and results of the mould abatement done. 

How Much Does Professional Mould Remediation Services Usually Cost?

The cost usually depends on the infested area and as per assessment of the mould remediation service providers. In general, the range may go as low as $500 up to $30,000. 

Should You Leave Home During the Process of Mould Remediation?

No, this is one of the common myths surrounding mould remediation. Although the procedure time-consuming and labor-intensive, it doesn’t require the residents or occupants to vacate the area, unless you insist on doing so. 

How Long Does the Procedure Take? 

Typically, mould abatement takes one to three days to finish, depending on the severity of the mould issue and the crew size of the removalist company. 

How Do You Prevent Mould from Recurring?

Getting rid of mould doesn’t end in the process of mould remediation. You should be aware of the measures that will prevent mould growth from recurring. Remember the tips listed below to save you from facing the same troubles in the future. 

1. Inspect for the Presence of Water Leakage in the Building

Checking the roof and pipes regularly will allow you to discover the source of moisture before the moulds even start to grow. Once broken plumbing is detected, fix the problem right away. 

2. Install Proper Ventilation 

Poor ventilation is one of the main culprits of mould formation. Use exhaust fans to vent out polluted air outside the building. The kitchen and bathroom will need them