Spotlight on Mould

Mould is part of the environment, and while it is naturally occurring in many places, we don’t want it growing on our walls in our homes.

We sat down with Tarion’s resident mould expert, Michael Chymycz, and asked him what home owners can do to help prevent mould growth in their homes. With Michael’s input here are some general thoughts on mould and some key things homeowners can do when faced with this problem.

What causes mould?

There is no such thing as a mould free building or environment. Mould – which is a type of fungus – is all around us, indoors and outdoors. Some moulds are actually good, as they play an important function in our overall ecosystem.

Moulds can be found almost anywhere; they can grow on virtually any substance when moisture is present. Outdoors, many moulds live in the soil and play a key role in the breakdown of leaves, wood, and other plant debris. Without moulds we would all be struggling with large amounts of dead plant matter. Moulds break down plant materials by digesting them, using the plant material for food.

Mould spores waft through the indoor and outdoor air continuously. When mould spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. There are moulds that can grow on wood, paper, drywall, carpet, foods, even dynamite. When excessive moisture or water accumulates indoors, mould growth will often occur, particularly if the moisture problem remains undiscovered or unaddressed. There is no practical way to eliminate all mould and mould spores in the indoor environment. The way to control indoor mould growth is to control moisture.

How do you prevent mould?

There is no way to control the presence of spores, or mould nutrients. The only way to manage mould growth is to manage the amount of moisture present.

Sources of Moisture:

1. Direct water penetration: For example, leaks in the basement, roof, around doors and windows, ice damming in winter, penetrations in the building envelope, and wet building materials.

2. Flooding: For example plumbing leaks, accidental spillage, storm flooding, and sewer backup.

3. Condensation and humidity: For example, drying of the structure, construction heaters, lifestyle, lack of insulation, lack of ventilation, and design issues.

How to address mould in your home

If you see or suspect mould growth within the home do not ignore it as it can spread quickly.

The first thing to do is to address the source of moisture. Because mould growth requires moisture to grow, it is important to eliminate the moisture source.

Homeowners may be able to remove certain amounts of mould themselves. If the area does not exceed one square meter, a home based solution may suffice. Most published guidelines recommend using an unscented soap/detergent solution to clean mould. Dry all areas after cleaning. Porous or damaged materials may require removal and disposal. The use of gloves, respirator and eye protection is advised if cleaning mould.

Keep in mind that the use of bleach for the purposes of mould removal is not recommended. Bleach is classified as an irritant and a toxin and has not been proven to kill and/or eliminate mould effectively.

If the source of mould has been addressed and the area has been cleaned, keep an eye out for future mould growth. If it recurs, it may be time to contact your builder.

Warranty coverage

The new home warranty covers the remediation of mould IF the cause of mould is from a warrantable defect in the home. Remediation for mould is covered up to $15,000. This is in addition to repairing the warranted defect that is causing the mould growth.

However, mould growth caused by improper maintenance on the part of the homeowner is not covered.

Regular home maintenance is essential

There are some simple home maintenance tasks that home owners can follow to help prevent mould growth in their homes.

Use the home’s principle exhaust as well as bathroom and kitchen range hood fans regularly to control relative humidity and moisture within the residence.

Inspect plumbing fixtures regularly and have leaks repaired promptly.

Inspect window and door surfaces for the presence of moisture/condensation. The accumulation of moisture on window and door surfaces may indicate that a dehumidifier is required and/or that air movement and ventilation should be improved within the residence.

Have the foundation, roof, windows/doors and exterior cladding inspected on a regular basis for signs of water penetration through the building envelope.


What is one of the most important things people should know about mould?

The most important thing to remember is that if you prevent moisture from entering the home you will help prevent mould growth.