Mould In Your Home

Loss Prevention


Mould can grow on almost any material, including wood, paper, drywall, carpet and food. The spores released by growing mould can be found virtually everywhere, both indoors and out. Some forms of mould grow faster than others and breathing in the spores of some moulds can be more dangerous to your health than others. All that mould needs to grow are dampness, a food source and oxygen.


Many building materials contain organic material that mould can feed on, and if these materials are damp or wet at the time of their installation you may start to see some evidence of mould as they dry.

You might also have mould because moisture is getting into the house somehow, perhaps due to a plumbing leak, a faulty or insufficient sump pump in your basement, a crack in the foundation or missing flashing on the roof.


Mould is not something covered by most insurance policies. This means that you will need to know what to do if you see mould in your home.

The first thing to do is determine the source of moisture and eliminate it. You may be able to do this on your own, however for severe cases, it’s best to call a professional.

  • If you think that it’s the result of a defect in your new home, contact your builder as your new home warranty should cover mould remediation (caused by a warranted defect) in addition to repairing the defect that’s causing the problem to begin with.
  • Mould could also be present due to improper or inadequate home maintenance.

Once you have eliminated the cause, you will have to deal with remediation of the existing mould. The Government of Canada provides information on dealing with mould here.


One of the keys to preventing mould is in the first place is managing the moisture levels in your home using proper ventilation, exhaust fans, air conditioning systems and dehumidifiers. Guidelines suggest keeping the relative humidity in your home between 30-45% to prevent mould growth.

When it comes to mould prevention it’s important that you regularly inspect window and door surfaces for moisture and condensation; inspect plumbing fixtures and immediately repair leaks; use all exhaust fans, especially in the bathroom and kitchen; and inspect the foundation, roof, windows, doors and exterior cladding for moisture intrusion.


Unless the cause of the moisture problem has been identified and solved, mould will reappear. To prevent future problems, measures should be put in place to control sources of moisture in your home, for example:

  • Ensure rain, irrigation water and snowmelt drain away from the house by sloping the grade away from the building.
  • Keep eavestroughs and downspouts clean of debris and ensure that the outflow runs away from the house and not into neighbouring foundations.
  • Use moisture tolerant materials in areas likely to get wet (kitchen, bathrooms, laundry areas).