Understanding Molds in the Home

Most people spend a great deal of time in their homes, which is why it’s so important to ensure that homes remain healthy environments; free of mold.

Some Quick Facts about Mold:

– Can be harmful or helpful – depending where it grows

– Needs moisture to grow

– Does not grow on dry materials

– Mold growing inside a home can affect the occupants

– Occupants can learn to recognize mold

Molds are microscopic fungi, a group of organisms which also includes mushrooms and yeasts.  Fungi are highly adaptable to grow and reproduce rapidly, producing spores and mycelia in the process.  If fungi start to grow indoors to the point they fruit and give off spores, it will affect human health, as there is a consensus that fungi should not be allowed to grow in buildings.

What Makes Molds Grow?

– Condensation on surfaces due to excessive humidity, lack of ventilation, or low temperature (CLICK HERE for more information on Condensation)

– Steam or excess moisture in the air from baths/showers and cooking

– Water leakage, such as from a roof or plumbing leak, a cracked basement, or flooding

Molds will grow if we provide them with moisture and nutrients.  If we keep things dry, molds do not grow.  Moisture accumulates within the home when there is not enough ventilation to expel that moisture.

Common Materials Where Molds Can Be Found:

– Drywall

– Wood, such as window sills, wall framing and firewood

– Paper products such as cardboard boxes

– Damp materials such as carpeting or furniture

Areas in Your Home to Check for Mold:

– The basement

– Under or behind stored items

– Under the kitchen or bathroom sink

– On the wall or floor next to the bathtub or shower

– At the bottom edge of windows

– Closets

– Other damp places in your home

Not all mold is obvious.  It can grow inside walls or above ceiling tiles.  Check for mold in damp places or where water damage has happened.

Estimating the Area of Mold

Mold is considered to cover a small area if the patch is no larger than a square meter.  There should be no more than three patches, each patch smaller than a square meter.

How to clean up small mold problems:

– ‘Small areas’ of mold can be cleaned with a detergent solution

– Wear a mask, safety goggles and rubber gloves

– Seek professional help if there is a lot of mold or if mold comes back after cleaning

The mold area is considered to be moderate if there are more than three patches, each patch smaller than a square meter; or there is one or more isolated patches larger than a square meter but smaller than 3 square meters.  Assessment by a professional is recommended.

How to clean up moderate mold problems:

– Clean ‘moderate areas’ of mold, but wear proper protective equipment and follow precautions

– Seek professional help if there is a lot of mold or if mold comes back after cleaning

A mold area is considered extensive if a single patch of mold is larger in area than a sheet of plywood.  Being exposed to this much mold is not a good idea.  Do not attempt to clean up large areas yourself.

Do not attempt to clean up large areas of mold on your own.  You need professional help to determine why the mold is there in the first place and how to clean it up.

How to Take Action to Prevent Mold

1 – When you see water or moisture act quickly

– Check home foundation, walls, windows, roof, plumbing, tubs and sinks for water leaks.  If you find a leak or a spill, dry the area and fix the leak

– Check window sills regularly for condensation or moisture, particularly during the cold months.  If found, act quickly to dry the wet surface

2 – Ventilate your home

3 – Keep your home warm and ensure good air circulation

4 – Remove items that may cause mold

5 – Keep your home clean and dry

6 – Minimize other indoor moisture sources

7 – Prevent water from entering your home

In regards to your home’s exterior, we recommend the following for helping to prevent or eliminate mold problems:

– Regularly check the condition of the roof and exterior finish for any places where water might enter

– Make sure that eavestroughs and downspouts are connected and working properly and that they are free of debris

– Install downspout extensions to lead water away from the building

– Deal promptly with any problems that you find

“Mold in housing is one of the issues that can impact your health and your family’s health.  Yes, where there’s a lot of mold in a home, it’s not a simple problem to address and usually requires professional help.  However, everyone has a role to play in preventing mold and understanding what to do to clean up small areas and how to get help with larger areas.  Even the little things you do can help your health!”
Dr. Thomas Dignan, Health Canada


Sources of Information:

CMHC Article – About Your House: Fighting Mold – The Homeowner’s Guide

Health Canada Article – Mold and Your Health

Solplan Review – September 1995 Issue

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