Fighting Mold-The Homeowner’s Guide

 Understanding Mold

  • Mold can be harmful or helpful — depending on where it grows.
  • Mold needs moisture to grow.
  • Mold 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 adapted to grow and reproduce rapidly, producing spores and mycelia in the process.

You encounter mold every day. Foods spoil because of mold. Leaves decay and pieces of wood lying on the ground rot due to mold. That fuzzy black growth on wet window sills is mold. Paper or fabrics stored in a damp place get a musty smell that is due to the action of molds.

Molds can be useful to people. The drug penicillin is obtained from a specific type of mold. Some foods and beverages are made by the actions of molds. The good kinds of molds are selected and grown in a controlled fashion.

Molds are undesirable when they grow where we don’t want them, such as in homes. Over 270 species of mold have been identified as living in Canadian homes. Molds that grow inside may be different from the ones found outdoors.

What makes molds grow?

Molds will grow if we provide them with moisture and nutrients. If we keep things dry, molds do not grow.

High moisture levels can be the result of water coming in from the outside, through the floor, walls or roof; or from plumbing leaks; or moisture produced by the people living in the home, through daily activities like bathing, washing clothes or cooking. Water enters the building when there is a weakness or failure in the structure. Moisture accumulates within the home when there is not enough ventilation to expel that moisture.

Different kinds of molds grow on different materials. Certain kinds of molds like an extremely wet environment. Other kinds of molds may be growing even if no water can be seen. Dampness inside the material can be enough to allow them to grow.

Why are molds a concern?

Damage to materials is one concern. Materials get stained or discoloured, and over time they are ruined. Moldy paper and cardboard disintegrate over time. Fabrics are damaged. Continued mold growth can be indicative of moisture conditions favourable for growth of fungi that cause wood rot and structural damage.

When molds are growing inside the home, there may be health concerns. Molds release chemicals and spores.

Health experts indicate that, depending on the type of mold present in a home, the amount and degree of exposure, and the health condition of the occupant, the health effects of mold can range from being insignificant to causing allergic reactions and illness.

Pregnant women, infants, the elderly and those with health problems, such as respiratory disease or a weakened immune system, are more at risk when exposed to mold. Consult your family physician if you believe there is someone who may be at risk.

Is there a mold problem?

Molds are always found in the air outside and in all buildings. They come into the home in many ways — through open windows or doors, on clothing, pets, food or furniture. The problem starts when mold grows inside the home.

Some mold growing, for example on the window sill but not elsewhere, is not a cause of concern. You can clean the mold yourself. The presence of mold is a sign that there is too much moisture in your home — a situation which must be corrected.

Inspect the home to find the extent of the mold.

How can you tell if it is mold?

Discoloration

Discoloration is a sign of mold. However, all discoloration is not due to mold. Carpeting near baseboards, for example, can be stained by outdoor pollution entering the home. Stains or soot may also be caused by the smoke from burning candles or cigarettes.

Mold may be any colour: black, white, red, orange, yellow, blue or violet. Dab a drop of household bleach onto a suspected spot. If the stain loses its colour or disappears, it may be mold. If there is no change, it probably isn’t mold.

Smell/Odour

Sometimes molds are hidden and cannot be seen. A musty or earthy smell often indicates the presence of molds. But a smell may not be present for all molds. Even when you don’t notice a smell, wet spots, dampness or evidence of a water leak are indications of moisture problems and mold may follow.

How much mold is growing?

One way to know is to estimate the area of the 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. Clean up small areas yourself using a detergent solution, household rubber gloves and a dust mask for protection. Refer toHow to clean-up small problems for the procedure.

Small moldy areas in homes may become larger over time, if ignored, so it’s important to clean up and remove even small patches of mold.

The mold area is considered “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 metres (size of a 4 x 8 foot sheet of plywood). Assessment by a professional is recommended. You can clean up moderate amounts of mold but you must follow the proper procedures and use the proper protective equipment. Refer to Moderate area clean-up for the procedure.

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 of mold yourself. You need professional help to determine why the mold is there in the first place and how to clean it up.

When should you seek professional help?

You may need professional help when:

  • There is a lot of mold
  • The home is very damp and moist
  • Mold comes back after repeated cleaning
  • A family member suffers from asthma or respiratory problems or other health problems that appear to be aggravated inside the home

How do you get professional help?

Contact your local CMHC office for a list of individuals who have completed the CMHC Residential Indoor Air Quality Investigator program. A trained IAQ investigator, who operates a private business and sells his/her services, examines the indoor air quality of your home and documents your concerns. He/she identifies the problems, finds their sources and suggests solutions in a written report. Recommendations are provided to you in an action plan that consists of various options to improve the indoor air quality in your home.