MOLD: Residential contruction’s 4 letter word

Moisture that created mold under the insulation was discovered during our friend’s recent renovation.

A friend of ours called me over the weekend after they found mold in the home they have been living in for five years.  She was very concerned for the health of her family, and rightly so.  In past blogs I have covered the topic of moisture on windows and in attics, but what happens if the siding installer has not detailed the windows and door properly when installing flashings and weather seals. It appears that after some hail damage repairs a few years ago, due to improper siding details, moisture has been finding its way into the wall cavity in the basement below a north facing door.

     We talked about the repair process.  Step 1.: Locate the source of the moisture and repair the siding to prevent further moisture infiltration.  Step 2.: Dry up the wall cavity. Step 3.: Clean the area affected by mold.  This is where some care and attention should be paid.  There is a health risk during the clean up process, so I have included a terrific article posted on the CMHC website on the issue of MOLD.

Molds are part of a group of microorganisms called fungi that also include mushrooms and yeasts. Molds are familiar to most people as food spoilers on items such as bread or fruit. Molds are nature’s decomposers in the food chain. If allowed to grow inside your house, mold can be a problem.

Mold Problems

Mold can cause:

  • unsightly stains;
  • damage to paints, wood, drywall, ceiling tiles and fabrics;
  • damage to personal items;
  • allergies; and
  • illness.

Some Symptoms

  • discolouration on surfaces such as walls, ceilings, or furnishings
  • stains on carpets
  • mold on drapes and backs of furniture
  • stains on personal items close to affected areas such as storage boxes and clothing
  • musty smells
  • rotting wood


Mold requires high humidity levels to grow. Some molds require condensation to start growing.  To avoid most mold problems, keep materials dry.  If mold is present, clean the affected area as soon as possible, and identify the source of moisture that allowed the mold to grow in that location.

Clean-up Methods

You can clean small areas of mold yourself using an unscented detergent and water. The mold area is considered “small” if there are fewer than three patches, each patch smaller than one (1) square meter. If you have more than three patches or the areas are larger, you need a trained professional to assess your house. You may also need a trained contractor to clean extensive areas of mold.

When cleaning:

  • use household rubber gloves;
  • use a mask, rated N95, capable of filtering fine particles;
  • use protective glasses;
  • rinse well with a clean, wet rag;
  • dry.

Moldy ceiling tiles and carpets should be removed and discarded. Drywall that remains stained after cleaning with detergent and water may need to be removed. Try washing fabrics. If the mold odour or stain persists, discard.  The proper cleaning procedure involves removing the mold. Chemicals, such as bleach and fungicides are not recommended. It is important to remove all mold residues as they can cause allergies or illness.


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