Testing For Mold

By Mike Holmes

Mike’s Advice / Home Safety & Maintenance

Friday, June 15th, 2018 @ 1:03pm
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Every house has some degree of mold and bacteria, no matter how clean it looks. What’s important is to keep the number of mold spores in your home low and prevent these germs from thriving in order to protect your health.

Mold overgrowth – especially when reproductive spores are inhaled—triggers respiratory ailments such as hay fever, nasal allergies and asthma, as well as rashes and eczema when it touches the skin. And if ingested, significant concentrations of toxic bacteria can cause abdominal cramping, diarrhea and fever.

Here’s something to think about. In an airtight home, you must make sure you are properly ventilating and exchanging the air. If the air isn’t properly exchanged through good ventilation you can have poor indoor air quality and moisture problems, since most of the moisture in your home comes from the people living in it. And moisture leads to mold.


  • Hay fever
  • Nasal allergies
  • Asthma
  • Rashes
  • Eczema
  • Abdominal cramping
  • Diarrhea
  • Fever
Mike's advice mould

How Do You Test For Mold?

How do you know if your home has too much moisture? For one, the indoor environment might seem damp or musty, there can be signs of moisture on walls, on the ceiling, in corners and around windows, plus the windows might have some condensation build-up.

Homeowners can also use a moisture meter or hygrometer, which is a digital device that measures air’s water-vapour content. A home’s relative humidity should be within the 30 to 50 percent relative humidity (RH) range. But if you want to know of your home has a mold issue for sure, it’s best is to hire a pro to look for potential moisture issues around your home and possibly test the air.

Some home inspectors offer Indoor Air Quality (IAQ) assessments. During these inspections a home inspector will go through the entire home and identify potential indoor air quality risks, including moisture issues that can lead to mold. They can also take indoor air samples, which are sent to a certified lab for analysis. They can even give you a mold spore count and send you a report with results.

What Does Mold Need To Grow?

Mold needs moisture and food to grow, and unfortunately homes provide the perfect environments for these bacteria to thrive.

Mould feeds off of many building materials found in homes, such as paper, wood and carpeting. Walls are made of wood studs and drywall – both of which will grow mold. Because these materials are so prevalent in homes it is difficult to eliminate them entirely. Instead homeowners must control moisture levels to prevent mold growth.

How Do You Remove Mold?

Getting rid of mold-producing germs and bacteria is impossible – they’re everywhere. Your best defence against mould is to prevent these spores and bacteria from growing in your home.

To do this, remove excess moisture and humidity from your home through proper ventilation, especially in traditionally damp areas, such as the basement, bathrooms, laundry room and kitchen. You can also prevent moisture from entering your home through weaknesses in the building envelope, such as flashing, caulking, rotted framing around windows, cracks in the foundation or a roof leak.


If you only see a bit of mould but feel sick, you might have a bigger problem than you think. Your best bet is to call a pro and don’t attempt your own clean-up!


Mould common areas

  1. Attic
  2. Ceilings, ceiling tiles, as well as in corners
  3. Drywall
  4. Wall cavities
  5. Ductwork
  6. Around windows & windowsills
  7. HVAC systems
  8. Masonry surfaces
  9. Sump pump & drains
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