There are thousands of different known mold species present in the world today. There is one species, however, that dominates the headlines: black mold. This species drives one of our most common questions: how do I detect mold in my house?
“Toxic black mold” actually refers to a species of mold called Stachybotrys chartarum. This mold species has a potential for releasing mycotoxins (harmful compounds produced by mold). This is the species that most homeowner believe they have in their home.
But, did you know that Stachybotrys chartarum isn’t always black in color? That’s right. It can be gray, green, slimy or powdery. The color of the mold doesn’t always dictate the species. In fact, there are hundred of black-colored mold species that are not toxigenic.
One fact is true: all molds – regardless of their color or species – carry the potential to cause harmful reactions. It happens especially to those with compromised immune systems, or with pre-existing respiratory conditions, or allergies.
If you’ve noticed persistent coughing, sneezing, or other flu-like symptoms while indoors, hidden mold could be one of the reasons.
Under the right conditions mold can grow within 24 to 48 hours. Homes with poor ventilation, elevated humidity, or moisture intrusions are much more susceptible to hidden mold growth issues. Therefore, in this homeowner’s guide, we’ll provide you with practical ways on how to detect mold in your house, even if it’s not visible to the naked eye.
Recently, a study found that many First Nation homes on Ontario reserves had mold spores that went undetected due to the lack of professional mold inspection.
Mold can be an issue for occupants if left undetected. However, many homeowners in Canada are not aware of hidden mold that may be present inside their property.Â
For instance, a 2018 survey shows that 5% of Canadians have patches of mold greater than one square meter inside their home.
Even in our neighboring America, a whopping 47% of homes have mold or some form of dampness.Â
How do you know if you are at risk of being exposed to hidden mold? Well, read on below as our team has compiled 10 proven ways to detect mold in your house.
Now, this may seem like an obvious one, but you would be surprised how often we find visible signs of mold growth in a home, and the owners were completely unaware. We get it though. Sometimes, it’s not always clear what is, or isn’t mold.
Visible discolorations that can be mold include patchy, circular growth patterns on walls. They also look like speckled, dust-like patterns on window sills. Mold can be fuzzy, powdery, slimy and everything else in between.
A good tip is to look in areas that are prone to moisture, such as bathrooms, basements and attics. Mold can be black, green, gray, white, purple, yellow, pink, and more. The colors will depend on the species, its food source and the moisture content present.
A telltale sign that mold may be present in your home is that famous “musty odor” that most of our clients report.
These musty odors are mostly caused by 2 things: moisture and mold.
Mold produces microbial volatile organic compounds (MVOCs), which are gases released by mold as it grows and metabolizes.
Moisture can also cause these odors as they foster conditions conducive to mold growth, accelerate decay of organic materials, and increase levels of relative humidity – all of which will impact how your house smells.
So, if you or your guests start to comment on a musty, earthy, or damp odor in your home, don’t ignore it. It can be an indicator that hidden mold is growing.
Moisture is the problem; mold is a symptom.
Most of our clients are shocked to learn that it can take less than 72 hours for mold to develop following a moisture intrusion. Moreover, common sources include poor drainage along the exterior.
For instance, a good mold inspector will check to see if the grading of your home is negatively sloped towards your foundation wall, or if your downspout is not extended out at a minimum of 3 feet. These are common ways for moisture to make its way into your basement.
Consequently, this can saturate organic materials like drywall or framing components, allowing for mold to develop.
Therefore, a good way to detect mold in your home is to find active moisture intrusions. Where there is water, there can be mold.
We know we’re starting to sound like a broken record here, but be on the lookout for signs of water damage along building materials in your home. The water may have dried up, but hidden mold may have already taken root.
Remember, mold is often the symptom of a moisture issue.
A good mold inspector will look for signs of moisture, often by the visual cues it leaves behind.
Often, a mold inspector will make note of bubbling along painted surfaces, soft spots along flooring materials, or yellow-brown circular stains along a ceiling.
Keeping an eye out for signs of active or residual water damage in your home is important. We recommend contacting an indoor environmental professional to properly assess any water damaged area using specialized inspection and sampling equipment to detect hidden mold.
You should inspect your heating, ventilation and air conditioning (HVAC) system regularly to ensure it is in good working condition. Make sure there is no build up of dust, moisture or other contaminants that can impact the overall air quality in your home.
Did you know that mold can grow on dust that settles inside of your air ducts? Without regular cleaning and maintenance, your HVAC system may be pumping spore-containing air throughout the rooms in your house.
Moisture can also build-up in your HVAC system as a result of condensation from air conditioning or a built-in humidifier system. It can also create that musty odor we mentioned above.
It is good practice to change your furnace filters every season, inspect the inside of your unit for signs of moisture like rust, and to ensure all of the components are functioning properly.
Moisture and mold can attract silverfish, earwigs, spiders, ants and other insects into your home. A good tip for detecting hidden mold is to check for signs that insects are present.
Insects, much like us, require moisture to survive and reproduce. They also need to food to survive. Silverfish, for example, will feed on a variety of organic materials, including mold.
It’s logical to deduce that if moisture is making its way into your home from the exterior, such as with a crack in the foundation, or an unsealed vent, insects are also making their way in through a similar pathway.
Finding insects and their by-products when trying to determine if mold is present is an expert-level tip for any homeowner.
Be aware of an increase in insect activity, paired with elevated humidity or musty odors. It may be a sign to call an indoor environmental professional to assess your home before a bigger issue develops.
Carpets and other retentive textiles are notorious for trapping dust, allergens, and mold spores that enter into your property naturally.
Mold spores are fantastic travelers. As microscopic airborne particles, they are easily dispersed through the air and often enter into your home through open windows. They can also “hitch a ride” into your home from pets, clothing and other moldy materials (think, vintage books, as an example).
What goes up, must come down.
These airborne spores will eventually settle and if you have carpets, area rugs or other textiles, they may find a home woven deep within their fabrics. These spores, and other particles, are “kicked” back up into the air after the textiles are disturbed. Spores and other particles can then be inhaled, and contribute to adverse health effects.
When traditional signs of fungal growth are not present, perhaps consider assessing your carpets as a source of hidden mold.
Measuring your home’s relative humidity levels is a good mold detection strategy. As we already learned, mold loves moisture. Without moisture, mold is powerless.
Mold also loves humid environments. In fact, mold will thrive in spaces where relative humidity levels are above 50%. One of the tools that we use during our comprehensive mold assessments is a hygrothermometer, which allows us to instantly measure temperature and relative humidity levels.
If there’s an area in the home that is more humid than others, it can be a good indicator that mold is present.
We calculate humidity by comparing the actual amount of water vapor present in the air to the maximum amount it can hold at a specific temperature. It is usually in percentage. Relative humidity indicates how saturated the air is with water vapor.
A good, cheap and effective way to determine if your home has conditions conducive to fungal development is buy a hygrometer, and measure the rH (relative humidity) levels. If the rH levels are north of 50%, we recommend improving the ventilation, or installing a dehumidifier to get those levels down.
One of the best tool at your disposal for detecting mold in your home is: YOU
As Canadians, we spend up to 90% of our time indoors – most of which within our own homes.
Trusting your instincts that something is going on inside of your house, even when there’s no visible evidence to support it, is something that we highly encourage.
Over the last decade, we have inspected hundreds and hundreds of homes for mold. You wouldn’t believe how often our clients firmly believed that there was something hidden causing health issues, even though their partner disagreed. This is a common occurrence.
8 times out of 10, they were right! Our assessments picked up on a hidden mold issue that was directly impacting good indoor air quality.
So, if you suspect an issue – if there’s a gut feeling you just can’t shake – run with it. You may be right. Run through the checklists above and if can’t identify the source, look at the next tip below for the ultimate mold detection solution!
Although this may seem like an obvious ploy to hire our company (can’t blame us for trying, right?), it really is the best way to detect mold in your house.
Not only can a professional mold assessment confirm or deny the presence of mold, it can also determine the type and concentrations of mold, especially if paired with air or surface testing.
This data can be invaluable if you are experiencing health symptoms that need to be diagnosed. Simply take the laboratory results to your physician and let them see what you’re breathing in. There may be a correlation between your symptoms and your indoor environment.
Also, mold spores are very small. The average mold spore size is between 2 to 20 µm (micrometers or microns, which is equal to one millionth of a meter). We cannot see mold spores with the naked eye. Only through microscopic analysis can spores be identified, qualified and quantified.
Professional mold inspectors live and breathe (pun intended) mold spores every day. They know exactly what to look for and they have access to cutting-edge tools to help them understand the source(s) of mold growth present.
A reliable mold assessment will include air testing (non-viable spore traps) & surface testing (if visible discoloration is present) with samples analyzed by certified microbiologists at an accredited and reputable laboratory.
The most reliable method for detecting mold in your house is to hire an expert to conduct a professional mold assessment.
Although we encourage every homeowner to follow the tips in our guide above, hiring a professional really is the most reliable and effective way to detect mold in your home.
You can find molds almost anywhere on our planet. It can grow on virtually any organic substrate, providing a moisture source is present. It can grow on wood, drywall, paper, carpet, dust, soil and food.
Depending on the current life cycle the mold in your home is at, visible signs may not be present and you may not be able to detect it yourself.
Indoor environmental professionals come prepared with calibrated, scientific equipment to collect samples and precise measurements of your indoor space.
This can also include tools like infrared cameras to detect temperature anomalies behind building materials, often revealing unknown moisture intrusions or insulation deficiencies. A good mold inspector looks at the total sum of your indoor environmental data for indicators of current or potential mold growth.
A professional mold assessment should always include a:
Indoor environmental professionals have training to properly capture all of this data and interpret it for you in a way that makes sense. The one thing a professional mold assessment can provide above everything else is peace of mind.
So, if you suspect a mold issue in your home, find a reputable, unbiased mold professional near you and let them do what they do best!
Here are some pro tips for preventing mold growth in your house:
⬡ Thoroughly address any moisture intrusion issue within 24-hours
⬡ Regulated levels of relative humidity to be between 30-50% year round
⬡ Dilution is the solution to pollution. Improve your ventilation with an HRV or air exchanger system.
