Preventing Mould in Your Home
Learn more about mould and the essential steps to preventing it and protecting your health.
Mould is a common issue that we encounter in our daily lives. It can appear in various areas of your home and poses significant health risks when it grows indoors. Addressing and preventing mould is essential to maintaining a healthy indoor environment.
Understanding Mould Growth
Mould requires moisture to grow. Moisture can come from daily activities such as bathing and cooking or from water entering the house through cracks and leaks. When mould grows indoors, it may affect air quality and become a health hazard – especially for those with respiratory issues. Tackling a mould problem effectively involves addressing existing mould and preventing future growth.
Causes of Mould
- Mould will grow if it is provided with moisture and nutrients.
- Different kinds of mould grow on different materials, as some kinds of mould like it soaking wet, while others may grow even if no water can be seen.
- Dampness inside a material can be enough for mould to grow.
Identifying Mould
- A musty or earthy smell often means mould growth.
- Beware of wet spots, dampness and signs of a water leak, as moisture problems may lead to mould.
Removing Mould
- You can clean up small areas yourself following the proper steps and using safety precautions.
- Medium and large areas should be cleaned up by people who are professionally trained.
- The best way to clean mould yourself is to use warm water and unscented dishwashing detergent.
Did you know…
Mould removal is an eligible expense through CMHC On-Reserve Residential Rehabilitation Assistance Program.
Resources for Managing and Preventing Mould
Identify, prevent and address mould for a healthier living environment.
Ask an Expert
Experts from across the housing sector to weigh in on the impact of mould.
(Visual: Shots of various residential areas of a large city.)
(Text on-screen: Ask an expert)
0:00:06
JOELLE: How much time do you spend in your home? Is it one of the places you feel safest? That's not the case for a large portion of the population.
(Text on-screen: Joelle Hamilton, Communications & Marketing, CMHC)
0:00:15
JOELLE: According to Canada's 2021 census, people in First Nations communities are four times more likely than the non-Indigenous population to live in crowded housing. This happens when there aren't enough bedrooms for everyone living in the home.
(Text on-screen: People in First Nations communities are: 4 times more likely than the non-Indigenous population to live in crowded housing.)
0:00:25
This happens when there aren't enough bedrooms for everyone living in the home.
(Visual: Shots of a freight truck driving past a “Welcome to Sioux Narrows” sign and of houses located on a waterfront.)
(Text on-screen : Mould’s impact on First Nations Communities)
0:00:33
JOELLE: People in First Nations communities are six times more likely to live in homes needing major repairs.
(Text on-screen: People in First Nations communities are: 6 times more likely to live in housing in need of major repairs.)
0:00:40
JOELLE: Major repairs are the work needed to fix issues with plumbing, wiring, walls, floors and ceilings.
(Text on-screen: Major repairs: plumbing, wiring, walls, floors, ceilings)
0:00:48
JOELLE: Poor-quality housing can lead to significant issues, including mould, a long-standing health hazard in First Nations homes.
(Visual: Shots of mould built up in a bathroom, on the border of a window and around a ventilation hatch located on a ceiling.)
0:00:57
BLANCHE: Environmental public health officers conduct health assessments of homes in First Nation communities and in different types of housing units, and mould is a problem that we commonly see during some of those inspections.
(Text on-screen: Blanche Dussault, Environmental Public Health Officer, Indigenous Services Canada)
(Visual: Shots of an expert discussing with a resident and of a device designed to prevent the build-up of mould.)
0:01:09
BLANCHE: Personally, I've seen mould in very different contexts, such as in a basement following a really bad flood or developing through very subtle condensation issues in the building envelope.
(Visual: A First Nation resident and a building expert inspect the moisture around a dryer exhaust vent on the exterior wall of a house. Two agents inspect the foundations of a house and discover mould.) Un résident et un expert inspectent la moisissure installée autour d’un évent de sécheuse à l’extérieur d’une maison. Deux agents inspectent les fondations d’une maison et y trouvent de la moisissure.)
0:01:21
DON: There used to be a number of houses with mould issues, including my house. But there are houses that it's just a recurring problem, when they clean it up and it is just back again in a few days.
(Visual: Shots of a golden field located near two houses and of a house located near a “Welcome to Windigo Island” sign.)
(Text on-screen: Don Kavanaugh, Council Member, Animakee Wa Zhing #37 First Nation)
0:01:36
DON: I guess the challenge is not knowing where mould comes from. Not knowing how it grows, where it comes from, what the problems are, what to look for.
(Visual: Shots of the exterior of a house and of mould having set in the foundations, under the gutter pipe.)
0:01:46
DON: If you don't know where the problem originates, then you don't know where mould comes from.
(Visual: Shots of mould having set on the exterior wall of a house and on the border of a window, followed by an exterior view of a house located near a waterfront.)
(Text on-screen : How to Spot Mould)
0:01:54
JOELLE: Mould thrives in moist and humid places. Spotting mould in your home can sometimes be straightforward, but other times, it's much more challenging.
0:02:04
JOELLE: Mould can be in plain sight, like on walls or ceilings, making it easy to detect. However, it can also hide in less obvious places such as behind walls, under carpets and basement floorboards, or in your HVAC system, where it's much harder to find.
(Text on-screen: Where can mould grow? Drywall, wood, ceiling tiles, wallpaper, carpets, wall cavities, basement subfloors, crawl spaces)
(Visual: Shots of feet applying pressure on a carpet, of an electric heater and of mould having set in on an exterior wall, around a dryer exhaust vent.)
0:02:20
JOELLE: Let's hear from experts who will help us understand how to identify mould, both visible and hidden.
(Visual: Shots of a ventilation hatch located on a rooftop and of a window viewed from inside a house.)
0:02:28
CLINTON: You can typically tell if you have a serious mould problem by using your senses. Mould can be any colour, but visually, it will typically have a fuzzy or chalky appearance.
(Text on-screen: Clinton Sutton, Building Science Consultant, CMHC)
0:02:37
CLINTON: You may notice little spots are starting to grow and expand on interior surfaces, such as interior finishes, dry walls, furniture and even your clothing.
(Visual: Shots of large spots of mould having set in on a ceiling, followed by a laundry room where a large amount of clothes are piled up.)
0:02:46
CLINTON: You may notice that your paint may begin to blister in areas of the house that have higher moisture content. You may notice that there's a very musty odour within the house and your nose may begin to tingle.
(Visual: Shots of mould having built up on the ceiling of a bathroom.)
0:02:59
CLINTON: You may have brain fog or headaches for no reason, and maybe even your animals may begin to act a little different.
0:03:07
CLINTON: There may have been a recent water event that you're aware of, where there is an ingress of water or a flood, and some materials in the house that didn’t get wet are still there and may need to be removed.
(Visual: Exterior shots of rain droplets falling from a rooftop, of water accumulated under the foundations of a house and of mould having built up in an unspecified location.)
(Text on-screen : Early intervention and proactive measures)
0:03:20
JOELLE: Early intervention and proactive measures are crucial in tackling mould. Let's hear from experts who are actively addressing mould in First Nations housing.
0:03:30
BLANCHE: If you find mould in your home, the first thing you want to do is to promptly assess the situation. So, you'll want to find out what the extent of the issue is and then, think about the potential sources of water creating the mould.
(Visual: A house is viewed from the outside while snow is falling.)
0:03:43
BLANCHE: Then, you'll want to protect yourself. So, if the area is small enough to clean yourself, you'll have to wear some gloves, some protective eyewear, and an N95 respirator.
(Visual: Shots of water dripping from a gardening hose and of a person cleaning a chemical cartridge respirator mask.
0:03:54
BLANCHE: If the area is too big, then you'll want to isolate the area to prevent spores from traveling to other parts of your home.
(Visual: Shots of a person picking up an N95 mask, followed by mould having built up on the exterior wall of a house.)
0:04:01
BLANCHE: You'll also want to refer to your community's health department and/or housing department, because they'll give you useful information as to how to correctly and safely remove the mould from the affected surfaces.
(Visual : Shots of mould having set on the border of a broken window patched with tape, followed a window frame.)
0:04:15
BLANCHE: The key to controlling mould is moisture control. So, you’ll want to keep your house dry, free from leaks, and improve the ventilation in your home.
(Text on-screen: About RRAP)
0:04:27
JOELLE: Now, let's learn about CMHC's Residential Rehabilitation Assistance Program.
0:04:34
CLINTON: First Nation communities can access funding for mould remediation through our Residential Rehabilitation Assistance Program, or RRAP.
0:04:40
The RRAP Program must list all remediations required to ensure that the house meets a minimum health and safety requirement.
(Visual: Shots of a First Nation reserve viewed from the water and of a house located near a children’s playground.)
0:04:49
CLINTON: Once a qualifying repair has been listed, mandatory eligible repairs may be pursued.
(Visual: Shots of a person perusing the maintenance instructions of a ventilation unit, followed by the same instructions fixed on a wall.)
(Text on-screen: Tips for mould prevention)
0:04:55
JOELLE: We've all heard the old adage “an ounce of prevention is worth a pound of cure”. This can't be truer when it comes to preventing mould.
0:05:05
CULLEN: If a new construction is done properly, mould shouldn't be an issue unless there's a problem within the home and the occupants and how they're living.
(Text on-screen: Cullen Robb, Technical Services Advisor, Anishinaabeg of Kabapikotawangag Resource Council)
0:05:14
CULLEN: Also, we'd want to look at why the mould is growing, what's causing it to grow. Because you can get rid of the mould, but if the problem is not fixed, it's just going to come right back.
(Visual: Shots of a house under construction and of various solar panels observed from afar, from the water. Two workers enter the wooden framework of the house.)
0:05:24
CULLEN: When a house gets started, before it's constructed, a set of plans are produced, specify how the house is to be built, and there are key stages that homes get inspected.
(Text on-screen: Mould in Housing. Foundation. Choose a well-drained building site. Slope grading away from the foundation to divert water away from foundation walls. Seal and insulate the foundation to keep the basement warm and dry.)
(Visual: Shots of a table saw, of house flooring laid out on the ground and of the interior of a house’s foundations.)
0:05:35
CULLEN: For example, we come and look at the site. We look at the foundations prior to concrete being poured. We look at the framing, the installation of the insulation, the vapour barrier and the air barrier systems, plumbing, mechanical…
(Text on-screen: Roof and Attic. Replace old shingles, flashings and drip edges. Insulate and seal air leakage points between the house and attic. Use raised heel trusses to provide sufficient space for full attic insulation over the exterior walls.)
(Text on-screen: Interior. Install quiet, energy efficient exhaust and controls. Install a heat recovery ventilation system. Choose durable materials that are moisture resistant and easy to clean.
(Visual: In the background of the on-screen texts, shots of wooden beams and of the framework of a house under construction, of a worker at word and of a large plywood board laid out vertically.)
0:05:49
CULLEN: It's the inspector’s role, as well as the people installing some of the mechanical equipment, because the homeowner has no idea how, sometimes, these systems work.
(Text on-screen: Windows and doors. Choose energy-efficient windows to avoid condensation build-up. Install moisture-resistant vinyl, fiberglass or metal clad window frames. Replace weatherstripping to seal windows and doors properly.)
(Visual: In the background of the displayed text, shots of a worker applying sand around the foundations of a house.)
0:05:59
CULLEN: So, it's important that, before they move in, you take them there and you show them… You know, this is what this piece of equipment does, this is how it works, this is how you clean and maintain it.
(Visual: Shots of wooden boards and various debris dispersed around a house under construction, followed by a worker operating the table saw.)
(Text on-screen: A Collective Approach)
0:06:12
BLANCHE: A healthy home is crucial for the mental, physical, psychological and emotional well-being of the occupants. Mould is only one part of having a healthy environment. And when people have a mould-free home that is dry and well-ventilated and well-maintained, they can regain confidence in the safety of their homes, and that can lead to more positive health outcomes for families.
(Visual: Shots of a young child standing in a baby jumper toy, followed by the words “Smile, Share, Live, Love” stuck to a refrigerator.)
0:06:21
BLANCHE: Mould is only one part of having a healthy environment. And when people have a mould-free home that is dry and well-ventilated and well-maintained, they can regain confidence in the safety of their homes, and that can lead to more positive health outcomes for families.
(Visual: Shots of traditional First Nation baked good being prepared, followed by an expert finishing up the installation of a ventilation device.)
0:06:37
BLANCHE: And we try to work with the population to give them the tools and the knowledge necessary to control mould in their homes and, hopefully, allow them to regain ownership of their health and their environment, and we hope that we can see this cascade towards greater community well-being overall.
(Visual: Shots of a First Nation reserve located near a road, of a community gathering where meals are being cooked outside, and of a family resting in their living room.)
0:06:56
CLINTON: At the end of the day, the occupants want a safe place to put their head at night and we want everyone to have a safe place to stay.
0:07:03
DON: I wish for my community that it's eradicated, that it doesn't exist in the future.
0:07:09
DON: It’s not really any individual's responsibility to look after the housing in our community. It's a community thing.
0:07:17
CULLEN: I think it's everybody's role to prevent mould, to a certain extent. The homeowner has to understand what causes mould growth and some of the things that can lead to that.
(Visual: Shots of a house under construction viewed from afar and of workers on duty on the roof of a building, followed by an expert talking to a worker.)
0:07:28
CULLEN: I really believe that healthy homes lead to healthy lives.
0:07:32
JOELLE: We need a coordinated approach to address mould in First Nations housing. Identification, prevention and awareness are the most important tools at our disposal.
0:07:43
JOELLE: By identifying mould, families can be aware of when professionals should be called in to assist in cleanup or determine why moisture is building up in their home.
(Visual: Shots of two building inspectors searching for mould under the foundations of a house, followed by mould having built up on a floor and on the lower part of walls inside a house.)
0:07:53
JOELLE: To prevent mould, we can renovate or design and build homes that limit its spread. Help raise awareness about mould by sharing this video.
(Visual: Shots of houses in various stages of construction, viewed from afar and from the air.)
0:08:03
JOELLE: Together, we can work towards making homes safer for everyone.
(Text on-screen: Subscribe on YouTube)
(Visual: Animated logos of the CMHC and the Government of Canada)
4 STEPS TO PREVENTING MOULD AFTER FLOOD
Flood Cleanup and Mould Prevention
Learn the 4 essential steps to protect your home and health after a flood.
Floods are one of the most common and costly natural disasters in Canada. Flood damage is also a major cause of mould in homes, which can make you and your family sick.
1. Preparing for the flood cleanup
- Gather all the equipment and supplies you might need for the flood cleanup, including:
- disposable gloves
- N95 masks
- rubber boots
- goggles
- pails, mops and sponges
- plastic garbage bags
- unscented detergent
- clean water
- Where possible, open windows and doors to provide fresh air.
- Rent any larger equipment you might need, including submersible pumps, fans, wet/dry shop vacuums and dehumidifiers.
2. Remove water, mud and other debris
- Remove standing water with pumps or pails, then with a wet/dry shop vacuum.
- Remove all soaked and dirty materials, as well as debris, and residual mud and soil.
- Clean dirty walls and furnishings with unscented soap and water, then dry them with a wet/dry shop vacuum.
- Clean and dry all floors as quickly as possible.
3. Dispose of wet materials that can't dry within 48 hours.
- Remove and discard flooring that has been soaked by flood water.
- Remove all wet drywall, going at least 30 cm above the flood water level.
- Dispose of all wet items that do not dry quickly, including:
- insulation and drywall
- carpets
- particleboard furniture
- mattresses and box springs
- stuffed toys
- pillows and cushions
- furniture coverings
4. Clean and dry out your home and salvageable possessions
- After cleaning with soap and water, use fans, heaters and dehumidifiers to speed up the drying process. Rapid drying is essential for mould prevention.
- Vacuum dry surfaces and surfaces that weren’t directly affected by flood water with a HEPA vacuum cleaner.
During flood cleanup, think safety first!
Flood cleanup has 2 immediate dangers: electric shock and sewage contamination.
1. Electric shock
You can avoid electric shock by always wearing rubber boots when standing in water. You should also shut off the power to the flooded area at the breaker box. Be sure to keep all extension cords out of the water, too.
If you’re not sure what to do, don’t be afraid to ask your local electricity utility for help.
2. Sewage contamination
If your house is flooded by sewage-contaminated water, you’ll need to take several special precautions.
It’s very easy to get infected by disease handling sewage-contaminated water and materials. You may even be in danger of infection just by breathing the air in an area contaminated by sewage. If you suspect sewage contamination, you should:
- contact your environmental health officer or community health representative
- avoid exposing family members and pets to the contaminated area
- keep children, pregnant women and people with respiratory problems away from contaminated water and materials
- bag, tag and dispose of contaminated household items according to your local regulations
Once the contaminated items and standing water are removed, you’ll need to do a thorough cleaning of the entire area.
Occupants’ Manual
Essential information for home occupants and anyone interested in learning the basics about mould, including a home inspection checklist.
Housing Providers’ Manual
Discover detailed information and essential training for addressing mould issues, tailored for technical service providers and housing managers.
Mould in housing infographic
Information for builders and renovators – stop mould before it starts.
Mould cleanup infographic
Follow these simple steps to effectively remove mould from your home.
Mould Prevention Webinar by FNNBOA
A webinar for builders and renovators providing key principles to help First Nations communities reduce moisture and prevent mould in homes.
Get in Touch
For more information about this program, please contact your Indigenous and Northern Housing Solutions Specialist.