Understanding Mould Growth
Mould is a naturally occurring organism that plays an important role in outdoor ecosystems — breaking down organic matter. Inside your home, however, mould growth is a serious problem. It damages structural materials, destroys personal belongings, and poses genuine health risks to everyone living in the affected space.
Mould spores are present in the air virtually everywhere. The reason mould doesn't grow everywhere is that it requires three specific conditions simultaneously: a moisture source, a moderate temperature (typically 20–30°C), and stagnant air. Remove any one of these conditions and mould cannot grow. But in the aftermath of water damage — a burst pipe, a flooding basement, a roof leak — all three conditions are often present, and mould can establish itself within 24–48 hours.
Three Conditions Required for Mould Growth
Moisture
Any source of elevated moisture — standing water, high humidity, condensation, or damp building materials — provides the water mould needs to grow. Addressing the moisture source is the most critical step in any mould remediation.
Moderate Temperature
Most mould species thrive between 20–30°C — the same range that humans find comfortable. This means that simply keeping a space warm does not prevent mould growth; moisture control is what matters.
Stagnant Air
Mould grows best in areas with poor air circulation — inside wall cavities, under floors, in attic spaces, and in corners with limited airflow. Good ventilation reduces mould risk by carrying moisture out of the space.
Health Risks of Mould Exposure
Exposure to mould — particularly in an enclosed living space where you spend significant time — can cause a range of health effects. The severity depends on the type of mould, the concentration of spores, and individual sensitivity (people with asthma, allergies, or compromised immune systems are at significantly higher risk).
Common Health Effects
- Headaches and difficulty concentrating
- Nausea and fatigue
- Respiratory symptoms: coughing, wheezing, shortness of breath
- Nasal and sinus congestion
- Skin and eye irritation
- Aggravation of existing asthma or allergies
Black Mould (Stachybotrys chartarum)
Stachybotrys chartarum — commonly called "black mould" — is a particularly toxic species that grows on high-cellulose materials (drywall, wood) in very wet conditions. It releases mycotoxins that can cause severe respiratory symptoms, neurological effects, and in chronic, high-level exposures, more serious health consequences.
Not all black-coloured mould is Stachybotrys — and not all mould is black. Only laboratory testing can definitively identify mould species. We recommend professional assessment for any significant mould growth.
Mould vs. Mildew — What's the Difference?
Mould and mildew are often confused, but they're distinct organisms requiring different responses:
Mildew
Mildew is a surface fungus — it grows flat on surfaces and appears white, yellow, or grey. It primarily affects plants and organic materials like fabric and paper. While mildew can cause discolouration and mild odours, it generally doesn't penetrate deep into building materials. It can often be addressed with surface cleaning and improved ventilation.
Mould
Mould is three-dimensional — it grows into the structure of the material it colonizes, not just on the surface. It can penetrate drywall, framing lumber, insulation, and subfloors. This is why mould cannot simply be wiped off a surface — the spores and root-like structures (hyphae) remain even after surface cleaning, and the mould will regrow. Professional remediation physically removes or encapsulates affected material.
Warning Signs You May Have a Mould Problem
Visual Signs
- Dark spots (black, green, grey, or white) on walls, ceilings, or floors
- Discolouration of grout lines in bathrooms or kitchens
- Staining on ceiling tiles or around ventilation registers
- Peeling, bubbling, or warping of paint or wallpaper
- Visible condensation on windows or cold exterior walls
Non-Visual Signs
- Persistent musty or earthy odour — particularly in basements or bathrooms
- Family members experiencing unexplained respiratory symptoms or headaches that improve when away from home
- Recent water damage that was not professionally dried
- History of flooding, roof leaks, or plumbing failures
- Chronically high indoor humidity (above 60%)
DIY vs. Professional Mould Remediation
Health Canada provides clear guidance: if mould growth covers an area of 3 square metres or more (roughly 10 square feet), professional remediation is recommended. Here's why that guidance exists:
When DIY May Be Appropriate
- Small areas of surface mildew on non-porous materials (tiles, glass, metal)
- Minor mould on the surface of caulking in bathrooms that hasn't penetrated the substrate
- Areas less than 1 square metre that can be fully cleaned and the moisture source permanently fixed
- When you have no health conditions that make mould exposure particularly risky
When Professional Help Is Required
- Mould covering 3+ square metres — Health Canada recommendation
- Any mould inside wall cavities, under flooring, or in HVAC systems
- Mould following sewage backup or black water damage
- Anyone in the household with asthma, allergies, or immune compromise
- Mould that keeps returning after cleaning (indicates moisture source not resolved)
- Suspected black mould (Stachybotrys) requiring testing and specialized protocols
- Mould in HVAC systems — spores will be distributed throughout the entire building
Our Mould Remediation Process
Professional Assessment
We assess the full extent of mould growth — including areas not visible to the naked eye — using moisture meters, thermal imaging, and visual inspection. We identify and document all affected materials and develop a remediation plan including appropriate containment, personal protective equipment levels, and disposal protocols.
Containment
We establish physical containment barriers using polyethylene sheeting to isolate the work area and prevent cross-contamination of unaffected areas. Negative air pressure may be established using HEPA-filtered air scrubbers to ensure that disturbed mould spores are captured rather than spreading throughout the home.
Moisture Source Elimination
Mould remediation without fixing the moisture source is temporary — the mould will return. We identify and address the root cause: whether that's structural drying of water-damaged materials, fixing a plumbing leak, improving ventilation, or sealing a basement against water infiltration.
Remediation
Affected materials are removed or treated using Health Canada approved antimicrobial products and industry-standard protocols. Non-salvageable porous materials (drywall, insulation, carpet) are carefully removed, bagged, and disposed of properly. Structural elements that can be saved are thoroughly cleaned, treated, and verified dry.
Air Quality Verification
Post-remediation air quality testing verifies that mould spore counts have returned to acceptable levels and that the remediation was successful. This documentation is valuable for insurance claims and provides you with confidence that your home is safe.
Reconstruction
Once the mould is fully remediated and moisture levels are normal, we can reconstruct any removed materials — replacing drywall, insulation, flooring, and other building components — restoring your home to its pre-loss condition.