Persistent odors, heavy air, black stains creeping into wall corners... These signs often point to a deeper issue: poor ventilation. In Longueuil, a couple who owned an older duplex recently discovered the extent of the damage caused by inadequate ventilation in their semi-finished basement. This service call led to a delicate but successful mission carried out by our ventilation experts at AirGreen.
When Mold Moves In: A Common but Avoidable Case
In this project, we were contacted urgently by the homeowners after a contractor, while renovating a laundry room, discovered large patches of active mold growing on interior walls, along with high humidity levels. Their basement, used as storage and laundry space, had become unsanitary. The air was stale, with no proper circulation, which allowed humidity to settle in permanently.
At AirGreen, we understand that ventilation in basements, often overlooked, is actually crucial for the occupants’ health and the long-term integrity of the building.
A Precise Diagnosis Thanks to Our Expertise
Our technicians performed a complete indoor air quality analysis, measuring:
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Relative humidity (consistently above 70%)
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Air exchange rate
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Surface temperature of the walls
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Air stagnation zones
Result: the basement was completely lacking any mechanical ventilation system. Ventilation relied solely on a partially blocked window and an old, inefficient dehumidifier.
Proposed Solution: Mechanical Ventilation System with Heat Recovery
To address the issue effectively, we recommended and installed a high-efficiency air exchanger: the Venmar AVS® N Series, a model well-suited for smaller residences and semi-subterranean spaces like this one. This system provides:
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Continuous air renewal
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Heat recovery (enthalpic core exchanger)
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Filtration of incoming air
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Targeted extraction of humid, stale air
Model installed: Venmar AVS N120E
Maximum airflow: 120 CFM
Sensible efficiency at 0°C: 65%
Certification: ENERGY STAR®
Eligible for LogisVert grants: Yes (up to $450)
Installation Tailored to the Existing Structure
The biggest challenge of this installation was integrating the ductwork into an existing structure without disrupting finished spaces. We opted for:
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Insulated flexible ducts, routed behind wall panels
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A discreet wall-mounted unit installed in a technical corner of the basement
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Exhaust grilles in the laundry room and bathroom
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Fresh air grilles in the basement’s living area and main hallway
The job was completed over two days, with close coordination alongside the client's finishing work.
Results Observed After Installation
Within the first 48 hours, the homeowners reported:
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A noticeable improvement in air quality (no more damp smells)
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A drop in relative humidity, stabilized around 50%
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Better overall thermal comfort
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And most importantly, complete halt of mold progression
The basement now benefits from consistent, controlled, and effective ventilation.
Why Choose AirGreen for Your Ventilation Projects in Longueuil?
At AirGreen, we’ve completed hundreds of mechanical ventilation system installations in Longueuil, Montréal, Laval, South Shore, and North Shore. Every building is unique, and we tailor our solutions to real-world conditions, including:
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Older homes with fragile structures
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Poorly insulated or unventilated buildings
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Renovated properties where the work must remain discreet
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Primary residences or rental units
Our work stands out because of:
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Extensive technical expertise
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Knowledge of local HVAC regulations
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Personalized support
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And maximum grants, handled entirely by our team
The Risks of Neglecting Ventilation
We’ve seen too many cases where poor ventilation results in:
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Premature material degradation
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Respiratory health issues (asthma, allergies)
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Major renovation costs
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Disputes with tenants or insurance companies
Installing a mechanical ventilation system (HRV/ERV) isn’t a luxury — it’s an essential preventive measure for any property owner.
Available Grants for Residential Ventilation
Good news for residents of Longueuil and the South Shore: Hydro-Québec and the LogisVert program offer grants up to $500 for ENERGY STAR® certified air exchanger installations. Our team handles everything:
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Verifying your eligibility
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Completing all necessary paperwork
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Deducting the grant from your final invoice whenever possible
Conclusion: Ventilation Is the Key to a Healthy Basement
The service call in Longueuil is a perfect example of how valuable a well-designed mechanical ventilation system can be. Thanks to a thorough assessment, careful installation, and personalized follow-up, we were able to preserve the building’s structure, safeguard the occupants’ health, and protect the property’s long-term value.
At AirGreen, we turn humid basements into healthy, comfortable spaces, and we do it with precision, efficiency, and true passion for our trade.