Home » Ventilation Service | Montreal, Laval, Longueuil, South Shore and North Shore » When a Simple Ventilation Check on the North Shore Uncovered a Hidden Infestation
Quand une simple vérification de ventilation à la Rive Nord a révélé une infestation cachée
Reading time: 5'

When a Simple Ventilation Check on the North Shore Uncovered a Hidden Infestation

A residential building on the North Shore faced with persistent discomfort

In a condominium building located on the North Shore of Montréal, several residents in a six-unit property had begun noticing unexplained signs of discomfort: persistent musty odours, strange noises in the ducts, and chronic allergies among some of the occupants, particularly children.

One concerned co-owner took the initiative to contact AirGreen for a preventive inspection of the ventilation system, assuming it was just a dust buildup. What they didn’t realize was that this routine check would reveal a full-blown animal infestation that had been lurking in the ductwork for several months.

Initial inspection: airflow anomalies and suspicious visual signs

From the start of the intervention, our technicians identified several red flags:

  • Ventilation vents clogged with unidentified fibrous material

  • Reduced airflow in certain zones

  • A foul odour emanating from the mechanical room

Using a robotic inspection camera, we explored the horizontal ventilation ducts. To our surprise, we discovered well-established rodent nests, made of insulation wool, debris, stored food, and even bits of plastic. In some areas, mouse droppings were visible, along with scratch marks on the metal duct walls.

Root of the problem: an old unused HRV and poorly maintained ducts

A complete system assessment revealed several factors that had enabled this stealthy infestation:

  • An early-2000s Venmar HRV, out of service for months and accessible from the outside through a poorly sealed opening

  • Uninsulated horizontal ducts in the crawl space, creating a temperate environment ideal for nesting

  • No HVAC maintenance in over seven years

  • Broken exterior air intake grilles, allowing small animals easy access

This situation, far from uncommon, posed a serious health risk to the occupants: suspended particles, bacterial proliferation, contaminated breathable air, and severe allergic reactions, especially in asthmatic children.

AirGreen’s immediate response: decontamination, replacement, and full system sealing

Given the sanitary urgency, we proposed a three-phase intervention plan, approved by the building’s condo board.

  1. Complete removal of nests and duct disinfection

    • Mechanical extraction of all debris and animal waste

    • HEPA-grade double filtration vacuuming

    • Fogging of a non-toxic fungicidal and bactericidal disinfectant

  2. Replacement of the central ventilation system

    • Removal of the outdated Venmar HRV

    • Installation of a new Venmar AVS E15 ECM HRV, 160 CFM, ultra-quiet, with MERV-13 filters

    • Insulation of crawl space ducts to prevent humidity and future intrusions

  3. Physical system reinforcement

    • Repaired exterior grilles with certified rodent-proof models

    • Sealing of access points in foundation walls

    • Integration of activity and humidity sensors for proactive monitoring

Results achieved: back to normal, purified air, and peace of mind restored

Less than a week after the intervention, residents immediately noticed the change: total elimination of odours, improved sleep quality, and reduced allergy symptoms in the children. The building manager shared:

“Without AirGreen, we would never have imagined that a ventilation system could hide so many problems. The professionalism and thoroughness of their team were outstanding.”

This case clearly shows how neglected HVAC systems can have severe and invisible consequences, and why preventive inspections are essential.

A more common issue than you might think on the North Shore

The North Shore, with its many residential buildings constructed between the 1980s and 2000s, is full of under-maintained HVAC systems—sometimes completely abandoned. Inactive, poorly insulated, or exposed systems often become ideal entry points for rodents, especially in winter.

At AirGreen, we understand the specific realities of the local housing stock. Our technical expertise and deep knowledge of the area allow us to act quickly with custom solutions for every type of building—whether in Laval, Blainville, Terrebonne, or Saint-Eustache.

Tips to avoid this type of infestation in your HVAC system

Here are the best practices to protect your ventilation system:

  • Have your HRV inspected every 2 to 3 years

  • Replace filters at least every season

  • Regularly check exterior air grilles

  • Listen for unusual sounds: scratching, noises in the ducts, strange odours

  • Always trust certified HVAC technicians like those at AirGreen

Warning signs of a possible infestation:

  • Unexplained reduction in airflow

  • Presence of animal or musty odours

  • Black dust around ventilation vents

  • Unexplained allergic or respiratory symptoms

Conclusion: behind every inspection lies a public health issue

The intervention at this North Shore condominium shows that every HVAC system requires regular attention. The air we breathe passes through ducts that are often invisible—but not harmless. Thanks to this routine check, a potentially serious health situation was prevented, and the residents regained their comfort.

At AirGreen, we don’t just repair machines. We restore air quality and peace of mind, one building at a time.

Do you live on the North Shore? Contact AirGreen for a full ventilation inspection

Are you a homeowner or property manager in Laval, Terrebonne, Blainville, or elsewhere on the North Shore? Concerned about the state of your ventilation? Call our HVAC experts for a thorough inspection. With AirGreen, every duct we inspect brings you one step closer to a healthier environment.

Leave a comment