Last fall, a triplex owner in Rosemont called us because one of his tenants was complaining strange smells and excessive dust.
When we inspected the ducts, we found 15 years’ worth of buildup—dust, construction debris from an old renovation, and even traces of mold caused by condensation.
The worst part? The three units shared the same ductwork. Whatever affected one apartment could potentially affect the other two.
Montreal duplexes and triplexes are different from single-family homes. Shared ductwork, older buildings, and wear and tear from multiple tenants—all of these factors create unique challenges for indoor air quality.
Here's what you need to know if you own or manage a multi-unit residential building in Montreal.
Why Montreal duplexes and triplexes Have Specific Needs
Multi-unit buildings operate differently. It's not just a matter of floor space—the entire dynamic of the building changes.
Shared pathways and the spread of contaminants
In many duplexes and triplexes in Montreal, the ventilation ducts are interconnected between the units.
This means that allergens, dust, cooking odors, and even smoke particles can travel from one apartment to another.
According to data from the NADCA (National Air Duct Cleaners Association), professional cleaning can reduce airborne particles by 50 to 70% in a residential system.
In an apartment building, this improvement benefits all tenants at the same time—but conversely, if the ducts are dirty, everyone breathes contaminated air.
The risk of cross-contamination is real. A tenant with pets on the second floor can affect the air quality on the first floor, even if the tenant on the first floor has never owned a cat in their life.
Old Buildings and Winter Condensation
Approximately 40% of the duplexes and triplexes in Montreal were built before 1980.
These buildings often have uninsulated metal ducts that run through cold spaces—basements, crawl spaces, and poorly heated attics.
Quebec winters, with their freeze-thaw cycles, cause condensation to form inside the ducts. This trapped moisture becomes the perfect breeding ground for mold.
Without regular maintenance, these problems get worse year after year. It’s not uncommon to see ducts in buildings in the Plateau or Villeray that have never been cleaned since they were installed in the 1970s.
Is Duct Cleaning Really Necessary? Facts vs. Myths
Let's be honest. The duct cleaning, It's an industry where there's a lot of misinformation and scams.
What Science Confirms
The EPA (Environmental Protection Agency) and the NADCA agree that duct cleaning is useful when there is actual contamination—not as a routine preventive maintenance measure.
When a system is really clogged, cleaning it can improve energy efficiency by 10 to 20%. That means less work for your furnace and your air conditioning.
Cleaning also reduces the risks associated with mold, especially in ducts that have been exposed to moisture.
For dryer ducts In duplexes and triplexes, this is really a matter of fire safety. Lint buildup is a major cause of residential fires.
Common Myths Among Pet Owners
- Myth #1: «You have to clean the ducts every year.» False. For most well-maintained apartment buildings, cleaning every 3 to 5 years is sufficient. Cleaning too often can even cause premature wear on the ducts.
- Myth #2: «I can do it myself with a Shop-Vac.» No. Household vacuum cleaners don't have enough power to dislodge contaminants stuck to the walls. You'll just be stirring up dust without actually cleaning.
- Myth #3: «Cleaning always permanently improves airflow.» Not necessarily. If your ducts are poorly designed or damaged, cleaning them won't improve airflow. It's a design issue, not a dirt problem.
How much does it cost to have the ducts cleaned in a duplex or triplex in Montreal?
The question everyone asks. And it's only natural to want to know where you're going.
Factors influencing price
A duplex or triplex is more complex than a single-family home.
You usually have 20 or more vents—air outlets, air returns, and sometimes separate systems for each floor.
If your units have separate heating and air conditioning systems, that means there are multiple systems to clean. More ducts = more time = higher cost.
Accessibility also plays a huge role. Ducts in a narrow crawl space or a cluttered attic require more work.
Realistic Price Ranges in Montreal
For a typical duplex or triplex in Montreal, expect to pay between 500$ and 1,200$, sometimes more depending on the layout.
Many companies charge between 30$ and 60$ per vent. With 20 to 30 vents in a triplex, do the math.
Be wary of offers priced at 99$ or 149$ for «the entire building.» These prices often hide additional fees or a subpar service that only cleans the main ducts without touching the branch ducts.
At Vortex Air, we provide transparent quotes after a free inspection. You’ll know exactly what’s included before we get started.
Understand the true cost before requesting a quote It helps you avoid unpleasant surprises and pushy salespeople.
How often should the ducts in an apartment building be cleaned?
There's no one-size-fits-all answer, but there are some sensible guidelines.
Realistic Recommendations
For a standard residential duplex or triplex, cleaning every 3 to 5 years is generally sufficient.
However, certain situations require a higher frequency:
- After major renovations (construction dust in the ducts)
- If you have recurring moisture problems in your basement
- When tenants suffer from severe allergies or respiratory problems
If your rental properties have a high turnover rate (new tenants every year), the ducts get dirty faster due to move-ins and different lifestyles.
Signs That Cleaning Is Needed
Are your tenants complaining about lingering odors that keep coming back even after cleaning? This is often related to the vents.
Excessive dust settling everywhere a few days after cleaning? It's probably coming from the ventilation system.
Are respiratory problems appearing or getting worse among several tenants at the same time? It’s worth having the ducts inspected.
Do you see any visible mold around the air vents? That's a warning sign—there are probably more inside.
Standards, Certifications, and Requirements in Quebec
Cleaning ducts isn't just a matter of sweeping them out. There are standards that must be followed.
Why NADCA Standards Are Essential
NADCA has developed cleaning methods that protect your ducts while ensuring a thorough cleaning.
Cleaning done carelessly can damage the ducts—puncturing the metal, disconnecting joints, or even dislodging the interior insulation.
NADCA-certified technicians know how to access ducts, what equipment to use depending on the type of material, and how to verify that the work has been done properly.
At Vortex Air, we are INVC-certified and in the process of obtaining NADCA certification. We follow these protocols for every job, regardless of the building's size.
Responsibilities of Property Owners in Montreal
In Quebec, landlords are required by the Civil Code to provide safe and sanitary housing.
The quality of indoor air is part of this obligation. If a tenant can prove that dirty vents are harmful to their health, you could be in trouble.
Complaints to the Housing Authority regarding mold and poor air quality are increasing every year. Keep records of the maintenance of your ventilation systems protects you.
It is not yet mandatory to clean your ducts at regular intervals in Quebec, but it is your responsibility to maintain a healthy environment.
Common Problems in Montreal Duplexes and Triplexes
We're seeing the same problems cropping up again in the region's apartment buildings.
Mold, Humidity and Tenants' Health
Mold in the ducts is insidious. It grows in dark, damp places, and its spores spread into the air your tenants breathe.
It is particularly dangerous for people with asthma, young children, and the elderly.
Based on local trends observed in the air quality sector in Montreal, approximately 27% of service requests related to mold come from multi-unit residential buildings.
Winter condensation in poorly insulated ducts is the main cause. Combined with a lack of ventilation, this creates the perfect environment for mold.
Parasites, lint, and backflow
Dirty ducts attract pests. Cockroaches have even been found living in the return air ducts of a duplex in Hochelaga.
Poorly ventilated dryers are a major problem in triplexes. If the dryer vent is shared or too long, lint builds up and creates a real fire hazard.
Odors from one apartment to another—such as cooking smells, tobacco smoke, and household cleaning products—often travel through shared ducts. This creates tension among tenants.
How Is a Professional Duct Cleaning (Multi-Unit) Performed?
Proper cleaning isn't just about blowing air into the ducts and hoping the dust comes out.
Key Steps for Proper Cleaning
- Complete inspection We always start by inspecting the system with a camera, if necessary. This allows us to see the actual condition of the pipes and identify problem areas.
- Powerful suction We use an industrial HEPA vacuum cleaner that creates negative pressure in the system. All dust and contaminants are sucked directly into a filtration unit—nothing is released into the house.
- Mechanical brushing Rotating brushes and pneumatic whips are inserted into each section of the duct to dislodge deposits stuck to the walls. This step is what really makes the difference.
- Final Check The ducts are visually inspected after cleaning to confirm that everything has been removed. The system is also tested to ensure that it is functioning properly.
- See what a proper cleaning looks like helps you tell the difference between legitimate companies and scammers.
Why Choose Vortex Air Ventilation for a Duplex or Triplex
Cleaning the ducts in a multi-unit residential building requires experience and a tailored approach.
Local expertise tailored to multi-unit residential buildings
We've been working on duplexes and triplexes in Montreal for over 10 years. We're familiar with the typical layouts of buildings in the Plateau, Rosemont, Villeray, and the surrounding neighborhoods.
Our team of more than five INVC-certified technicians understands the specific challenges of shared ducts, older buildings, and complex systems.
We are in the process of obtaining NADCA certification, which confirms our commitment to industry best practices.
With more than 500 satisfied clients in the Montreal area, we have the experience to manage any type of multi-unit residential property.
A Human and Transparent Approach
Before we sell you anything, we'll do a free inspection. We'll show you exactly what condition your ducts are in.
If your ducts are clean and don't need cleaning, we'll let you know. We don't pressure you into buying a service you don't need.
Mohamed and Omar, our co-owners, personally oversee the work. You speak directly with the people doing the work, not with a call center on the other side of the country.
We work 7 days a week, from 7 a.m. to 9 p.m., to accommodate your schedule and minimize disruption to your tenants.
Request a free inspection of your duplex or triplex, it means finding out exactly what's going on inside your ducts with no obligation.
Call us at 514-214-7492 or visit vortexair.ca.
FAQ — Duct Cleaning for Duplexes and Triplexes in Montreal
Who pays for cleaning: the landlord or the tenant?
This is the landlord's responsibility. Maintaining ventilation systems is one of your obligations, just like maintaining the heating or plumbing systems.
You cannot legally pass this cost on to tenants, and it’s in your best interest to do so—clean vents reduce your heating costs and prevent complaints.
Can we clean one apartment at a time?
Technically, no—not if the ducts are interconnected.
Even if you clean the vents in just one unit, contaminants in the shared ducts will continue to circulate throughout the building.
For effective cleaning, the entire system must be cleaned at the same time. However, the work can be scheduled to minimize disruption to each tenant.
Does cleaning get rid of mold?
Cleaning removes mold spores and visible buildup from the ducts.
However, if the source of moisture isn't addressed—a leak, condensation, or poor ventilation—the mold will come back.
It is always recommended to address moisture issues before or at the same time as cleaning the ducts.
How can you avoid low-price scams?
Be wary of offers for 99$ to «clean everything.» It’s almost always a bait-and-switch tactic.
Once they arrive on site, these companies will find «urgent problems» and present you with a final bill ranging from 800$ to 1,500$.
Always ask for a detailed written estimate after an inspection. Check for certifications (INVC, NADCA, RBQ). Read online reviews.
If a company refuses to show you its certifications or give you a written quote before getting started, walk away.
Is the cleaning process noisy for the tenants?
Yes, it's noisy. The industrial vacuum cleaner and the rotating brushes make noise.
It's usually no worse than a powerful household vacuum cleaner, but it can take several hours, depending on the size of the system.
We recommend notifying your tenants in advance and scheduling the work during the day when most people are at work. You can also coordinate to work on one unit at a time if necessary.
Is this mandatory in Quebec?
Not with a mandated frequency, as is the case with smoke detectors.
However, your obligation to provide safe and sanitary housing may require you to clean if a tenant proves that the air quality is harmful to their health.
Legally speaking, this is a gray area, but more and more property management companies are recognizing air quality as a health and safety issue. It’s better to be proactive than to have to react after a complaint is filed.
How long does the entire procedure take?
For a typical duplex, allow 3 to 5 hours. For a triplex, allow between 5 and 7 hours, depending on the complexity of the system.
The work can be spread out over two days if that's more convenient for your tenants. The important thing is to do the work properly without rushing.
Can your tenants stay in their apartments while they're being cleaned?
Yes, but it's noisy, and you have to access the vents in every room.
If possible, it’s more convenient for everyone if the tenants aren’t home during the work. But it’s not required—we can work around their presence if necessary.
Conclusion — Strategic Maintenance for Healthier Housing
Owning a duplex or triplex in Montreal is an investment that requires smart maintenance.
Your tenants spend 90% of their time indoors during the winter. The quality of the air they breathe directly affects their health, comfort, and satisfaction.
Clean ducts reduce complaints, improve tenant retention, and protect your investment in the long term.
It's not an expense—it's protection.
At Vortex Air, we’ve been helping Montreal landlords maintain healthy multi-unit buildings for over 10 years. We understand the specific challenges of plexes because we work on them every week.
If you're wondering whether your ducts need attention, we can give you a clear answer after a free inspection.
Plan Your Duct Maintenance More Effectively to Protect Your Tenants Start by finding out exactly what condition they're in.
Contact us at 514-214-7492—we're available 24/7—or visit vortexair.ca.
Because a well-maintained building starts with the air we breathe there.
