Ducts

Why You Should Have Your Ventilation Ducts Cleaned — and How Often

It's a question we get asked almost every day: is duct cleaning really necessary, or is it a luxury? Here's an honest answer, based on what we actually see in the field in Montreal, Laval and the South Shore.

What Actually Builds Up in Your Ducts

Your ventilation ducts move air hundreds of times a day. And that air is never perfectly clean — it carries dust, pet hair, pollen, textile fibers, cooking particles, and sometimes moisture. Over time, some of all that settles on the duct walls.

In a typical home we open up for the first time after 10 years, we often find a 2 to 4 millimeter layer of compacted grime — and sometimes much more near the furnace plenum.

Why It Matters for Your Health

That buildup doesn't just sit there quietly. Every time your furnace or air conditioner kicks on, a fraction of those particles gets blown directly into the rooms where you sleep, eat and breathe. For a healthy person, the effect is subtle. For an asthmatic child, someone with allergies, or an older adult with respiratory issues, the difference between clean ducts and dirty ones can be significant.

How Often Should You Clean Them?

There's no one-size-fits-all rule, but here's what we recommend in practice:

• Standard home, no pets, no allergies: every 5 to 7 years
• Household with pets or allergies: every 3 to 4 years
• After major renovations (drywall, sanding, demolition): as soon as the work is done
• Buying a home with an unknown maintenance history: right after moving in
• New respiratory symptoms showing up at home: worth taking seriously

The Telltale Signs

• Dust comes back quickly on furniture, even right after a thorough cleaning
• Your vents (grilles) are blackened around the edges
• A stale smell when the furnace kicks in
• Allergies that get worse indoors
• No record of a previous cleaning

What a Proper Cleaning Should Include

Be wary of "ducts cleaned at rock-bottom prices" offers. A proper cleaning includes:

• Negative pressure setup with professional equipment (not just a vacuum)
• Mechanical brushing of every branch — not just the visible vents
• Cleaning of the furnace plenum, fan, and heat exchanger
• Cleaning of the return air ducts, just as important as the supply side
• Before/after photos so you know exactly what you're paying for

The Bottom Line

Duct cleaning isn't a luxury, but it's not something you need to do every year either. The right frequency depends on your lifestyle, your family's health, and the current state of your system. When it's time, choose a company that shows you the work, photos included.