Renovation & Design

MIKE HOLMES: Duct cleaning a good thing -- if it's needed

Postmedia/There are many reasons to have your ducts cleaned.

Healthier air quality, better airflow, more energy efficiency -- yes, I am a fan of duct cleaning. But there's a time and a place for duct cleaning. And it's not always worth the money you pay.

There are a lot of good reasons to have your ducts cleaned. For one, you might notice mould inside the ducts or somewhere else in the HVAC system. (One of the best ways to check for this is to give the ducts a good sniff. Seriously. If there's mould in your ducts, you'll smell it right away.) If that's the case, duct cleaning is the bare minimum I'd recommend. If the problem is bad enough, you'll want to think about cutting away the contaminated duct area and replacing it.

Of course, you'll want to clean your ducts if you think there are vermin, such as mice or insects, living in them, or if you have poor airflow to one or more rooms in the house, that may be caused by a blockage in the ducts. In these cases, keep an eye out either for particles spewing out of the ducts, or little to no airflow in isolated parts of the home.

You might also want to think about cleaning your ducts if you just moved into a newly built home, or just had a major renovation done. If the construction crew wasn't careful, they may have swept all kinds of dirt -- insulation fibres, pieces of drywall, even lunch bags and coffee cups -- into the ducts. Last I checked, this junk doesn't belong in a modern HVAC system.

Some contractors will tell you duct cleaning will take care of your home's dust problem. That's fiction. Dust is everywhere. You create it when you walk, when you open a door or a window, when you cook, and even when you clean. And when you do any of these things, you expose yourself to more dust than you ever would if you stuck your head over a dirty duct and inhaled deeply. So dust isn't a bad thing (if it were, we'd all have breathing problems) and it's impossible to avoid.

Properly done by trained professionals, duct cleaning will remove all the dirt and debris from your ducts. When the job is done, you'll see all kinds of wild things in your ducts you never imagined were there: paper clips, kids' toys and pet food.

But here's the thing: For duct cleaning to be of any benefit, it has to be properly done. That means that the duct cleaner needs to clean all the HVAC system components: the grilles, diffusers, heating and cooling coils, condensate drain pans, fan and motor housing and the air-handling unit. He should also take a close look at the cold-air return. When it's ducted, it's a landing spot for dust and debris, just the same as the hot-air vents. (And when they're not ducted, they're magnets for drawing things like mould spores and insulation fibres into the air supply.) A thorough cleaner looks inside the cold-air return and plenum, as well as the hot-air ducts.

Finally, the good duct cleaner -- the one you took the time to research before you hired -- takes the time to inspect his work after completion. That means he either sends a camera down the ducting, or he cuts away a few small sections of the ducting to perform a thorough visual inspection.

At the end of the job, the cleaner might want to spray some anti-microbial chemical into the ducts, just to kill off any remaining mould. If he offers, refuse. If he's done a good enough job, there's no reason he should spray that stuff. Besides, does it really make sense to spray a pollutant into your home's HVAC system when you've just paid a few hundred dollars to have the air cleaned?

Here's my advice on duct cleaning: If you have a good reason to get it done -- mould, vermin and blockages, or a recent renovation, for example -- do it. If it's been a few years since it was last done, do it. But if you feel you need to do it regularly because you've heard about health benefits, don't. And always, always make sure the cleaner you hire is professional and thorough.


Catch Mike in his new series, Holmes Inspection, airing Thursdays at 8 ET/PT on HGTV. For more information, visit For more information on home renovations, visit


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