# Ontario HVAC Ductwork: When to Clean, How to Seal & Why Duct Insulation Matters

**URL:** <https://home.renovation.reviews/t/ontario-hvac-ductwork-when-to-clean-how-to-seal-why-duct-insulation-matters/46893>\
**Category:** Ontario\
**Created:** [April 26, 2026, 6:53pm UTC](https://home.renovation.reviews/t/ontario-hvac-ductwork-when-to-clean-how-to-seal-why-duct-insulation-matters/46893 "2026-04-26T18:53:45Z")\
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**Post date:** [April 26, 2026, 6:53pm UTC](https://home.renovation.reviews/t/ontario-hvac-ductwork-when-to-clean-how-to-seal-why-duct-insulation-matters/46893/1 "2026-04-26T18:53:45Z")

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Ductwork is the circulatory system of an Ontario home’s HVAC. Leaky, dirty, or uninsulated ducts waste energy and reduce comfort. Here is a complete 2026 guide.

**When Duct Cleaning Is Warranted**  
NADCA supports cleaning when: visible mould inside ducts or on HVAC components, vermin infestation, ducts clogged with debris after major construction, or new construction before occupancy. Routine annual cleaning is not supported by research for normal systems. Risk of damaging duct liner from aggressive cleaning is real.

**Professional Duct Cleaning**  
Negative air machine creates suction. Registers sealed. Branch ducts brushed and vacuumed. Blower compartment cleaned. Cost: $400-$800. Avoid $99 specials — bait-and-switch is endemic in this industry.

**Duct Sealing: The High-Return Priority**  
Ontario homes lose 20-30% of conditioned air through duct leaks. Aeroseal (pressurised polymer sealing from inside): $1,500-$3,500. Manual mastic on accessible joints: $500-$1,500. Consistent, measurable energy savings. Pays back faster than most insulation upgrades in leaky duct systems.

**Duct Insulation**  
Ducts in unconditioned spaces (attic, crawlspace, garage) must be insulated. Ontario Building Code minimum R-6. Uninsulated attic ducts lose enormous energy in both heating and cooling seasons.

Find Ontario HVAC contractors and discuss ductwork at home.renovation.reviews.