Furnace Duct Leak Sealing — Save Energy and Improve Comfort
Published: July 23, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
Signs of Leaky Ducts
Rooms farthest from the furnace are hard to heat or cool, dust accumulates quickly on surfaces (leaky return ducts pull dust from attics/crawlspaces), high energy bills despite good insulation, whistling or whooshing sounds from ductwork, and visible gaps or disconnected joints at accessible duct sections.
DIY Duct Sealing
For accessible ducts (basement, crawlspace): use mastic (a paste-like sealant applied with a brush) on all joints and seams — this is more durable than tape. For small holes and cracks: use foil-backed HVAC tape (not standard duct tape, which fails quickly). Seal supply and return ducts. Wear gloves and a dust mask — old ductwork may contain debris.
Professional Sealing Cost
Professional duct sealing: $500-2,000 depending on the home size and accessibility. Methods: mastic sealing (most durable), aerosol-based sealing (seals leaks from inside the ducts — best for enclosed ducts), or a combination of both. Professional sealing typically saves $200-500/year on energy costs, paying back the investment within 2-5 years.