DIY guideDucts and vents
Walk the ductwork and seal loose joints
Follow the ducts you can see, find the leaky, crushed or sweating ones, and seal loose joints with foil tape or mastic.
- 30 min to 1½ hr
- 8 steps
- Every step animated
8 steps
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With a flashlight, follow each duct from the furnace across the basement ceiling and into any space you can see.
With the fan running, hold the back of your hand by each joint. Air puffing out is a leak.
Note joints pulled apart, flexible runs crushed or kinked, and ducts hanging loose.
Drips or rust on a duct in summer mean cold air in a damp space. Note where.
Set the thermostat to Off before you work on a duct.
Wipe dust and grease off a hand's width each side of the joint.
Duct edges are sharp: wear gloves.Wrap foil tape round the joint, pressing it flat, or brush mastic over it. Never cloth duct tape: it dries out and falls off.
A run come apart, a crushed one, or a leak inside a wall or ceiling: ask Handyman for a heating and cooling tech.
What you need
- A flashlight
- Foil tape or duct mastic and a cheap brush
- Gloves
- A rag
Call a pro if
- A run has come apart or is crushed
- The leaky joints are inside walls or ceilings
- Ducts sweat or drip every summer
- Rooms stay too hot or cold after sealing
Handyman says: Come apart? I'll find an HVAC tech.
Free for every home. Handyman asks a few questions, then books a pro it trusts.
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