When Attic Ducting Starts Leaking

When the ducting in your attic starts leaking, cracking, or whole joints pull away you could have several unfortunate events happening. This is because leaks spew out moist humid air, even droplets of moisture into your roof space. And this can result in mould growth which could in turn damage your ceilings.

Leaky ducting is surprisingly common. That’s because attic ducts are flexible to get around tight corners, and installers can inadvertently strain joints while they position them in place. The only workaround we know is an annual inspection, which involves climbing into the attic, inspecting thoroughly, and making good any defects.

Where Is Attic Ducting Most Likely to Leak?

The short answer is anywhere along the duct run, if the installation is aging. Although with new ones the leaks are most likely to be at joints. In other words where a run of duct pipe connects to an extraction point like the ceiling louver in our first illustration. Or where it exits through a roof, gable or wall.

leaking attic ducting in calgary — A Ceiling Fan Venting Incorrectly to a Soffit (Image Energy Smart Academy BY Public Domain)

Here are common failure points we encounter in attics when we inspect:

1… An entry to an extraction duct pulls away from – or was never properly attached to – a vent fan protruding through the ceiling.

2… An exit from an extraction duct pulls away from – or was never properly attached to – a collared point in a wall or roof junction.

3… A duct does not terminate correctly at an exit collar. Instead it points loosely to a grill set in a soffit or wall.

4… A duct from a furnace – which may vent a fair amount of moisture leaks into the roof space at it passes through to the outside.

How Do I Know If a Duct is Leaking Moist Humid Air

There is no reliable way to detect early moisture in an attic other than climbing through the trapdoor to look. For if you wait until your ceilings show damp, you may have already incurred some damage.

Call Valiant Exteriors if you believe you have a ceiling duct problem, or send us a message here. Our attic inspection rates are surprisingly reasonable and we’ll provide a written report.