Attic rain has been a major issue for many Calgary homeowners this winter. Our team at IDEAL has been called to
dozens of homes dealing with water stains, damaged drywall, and in the worst cases, water dripping directly into
living spaces. This usually shows up after long stretches of cold weather followed by a sudden warm spell, which
Calgary sees often.

Most attic rain problems come down to three things: warm air leaking into the attic, insufficient insulation that
allows heat to escape, and ventilation systems that are not working the way they should. This winter, one problem
stood out more than anything else. Bathroom fan and dryer vent exhaust pipes were not fully connected to the roof
vent, which allowed warm, moist air to spill into the attic instead of out of the home.

Why this happens

Most homes use a standard aluminum roof vent called a gooseneck. It has a curved design with a flapper or grate to
manage airflow and keep pests out. The problem is that the typical gooseneck does not include an internal collar
or pipe for the exhaust hose to clamp onto. Instead, builders and renovators often push the bathroom fan or dryer
hose up to the vent opening and secure it with a small piece of metal or chloroplast. This leaves a gap around the
connection.

When warm, moist air escapes through that gap, it condenses on the cold plywood roof deck. Over long cold spells,
frost begins to form and can grow quite thick. As frost builds, it pushes the hose even farther away from the vent
opening, letting more moisture spill into the attic. Once temperatures rise during a chinook, all that frost melts
at once. The result is attic rain that soaks insulation, leaks through the vapor barrier, stains ceilings, and
causes costly repairs.

How to fix it

The best solution is to replace the standard gooseneck vent with a vent that has a dedicated collar inside. IDEAL
often installs the Primex roof vent because it allows the exhaust hose to be fully connected and sealed. This
keeps warm, moist air moving outdoors where it belongs instead of into your attic. A proper connection greatly
reduces the chance of frost buildup, attic rain, and moisture damage.

If you look at the typical installation, you can see a space between the hose and the metal flange that holds it
near the vent. Ice forms in that space during cold weather and continues to grow. Over time, the gap widens, and
most of the moisture from your bathroom or dryer ends up in the attic. When that frost melts, the water has
nowhere to go but down.

Recommended next steps

If you are seeing frost, moisture, or water stains in your home, it is important to have your attic inspected.
A proper assessment will identify heat loss, ventilation issues, missing insulation, and any failed exhaust
connections.

Our team can review your attic and recommend upgrades such as
attic insulation services,
Calgary attic insulation upgrades,
or insulation removal if existing
material has been damaged by moisture.

To learn more about preventing attic rain and moisture problems, you can also read:

• Attic Rain Inspection and Prevention in Calgary
  
• Prevent Attic Rain and Bathroom Fan Leaks This Winter
  
• Managing Moisture Sources in Attics
  
• Why Attic Ventilation Is Crucial for Homes in Edmonton
  

If you suspect attic rain or moisture problems in your home, book an attic inspection with our team in:

• Calgary and area
• Edmonton and area

Note:  You can see in this photo that there is a space between the metal flange used to hold the bath fan hose up against the bottom opening of the Gooseneck roof vent.  If ice begins to form in this gap it will quickly grow over times of prolonged cold and push the gap even wider.  Eventually a large portion of the bathroom or dryer warm/moist air that the homeowner is attempting to vent will instead be spilling into the attic and causing frost to grow on the plywood roof deck.  When this frost melts Attic rain & damage ensues.