'Attic rain' could plague more Alberta homes this winter

This winter's frigid weather in Alberta could trigger more cases than last year of "attic rain"— when warm, moist air sneaks into the attic, freezes, then melts in warm spells like chinooks.

Newer and more energy-efficient homes can be more likely to have ice build-up in attics

'Attic rain' occurs when warm, moist air sneaks into the attic, freezes during cold weather and then melts during warm spells like chinooks, leaking water into the home. In extreme cases, like this attic, it can be as thick as six to eight inches. (Darrell Paul/Qualistat)

Water stains on the ceiling tipped off homeowner Wes Lysack that something was wrong. 

"There was roughly seven spots per room that were the size of about a baseball in the middle of the room," said Lysack.

Turned out the water was coming from ice melting in the attic.

It's a problem known as "attic rain." Warm, moist air sneaks into the attic, freezes during cold weather and then melts during warm spells like chinooks, leaking water into the home.

Home inspector Jeff Howells says recent frigid weather in Alberta could trigger more cases of ice rain than last winter. (Dave Gilson/CBC)

Calgary home inspector Jeff Howells says recent frigid weather in Alberta could trigger more cases of attic rain than last winter.

"The longer it stays cold outside, the more frost is going to accumulate," he said.

Attic rain can be more likely to affect newer homes

Attic rain can be more common in newer, more energy-efficient homes that do a better job containing warm air and moisture, said Howells.

All it takes is a few holes around fixtures such as bathroom vents and lights that have not been adequately moisture-sealed to send warm air into the attic.

"We've seen it as thick as six to eight inches of frost," he said.

Darrell Paul, with Qualistat Building Performance Consultants, says the problem could be more noticeable this winter.

With warmer weather on the way, homeowners have to be wary of "attic rain." 0:47

"If you've got a long period of time when you've got that cold and all of a sudden it warms up very quickly, people can have water dripping into their ceiling," he said.

"We've had, especially this year with all the cold weather we've had — extended cold weather — we've had a significant number of phone calls."

Paul says he hopes that new building code regulations will help address some of the design and airflow issues that contribute to attic rain.

Homeowners urged to inspect attics

Meanwhile, Lysack is still assessing the damage and whether repairs can be covered by insurance or his home warranty, but he has advice for other homeowners.

"I think you should go up in your attic to look around, especially when it's cold and see if you have problems like that."

Howells says homeowners can also look for signs like water streaks on the exterior walls of the home.

The dark blue spots in this thermal image show water pooling on the ceiling of a Calgary home. (Jeff Howells/Nu Level Inspections)

With files from Dave Gilson