Hearing loud popping or cracking from your walls? Experts say truss uplift is to blame

With fluctuating warm then cold temperatures, homeowners around the city have been hearing loud banging and cracking from their walls and attics.

While the sound may not bring your house down, the owner of First General Property Restoration, specializing in framing and home rebuilds, says the sound is usually the result of truss uplift.

"The reason you're hearing those noises and it's kinda catching people off guard in this cold weather is because moisture migrates into your attic," Moe Barzagar told CTV News Edmonton. 

According to Barzagar, attics function best when their temperature is as close to the outdoor temperature as possible. Roof ventilation is designed to enable this. When an attic is not well vented, Barzagar said it can result in moisture accumulation, which can cause a number of problems, including truss lift. 

Modern homes have attics with insulation and ventilation held together by roof trusses, instead of ceiling joints or rafters. What holds the trusses is a series of boards called chords. During cold snaps, the bottom chord, which is covered by insulation, remains warm. Chords at the top of a truss are above moisture, which can make them expand.

The combination of events can cause the roof truss to bend and flex, and to disconnect from the interior walls below. 

Barzagar said incorrect bathroom venting or even renovations or modifications that cut through vapour barriers to install potlights can create openings for moisture to move into an attic.

The good news is that truss uplift doesn't usually cause major problems, Barzagar said.

More severe cases of truss uplift can put cracks in the paint in walls or drywall. Barzagar recommends checking the edges of an attic for insulation stops, or pieces of cardboard that protect a soffit from getting covered and ensuring airflow.

Richard Amiotte, who has heard the banging for the past few days, says he sympathizes for his more than 50-year-old home.

"(I'm) getting old," Amiotte said, adding his own bones get a little creakier each winter. "I can see how she feels."