The sound of cold: House pops, creaks blamed on dry air

McClatchy-Tribune Information Services

AKRON, Ohio ó Chances are things in your house have been going pop in the night.

Or creak. Or groan.

Whatís going on?

Nothing sinister, assures Elwin Robison, a professor in Kent State Universityís College of Architecture and Environmental Design.

When the temperature plummets outside, so does the relative humidity in our homes as we crank up the heat. That dryness causes the wood parts of a homeís structure to shrink and scrape against one another, especially if those parts are under pressure ó say, from the weight of snow on the roof, Robison said.

Sometimes the movement is sudden, causing a popping sound. Sometimes itís slower, causing those creepy creaks and groans.

Robison said the culprit is often rafters moving against the top plate in the attic, with the plywood sheathing on the roof serving as a sounding board to project the noise. But other wood can be to blame, he said, even an outdoor deck thatís subject to force from the weight of furniture or a heavy barbecue grill.

The problem is often more noticeable in older homes, said Joseph Ferut Jr., a colleague of Robisonís in the architecture college. Newer homes are more thermally isolated from the outdoors, he said, and improvements in building science reduce the sudden movements.

While they might wake you, Robison said, strange noises shouldnít cause you to lose sleep worrying about whatís happening to your house.

"Houses are just always moving," he said. When these extreme contractions happen, "they withstand it just fine."