Why Does Sheet Metal Make Noise

If your roof is installed without a proper roof underlayment you will experience the kind of noise that causes people to think buying a metal roof is a bad idea.

Why does sheet metal make noise.

The noises are usually caused when the thin sheet metal of the ductwork expands to accommodate the sudden change in pressure caused by the airflow. When following these tips some say their metal roof is even quieter than their old shingle roof. Rattling noises are often the result of loose metal ducts knocking against each other. This is a step that must be taken during the installation process.

However if you take a sheet of metal which isn t tightly stretched and wham it it starts to wobble freely. Generally the noises occur after the hvac system comes on and the conditioned air begins rushing through the ductwork on its way to being delivered in your home. A thick and strong metal can withstand more pressure therefore making it less likely to expand which reduces the popping noises. Most home ductwork uses a 24 26 gauge sheet metal which is a sweet spot.

Duct sheet metal may cause all sorts of noises from one or several different reasons. While all hvac systems make some noise when they are on when there is excessive noise such as popping knocking and banging it can indicate a problem. Amplified within the thin sheet metal enclosure of the ductwork this noise usually seems louder than it actually is. Years ago as a young builder i almost got blown off a roof while trying to carry a sheet of 4 by 8 plywood.

The lower the gauge rating the thicker and stronger the metal. Metal ducts have gauge ratings which reflects how strong the metal is. Installing a metal roof over a solid deck with a good underlayment like double bubble and with an insulated attic airspace below makes it easy to control the noise. That wobbling causes the sound waves to move differently in the sheet giving the wobbly wub wub sound.

As ducts age the sealing fails and duct connections wiggle loose from the static pressure. Following are common duct noises and what may be causing the problem. To relieve this stress the sheet metal buckles slightly outward making a booming or banging sound.