Why Does Sheet Metal Make Noise

A sudden wind gust knocked me down and the plywood sheet went sailing out of my hands.

Why does sheet metal make noise.

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. However if you take a sheet of metal which isn t tightly stretched and wham it it starts to wobble freely. If every time you turn on the heating or cooling system the air ducts start popping and banging read the rest of this article for tips on how to reduce and even stop the noise entirely. Following are common duct noises and what may be causing the problem.

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. 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. 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.

Metal ducts have gauge ratings which reflects how strong the metal is. When following these tips some say their metal roof is even quieter than their old shingle roof. A thick and strong metal can withstand more pressure therefore making it less likely to expand which reduces the popping noises. Rattling noises are often the result of loose metal ducts knocking against each other.

As ducts age the sealing fails and duct connections wiggle loose from the static pressure. 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. That wobbling causes the sound waves to move differently in the sheet giving the wobbly wub wub sound. Duct sheet metal may cause all sorts of noises from one or several different reasons.

This is a step that must be taken during the installation process. To relieve this stress the sheet metal buckles slightly outward making a booming or banging sound. The lower the gauge rating the thicker and stronger the metal.