Duct Supports – The proper type of Duct Support

Date Added: March 26, 2011

Author: eric.hassfurther

HVAC ducts run across the tops of most roofs, and these ducts carry air to separate parts of the building. These ducts will often run across the top of the roof, but at times they may run below the roof also. Because these ducts are made of metal, because they can vibrate when attached to a air handling unit, and because they run above the roof’s surface, they need to be supported up off of the roof so that the sharp metal does not damage the roof’s membrane. So, how do you prevent this from happening and, what do proper rooftop duct supports look like?

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Often times, a rooftop duct support is made of a combination of sheet metal, and uni-strut. This is a consistent element. The two things that often vary are the shape of the duct support and how it interacts with the roof’s surface. I.E. does it attach, penetrate, or just sit on top. Let’s explore these a little further:

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  1. The proper duct support design: Often times you will find a duct support that was fabricated by the HVAC contractor. These duct supports frequently support only the bottom side of the duct. This is not sufficient because high winds can then blow the ducts horizontally. The proper duct support should be and “H-shape”, or a field goal post shape, so that the bottom of the duct rests on the crossbar while the sides of the duct are contained by the top part of the vertical legs thus preventing horizontal motion.

  2. How these supports attached to the roof: Most improper rooftop duct support have vertical legs that penetrate the roof’s surface and attach to the structural metal of bottom side of the roof. While this does make them sturdy, this roof penetration often creates roof leaks and ruins the waterproofing integrity of the. The proper way to support the duct is by using a non-penetrating rooftop duct support. These supports have large base plates that sit on top of the roof’s surface for the vertical legs of the duct support to attach to. The base plates do not penetrate the roof’s surface, but instead sit on top while still providing a very sturdy base for the duct support. By using this type of duct support base, the roof is free from the concern of leaks because of the penetration, and your ducts supports are as still very sturdy

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To see an example of a proper rooftop duct support, be sure to visit www.RoofStuffinc.com.

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Eric is the President and Founder of Dallas based RoofStuff, Inc (www.RoofStuffinc.com) a manufacturer of pipe supports, duct support, and other rooftop accessories. RoofStuff, Inc was founded in 2002.