Duct Supports – What does a good rooftop Duct Support look like?

Date Added: March 18, 2011

Author: eric.hassfurther

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On the roofs of most buildings there are HVAC ducts that are running across the top of the roof. These ducts carry air to separate parts of the building. For a number of reasons sometimes these ducts run across the top of the roof instead of below the roof. Because these ducts are made of metal, 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 puncture the roof’s membrane. Let’s explore then the aspects of a proper support: What do proper rooftop duct supports look like?

Majority of the time, a rooftop duct support is made of sheet metal. This is a consistent element. The two things that are not consistent though, are the shape of the duct support and how it attaches to the roof. Let’s explore these a little further:

  1. The design of a duct support: On many roofs you will find a duct support that was fabricated by the HVAC contractor. These duct supports often only support the bottom side of the duct. This is not sufficient because in high winds can blow the ducts laterally. The proper duct support should be and “H-shape” so that the bottom of the duct rests on the crossbar while the sides of the duct are contained by the upper legs of the “H-shape” thus preventing lateral motion.

  2. How these supports attached (or not) to the roof: Most improper rooftop duct supports are made of angle iron and this angle iron penetrates the roof’s surface and is attached to the structural metal of bottom side of the roof. While this makes them sturdy, this penetration in the roof often creates roof leaks and ruins the integrity of the roofing membrane. 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 “H-shape” to attach into. These base plates do not penetrate the roof’s surface but still provide a very sturdy base for the duct support. By using this type of duct support base, your roof is free from the worry of leaks because of the penetration, and your ducts supports are as sturdy as ever.

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

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

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