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How to Support Ducts On A Rooftop

So you made the decision to run your ductwork on the rooftop, now what?

Field Fabricated Supports

In many cases, non-engineered fabricated supports are built based on immediate need instead of long term performance. When supports are built on site, there can be factors that are overlooked. It is not uncommon for the weight distribution to be overlooked or improperly calculated. Improper support design can cause damage to the roof membrane, roof structure and interior assets. These are a few of the reasons as to why you should consider an engineered support and why it will give you your best chance at a long and damage free roof.  

Some Factors To Consider:

1. Adjustability On Width And Height– Can your duct support be modified quickly to reduce labor time?

2. Spacing– Are you supporting round ducts or rectangular ducts? Typically this will factor into the amount of supports needed and the distance between them.

3. Bases– What type of base will your duct support have? Should you use penetrating or non-penetrating support bases?


The material that the bases are made of will need to be able to withstand the climate. Weather, heat, cold, rainfall and potentially corrosive environments all can be a factor. You will want to ensure whatever support you use will withstand the necessary length of time. Wood, plastic and rubber are all options for the base of the supports. However, wood deteriorates which is why it’s being used less and less. It is too risky to have it deteriorating and pressing into the roof membrane. 

Plastic can also have some limitations when it comes to climate. Sitting in direct sunlight, throughout cold winters takes a toll on the material. You will likely want your duct supports to last the length of the roof. 20-30 years is a long time for a piece of plastic to not break down.

DS & DSW Series

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The DS & DSW series is designed to provide support for ductwork. The crossbeam has the ability to be moved up or down on the vertical supports to accommodate varying heights.The bases feature an 8-hole wing fitting for added stability. Our patented C-Port wide-body bases are used with the DSW series.

The DS & DSW series are perfect for situations where the ductwork widths are consistent but the height may vary (as it often does). 

DSA & DSAW Series

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The DSA & DSAW Series are also designed to support ductwork. The differentiating feature with this series compared to the DS & DSW is that it features a telescopic crossbeam which allows for 

maximum adjustability. The telescopic crossbeam (which comes in 3 different sizes) can be quickly adjusted on site for a perfect fit.

The DSA & DSAW Series do not come with the upright strut. Since heights are very often changing on a rooftop, we supply all the hardware and fittings to attach the bases to the uprights as well as the crossbeam. The telescopic crossbeam accommodates any 1 5/8″ x 1 5/8″ strut which is readily available to most contractors. The strut can be cut to any height and installed in about a minute. 

One last feature to point out is the swivel fitting that connects the uprights to the bases. It allows the contractor to support ductwork on a sloped and low pitch roof. Equipped with a bolt through the strut, you can secure the angle with a quick tightening of the nut. 

The DSA/DSAW is great for all the other applications that the DS/DSW Series might miss. It provides maximum adjustability on width (and height). When you work with Clearline Technologies, you will get the best support – both in terms of product and service. All of our product lines can be customized, and extra bases can be added for extra stability and a higher load rating. We can also add other features like Slipsheets & extra crossbeams for multiple ducts and lines. Contact us for a free quote at 1-866-444-0009 or sales@clearline.ca.

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