Weathering the Storm with Rooftop Supports

Weathering the Storm with Rooftop Supports

Green Link, Inc. 

Presented by Kaitlyn Briggs

(Kaitlyn Briggs) This presentation was originally featured as part of AEC Daily’s Virtual Education SpotLight Symposium in December 2023. We received several questions over the course of the day, but unfortunately didn’t have time to answer them as part of our presentation. We were excited by the engagement we received from the attendees, so we’ve included a brief Q&A at the end of the video.

Alright, with that out of the way, I’m going to go ahead and get started!

Our company was founded in 2016 to discover innovative solutions for sustainable construction. We believe that sustainability and efficiency go hand in hand, which means that we keep our eye on the ever-evolving landscape of energy-efficient technology and the challenges that these unique technologies face. 

One challenge that we all find ourselves facing lately, both personally and professionally, are the energy costs that have surged 25% over the last decade. This graph here, from the U.S. Bureau of Labor Statistics, shows a steady increase over the last ten years, with a significant jump between December 2021 and August 2022. Current averages hover around 17 cents per kilowatt hour, and that number is forecasted to continue to rise over the coming years. 

The U.S. Energy Information Administration predicts that energy prices will rise a further 2% in 2024 alone. 

Energy-efficient equipment can reduce these costs by up to 30%.

One of the first steps in enhancing energy efficiency is to replace old HVAC units with newer, energy-efficient equipment. Much like an old car loses its fuel efficiency, older HVAC units become less efficient over time. Typically, HVAC equipment has a lifespan of 10 to 15 years. Beyond this period, their efficiency declines, leading to higher energy consumption and, in turn, increased energy costs.

Higher energy consumption also leads to more CO2 emissions. Currently, about 30% of Greenhouse gasses are produced in the residential and commercial sector, so it’s not surprising that the National Building Performance Standard Coalition has committed to reducing emissions and moving towards sustainable building performance standards – which means one-quarter of all commercial, Federal, and multifamily buildings in the US are in the process of converting to more energy-efficient equipment.

In fact, earlier this year the Department of Energy committed 250 million dollars to the acceleration of heat pump manufacturing in the United States. The goal is to create cleaner energy options in the US and reduce energy costs and consumption across the country.

I’m sure you’re wondering, “what does this have to do with rooftop supports?” In short, what the energy-efficiency and sustainability movements boil down to, is that three to six million new HVAC units are being installed every year often for the previously stated reasons, and all of these new units have to be placed and supported properly to extend the life of the equipment and protect the buildings they’re servicing.

In the past, units had to be installed on the ground due to size and weight restrictions. However, in recent years, these units have been streamlined, with smaller, lighter units producing just as much, if not more, output than larger units used to. Architects and engineers are taking this as an opportunity to move units from the ground to the roof, reducing the overall footprint of the building, reducing noise pollution, and making units easier to access for maintenance.

Since 2020, over 1.2 million apartments have been built, with another million projected to be completed by the end of 2025. But this trend extends beyond apartments; we see large-scale construction projects, such as multi-purpose office buildings, schools, hospitals, and government buildings, all requiring new HVAC systems.

The number of units being installed each year is only going to continue to increase as apartment buildings and office buildings continue to replace single-family homes and single-purpose buildings.

Traditionally, installation included wooden four-by-fours that would rot and deform over time. Without adequate support, the system may start to sag, misalign, point load, or suffer a total system failure, leading to costly repairs, hazards, and an inability to continue normal operations.

These pictures are from projects we have replaced existing supports on, installations that we have seen over the years, and installations that have been sent to us from all over the country. As I’m sure you can agree, there has to be a better way to support expensive equipment like this than rotting wood and leaning blocks.

Beyond the visuals here that illustrate what can go wrong with improperly supported equipment, there are more immediate concerns that recommend a robust support system.

Proper support and maintenance of rooftop equipment are incredibly important when it comes to optimal performance and mitigating potential risks. 

Roof-mounted HVAC equipment is more prone to environmental factors than ground-mounted HVAC equipment, which often has natural protection from wind and snow build-up that is not typically available on rooftops, where units are generally freestanding instead of against walls or under shelter. The support frames for ground-mounted equipment, an example of which is pictured here, are lightweight and, while not flimsy, are designed to support lighter units without an option for mechanical attachment and, as such, are not suited to heavier equipment. 

In general, the environmental factors that cause the most trouble for roof-mounted equipment are wind and snow build-up. 

Wind velocity and pressure forces vary greatly at rooftop elevations from those on the ground. As you can see in this graph, wind pressures at ground level are a quarter of the pressures that are present on a ten-story building. The difference in velocity and pressure correlates directly with the uplift and tip-over of the equipment. As height increases, it becomes more and more important to make sure that the equipment is properly secured and supported.

A properly sized steel frame support will give the equipment a wider base that resists tipping. For example, a mini-split has more height than depth, creating a relatively small footprint for its size, making it prone to tipping in high wind situations. 

Securing the mini-split to a, for example, three-by-three frame would increase the footprint of the unit, decreasing the risk of tipping even before attachment is taken into consideration. 

As for snow build-up, the primary concern is that wind gusts or very heavy snowfall will cause banks of snow to build up on the sides of the unit. Build-up of snow around a unit can restrict airflow and send a heat pump into overdrive, leading to increased energy costs or, in extreme cases, emergency shutdowns or total failure. There is also potential for ice build-up inside the unit, which can cause damage to the condenser coils.

The best way to avoid snow build-up is to remove the opportunity for the snow to gather by elevating the equipment. In areas with particularly high annual snowfall, units should be elevated according to local codes or between 12” and 24”, depending on the size of the unit and the location, if there are no codes in place. Of course, in extreme cases when a snowstorm brings multiple feet of snow at a time, it’s still important to inspect the units and make sure that snow drifts haven’t formed on or around your equipment.

Properly supported equipment will, in addition to mitigating the unavoidable environmental risks, reduce the potential for some of the problems that we previously attributed to rotting, wooden supports. A well-supported system ensures proper alignment and stability, reducing unnecessary vibrations and movement that can lead to wear and tear, and protecting the equipment from damage that can compound over time, leading to lessened efficiency, higher energy costs, and more frequent equipment replacement. Properly supporting equipment may even prolong the life of the unit by reducing instances of mechanical wear and tear from misalignment or slippage. 

A properly supported unit will also protect the roof from potential damage. The footprint of the base allows for proper weight distribution, eliminating point loading on the rooftop and protecting the integrity of the underlayment. Elevated supports allow water to flow across the roof as designed instead of pooling around the equipment and leaving standing water that will eventually cause leaks that could be costly to repair. A proper base will also allow for a reduction of equipment vibration. Vibration could cause abrasion that could damage the roof membrane.

High-quality materials and adaptability are the key to creating a support that will protect your equipment. Whether you’re looking to support a single unit or many, it’s important that your frames are designed to suit the equipment, instead of being placed on a “one-size-fits-all” frame that may cause more damage than it prevents. 

Green Link designs custom solutions for single- and multi-unit supports that are adjustable on-site to account for imperfections in the roof that may result in non-level surfaces. Designed and built in-house, Green Link is committed to making sure that our products meet your expectations in every way. 

We offer a variety of options that will suit any project. 

Attachment to the roof is often a concern for many contractors. Penetrating the roof is frequently a last resort, as every roof penetration is a potential leak. Oftentimes, the alternative is to avoid proper attachment altogether. 

While this may be a viable option in some low-wind locations, especially with heavier units, loose-laying equipment is not always the best choice. While a slip sheet, like the ones pictured here, may be enough, the best option may be an adhesive, like Green Link’s Adhesive/Sealant. 

Green Link Adhesive/Sealant is a polyether-based, moisture-cure formula that has been used in the construction industry for many years and has earned a reputation for high performance, adhering to a wide range of roofing membranes and yielding a strong, long-lasting bond. As an adhesive, it provides up to 275 psi bond strength between the 7” Universal Base and single-ply or built-up membranes. As a sealant, it is a viable option for a waterproof seal when mechanical attachment is necessary.

While pre-galvanized strut is the standard across the industry and at Green Link, there are some projects that call for different materials. Green Link’s StrutFrames can be built from a variety of materials, including hot-dipped galvanized strut in corrosive environsments, aluminum when lightweight frames are critical, and stainless steel when rusting is the prevalent concern.  

Green Link also offers several options for pipe and duct supports that are built to the same standards of efficiency and sustainability. 

The surge in energy costs and the push for sustainability underscore the critical need for energy-efficient systems that are ssupported – both literally and figuratively – by well-designed rooftop support systems. Traditional installations are falling short across the board and optimized solutions like Green Link’s StrutFrames are the future of rooftop installations.

The best time to pivot towards a greener and more sustainable future was many years ago. The second best time is today. Green Link invites you to weather the storm with us as we move towards a sustainable and efficient future for the HVAC and construction communities.

If you’re interested in learning more about Green Link products, feel free to reach out to us. We’ll be happy to answer any questions you have or discuss any projects you’re working on. I’ve also included our contact information in the description for easy copy/pasting.

Alright, we’re going to move right into the Q&A section. These questions were submitted during the AEC’s Virtual Education SpotLight Symposium, so if you asked something during our original presentation, make sure to stick around for this. Joining me is Angela Peck, from our technical department. Angela, do you want to go ahead and introduce yourself before we get started?

Alright, we’re going to move right into the Q&A section. These questions were submitted during the AEC’s Virtual Education SpotLight Symposium, so if you asked something during our original presentation, make sure to stick around for this. Joining me is Angela Peck, from our technical department. Angela, do you want to go ahead and introduce yourself before we get started?

(Angela Peck) Hi, I’m Angela Peck, I’ve been with Green Link since 2018.  My main focus here is in takeoff and estimation for custom projects.

(Kaitlyn) All right, our first question is: in your presentation, you mentioned the importance of roof supports due to wind loads. How does your company factor wind loads into design?

(Angela) When looking at wind, we consult the ASCE 7 Hazard Tool, and obtain data specific to the building location, roof height and risk factor.  We then input this information into the ASCE 7-16 equations, this allows us to determine whether the equipment would be stable free-standing, or if it requires additional attachment.

(Kaitlyn) Okay, our next question is: are your products able to be attached to the roof with only adhesive?

(Angela) In some circumstances, yes.  If the roofing membrane is fully adhered with a minimum peel strength 13 pli (lbs per linear inch), and wind forces do not exceed the physical properties of the adhesive used to bond the base to the membrane.  When these conditions are not met or when the membrane is not fully adhered, mechanical fastening and adhesive are necessary to avoid damaging the building envelope.  In high-wind scenarios, we recommend anchoring with additional products for a greater safety factor.

(Kaitlyn) Okay, our next question reads: what roof slope can your products accommodate?

(Angela) Green Link products are designed to be used with flat and low-slope roofs.  At pitches higher than a ½:12  (or about a 3°slope) we can provide additional blocking to accommodate the slope for up to a 2:12 pitch.

(Kaitlyn) If I wanted to specify your products, where would I find BIM resources? 

(Angela) Shop drawing and .dwg files of the KnuckleHeads and MetalHead are available on the technical resources tab of our website. We also host files at and, both of which are free to use but require registration to download objects. For custom projects involving unit frames and larger pipe stands, we can also provide .dwg files directly that reflect the entire build and are not limited to the base.

(Kaitlyn) Okay, our last question reads: weight distribution on the roof is important to me. What are the weight limits of your product?

(Angela) Green Link offers two sizes of base for the KnuckleHead system, the universal base 7” in diameter with 38 sq in of surface space, and the Big Base is 12” in diameter with 113 sq in of surface space. The MetalHead provides 47.5 sq. in surface space. (Our literature on this says over 50? I think this is wrong)  These points of contact with the rooftop allow the weight of the units/pipes supported to be distributed properly to avoid point loading and damage to the roof surface. Compressive strength for foam underlayment varies based on composition and rating, this is one of the reasons we suggest placing no more than 600 lbs per KnuckleHead.

(Kaitlyn) Thank you for that Angela, those were some great answers! If you have any follow-up questions, feel free to leave those in the comments or use the contact information in the description to reach out to our office.