Leveling and Separating Steel I-Beams on Rooftop Copings

Last week, we looked at a two different low slope or flat roofs with high beams, in different conditions of rust and or proper coatings.  We talked about the issues related to oxidation and deterioration from lack of having a proper coding. Today we’re looking at some of those same rooftops but discussing the issues related to leveling of i-beams on rooftops and the separation between those steel i-beams and the substrate metal coping.

In this case, these steel high beams are heavy structurally capable elements that are basically just set and held down in place by gravity alone. They are not actually connected through a fastener or any means of attachment to the roof itself.  Technically, the building code requires that the I-beam is be set in place and secured by mechanical means, essentially fastened in place but not fasting through the coping itself because fasting through the opening is prohibited although that incorrect method is extremely common in the case of PV solar panel installation.

Some quick code references which seem to address the issue directly, or at least clearly enough, follow below:

2017 District of Columbia Building Code (based on the 2015 International Building Code)

  • Section 1604.8.2 Structural member anchorage: “Anchorage of structural members shall be designed and installed in accordance with the applicable provisions of this chapter and approved by the construction codes official.”

2017 District of Columbia Residential Code (based on the 2015 International Residential Code)

  • Section R317.3 Structural Member Attachment: “Structural members shall be positively anchored or fastened to resist both vertical and lateral forces.”

One of the concerns about not anchoring i-beams in place is related to the potential for shifting or moving in extremely high winds or weather conditions. It’s hard for typical wins to move elements like this because they are extremely heavy, but when attached to a mechanical systems, if the mechanical system were to move in the wind and the attached I-beam may also move as well.  It seems like the concern may also be compounded by the the fact that a small spatial shift, on a slope surface may lead to additional movement, just by restabilization with gravity.


The picture below shows the leveling of the lower side of the I-beam framework by using a set of three plates sandwiched together on top of the aluminum coping.

leveling and separating steel i-beams

The plates are used to level the i-beams from one another as the root is sloping downwards, the parapeting coping also run downwards and to install the mechanical equipment without adjusting that slope to be closer to level might then position the HVAC equipment with too much angular slope as well. So in this case they’ve used these metal plates to raise the lower I-beam. If you look closely though in the next picture below you can see that those metal plates are set directly against the aluminum coping without any impermeable non-conductive material separating one from the other. 

There are requirements throughout the building construction industry based on the principle of separating dissimilar metals to prevent corrosion or deterioration related damage. In the case of a steel I-beam resting on an aluminum coping, it would be advisable to separate the two with a non-conductive material or coating to prevent galvanic corrosion of the aluminum.

separating steel i-beams

This particular HVAC condenser unit was set with a vibration isolation pad between the unit and the IBM itself, but in some cases, we can see and believe that it would be better to also install vibration isolation between the still I beams themselves and the substrate coping as well.

separating steel i-beams framework

In the next picture below, you can see there is nothing separating the steel I-beam from the aluminum coping and it just looks very concerning for a couple reasons, here though in the case of the issue about vibration isolation, some more information follows from the building code.

The 2017 District of Columbia Construction Codes, based on the 2015 International Mechanical Code (IMC), have a specific section dedicated to vibration isolation:

Section 307.3 Vibration isolation for equipment “Vibration control measures shall be provided for machinery, piping, and equipment where recommended by the manufacturer or when necessary to prevent transmission of vibrations that could cause structural damage or become objectionable to occupants of the building.”

This section clearly states that vibration isolation is required when recommended by the equipment manufacturer, or when necessary to prevent structural damage or disturbances to building occupants.

uses of separating steel i-beams

Additionally, Section 307.3.1 goes on to provide more specific requirements:

“Vibration control shall be accomplished through the use of approved vibration isolation materials and equipment mounting provisions, including inertia bases, vibration isolators, and flexible connectors.”

So, according to these code sections it could or should be interpreted that, if the mechanical equipment on the roof is expected to generate significant vibrations that could be transmitted to the building structure and become objectionable to occupants, vibration isolation measures must be implemented. This could involve the use of vibration isolators, flexible connectors, and or inertia bases between the equipment and the supporting I-beams or structure.

The code recognizes the importance of mitigating vibrations, not only for structural integrity but also for the comfort and wellbeing of building occupants. It’s useful (and technically required) for HCAC contractors and building owners to follow these requirements and consult with equipment manufacturers or mechanical engineers to determine the appropriate vibration isolation measures for their specific installation.

uses of leveling and separating steel i-beams

We recommend every building owner in DC who values the longevity of their roof (and their investments) and building use a contractor who values the simple and important principles of proper roof construction like Dupont Roofing DC. Learn more about our company and the proper techniques of working with roofing on historic buildings in Washington DC here on our blog at DupontRoofingDC.com, and you can call us at (202) 840-8698 and email us at dupontroofingdc@gmail.com.

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