Lightning Protection Systems on Occupied Roofs
Special Risks and Unique Design Opportunities
Rooftop decks, terraces, and gardens that will be visited by building occupants are classified in the International Building Codes as “occupied roofs.” Occupied roofs are at high risk of being attachment points of lightning strikes because they are located at the top and/or perimeter of buildings. More information about how to determine the locations on a structure where lightning is most likely to attach, visit our page on the Rolling Sphere model.
Occupied and green roof areas offer designers limitless opportunities to make creative choices for the materials, function and aesthetics of the space. The design of the lightning protection system for these locations is similarly open to ranging creative possibilities. So long as designs adhere to just a few basic criteria, project planners are free to plan their rooftop spaces for maximum enjoyment and utility.
Lightning protection design considerations for occupied rooftops:
Exposed components of a lightning protection system should be compatible with the terrace design, furnishings, and finishes.
Exposed elements of the lightning protection system should be detailed to avoid distracting from views. In the photos below, the lightning rods have either been replaced by the metal railings or integrated so seamlessly that they are undetectable.
People in close contact with lightning protection systems may accidentally or deliberately damage exposed components of the system. Wherever possible, the air terminals, connectors and conductors should be designed and installed to minimize potential damage or displacement.
Attention must be given to locating and detailing lightning protection cables, connections and through-roof penetrations so they will not interfere with the enjoyment of the terrace.
The lightning protection system may have to be coordinated with green roof areas. Rooftop trees, trellises and light poles can be integrated into the lightning protection system.
Special Design and Installation Criteria
To seamlessly integrate the lightning protection with occupied roof designs, metal rooftop elements can be placed where the lightning air terminals would normally be located. These rooftop strike termination devices can be used in lieu of air terminals so long as they are permanent parts of the building and are constructed of metal that is at least 3/16 inch thick (0.064 inch thick for handrails) and is made electrically continuous with the lightning protection system. Railings, light posts, canopies and shade structures, decorative and sculptural items, and other metal fabrications can be used as strike termination devices if properly positioned.
Rooftop lightning protection for occupied roofs must still be part of a total building lightning protection system. All the lightning protection standards that apply to the complete structure must be observed.
For assurance that the lightning protection system is installed in compliance with recognized safety standards, specifications should require inspection and certification of the system by the Lightning Protection Institute – Inspection Program (LPI-IP).
Contact East Coast Lightning Equipment for further information regarding specifying lightning protection systems for occupied roofs. ECLE can also help you locate qualified lightning protection professionals, certified by the Lightning Protection Institute, to assist you with design and installation services.
Additional examples of creative lightning protection system integration can be found on our Sculpture & Custom Decorative page.
Occupied RoofsMuseum of Modern Art Rooftop | New York City, NY 01 / 02
A unique lightning protection system was installed on this special rooftop exhibition at Museum of Modern Art, New York City by Associated Lightning Rod Company. (Photo: Doug and Mike Starn)More About Lightning Protection
Occupied RoofsBuilding Terrace | Boston, MA 02 / 02
The terrace of this building in Boston is in the Zone of Protection created by the higher building elements surrounding it. (Photo: Boston Lightning Rod Company, Inc.)More About Lightning Protection
Does your building require lightning protection?
To Learn More About Lightning Protection for Occupied Roofs Visit
Building Enclosure, Case studies of the lightning protection systems on five highrise buildings with rooftop decks or terraces.
“Standing Ready: Lightning Protection for Hospital Rooftop Gardens, Terraces.”
Medical Construction & Design