Lightning protection systems (LPS) are sophisticated networks that incorporate strike termination devices, lightning current conductors, bonding conductors, grounding electrodes and lightning surge protection devices. While the lightning risk for a structure is often the product of the lightning frequency and the consequence of the strike to the structure, designers typically consider a variety of factors when laying out a system plan. This risk assessment takes into account factors including the building environment, type of construction, structure occupancy and structure contents.
Naturally, a structure’s “landscape” changes over time. Weather events like high winds, ice and snow, and extreme temperatures can degrade a structure’s roof system and affect the continuity of the LPS. Building upgrades can affect the LPS, as well. Roof construction, remodeling, and changes to electrical, mechanical or communication systems can alter or interrupt the lightning protection system. Facility maintenance programs should include an annual visual inspection of the LPS to ensure quality control.
Unfortunately, the importance of integration and maintenance of LPS in conjunction with roof systems is often underestimated. A lack of coordination between roofing systems, LPS specifications and the associated trades can result in a variety of maintenance issues and roofing problems. Construction managers, project designers and building owners can expect the best results when their LPS re-roofing plans include the following:
1) A prescriptive LPS re-roofing specification to outline details for materials, methods and workmanship. LPI provides two industry specifications for LPS re-roofing guidance: a performance specification for bidding and proposal use, and long form specification for construction documents.
2) Reference to the nationally-recognized safety Standards of LPI 175, NFPA 780 and UL 96A as an authoritative source for questions regarding removal, materials and re-installation.
3) Contracting with a certified LPI Master Installer to ensure compliance with nationally-recognized safety Standards. (Note: working with a certified LPI Master Installer to address proper system design is similar to using a RCI certified roofing consultant to assure maintenance of the highest quality protection for the entire roof area of the building envelope.)
4) A third-party close-out inspection (LPI-IP or UL) for LPS quality assurance certification. The LPI-IP provides three types of certifications and inspection options: LPI-IP Master Installation, LPI-IP Reconditioned Master Installation and LPI-IP Limited Scope to accommodate a variety of project needs. UL provides Master Label certification and Letter of Findings services.
Roof Replacement
A major development in the life of any LPS will occur when the building’s roofing system requires major overhaul or replacement. The entire array of direct strike protection for the structure, along with critical bonding elements for internal grounded systems that penetrate the roof, can be affected during this process.
The re-roofing process is seldom as simple as removing and reinstalling the existing lightning protection components. When LPS are inadequately integrated into a roof system and/or not maintained properly, roof-related problems can arise or the LPS may be rendered ineffective. Alterations, rooftop additions or changes from the original mechanical equipment, antennas, security cameras and internal venting will need to be bonded to the lightning protection system as required by the provisions of the safety standards. Other rooftop traffic from window washers, technicians and other contractors can pose a problem for air terminals and cables if careless damage or disconnects from the system occur.
LPS Considerations for Re-roofing
Various elements of the re-roofing process require the supervision of a qualified lightning protection contractor. A decision must be made on the removal and care of existing system components for possible re-installation. The process of removal and re-installation on phased projects needs coordination to maximize time under protection. After the existing components have been removed, the LPS contractor will consider and address re-installation aspects including:
- Identifying and marking to preserve existing and reusable through-roof penetrations.
- Ensuring that structurally mounted hardware is properly anchored according to LPS safety Standards.
- Using construction grade adhesives compatible with the roofing membrane and complying with manufacturer warranties.
- Bonding reinstallation to maintain necessary roof-level potential equalization of the LPS.
- Ensuring circuits of cable conductor are provided with the most direct low-impedance multiple paths to building downleads and structural steel.
- Coordinating LPS on rooftop HVAC units, vents, mechanical equipment, antennae, cameras, skylights and other rooftop appurtenances requiring bonding and strike termination connections.
- Reviewing strike termination devices to accommodate changing needs of building landscape. (In instances where renovation projects call for blunt tip and/or spring-mount base strike termination devices to accommodate architectural requirements or high-traffic roof areas.)
- Ordering a third-party inspection (LPI-IP or UL) to re-certify the system for safety Standard compliance and quality control close-out requirements.
By addressing the above items in a professional manner, the LPS specialist can achieve the ultimate goal of returning the building to the protected zone of a complete system so the expected safety level for the occupants and contents remains continuous.
The science of lightning protection is keeping pace with our ever-changing technology. The newly-released 2017 edition of NFPA 780 includes 12 chapters and 15 annex sections to address design requirements, applications and risk assessment measures for LPS. When designed and installed by a LPI-certified specialist, LPS can meet the needs of safety, technology and design.
