Maintaining Lightning Protection Systems During Reroofing and Building Envelope Modernization

For engineers, architects, and building specifiers, the integrity of a structure’s lightning protection system (LPS) is paramount. While most components of an LPS are designed for longevity, routine building maintenance, particularly reroofing projects, necessitates careful consideration to ensure continuous, code-compliant protection. Disruptions to the building envelope during roof maintenance can compromise the effectiveness of an existing lightning protection system, requiring precise planning and execution to restore its protective capabilities.

Critical Components of Rooftop LPS

A comprehensive lightning protection system routes powerful current safely from a strike point to the ground. On the rooftop, key components include:

• Strike Termination Devices: Primarily air terminals (lightning rods), these intercept direct lightning strikes, protecting the building and rooftop equipment.
• Conductors: Large-diameter, multi-strand cables that interconnect strike termination devices and guide the current to down conductors.
• Through-Structure Assemblies: Specialized fittings allowing conductors to pass safely through the roofing system, insulation, and roof deck to connect with the grounding system.

All these components, along with various fittings and fasteners, must be UL-listed and installed in strict adherence to industry standards, notably NFPA 780 – Installation of Lightning Protection Systems and related Lightning Protection Institute (LPI) standards, including UL 96A.

The Imperative of Certified Expertise and Standards Compliance

The National Roofing Contractors Association (NRCA) explicitly states that the installation, evaluation, and maintenance of lightning protection systems are beyond the expertise of most roofing contractors. It is crucial that all lightning protection work, especially during reroofing, be performed by LPI-certified professionals. Unqualified work can lead to severe defects, such as improperly secured conductors or inadequate bonding, which compromises the entire system’s effectiveness and can void its certification.

To ensure system integrity, a three-pronged approach is essential:

1. Design: The system must be engineered in accordance with recognized standards (NFPA 780, LPI, UL 96A).
2. Installation: Work must be executed by certified installers and contractors.
3. Acceptance: The completed project must undergo inspection and certification (or recertification) for compliance.

Strategic Planning for Seamless LPS Integration During Reroofing

Effective coordination between roofing and lightning protection professionals is vital. Before any roof demolition, an LPI-certified professional should conduct a thorough assessment, measuring and marking the exact locations of existing thru-roof assemblies. This foresight prevents complications once new roofing is installed.

During this phase, a decision must be made regarding existing LPS components: salvage and reuse or replace with new. While salvaging can seem economical, new UL-listed components often provide better compatibility, easier installation, and guaranteed compliance with current standards. Old components, typically made of high-grade copper, brass, and aluminum, can often be recycled.

For occupied buildings, especially those housing mission-critical or highly combustible materials, implementing temporary lightning protection measures during any hiatus in the permanent system is a critical safety consideration. Furthermore, diligent coordination is required with other trades (e.g., HVAC, plumbing) and roofing manufacturers to ensure that all rooftop appurtenances are properly integrated and equipotential bonding is achieved. All metal fabrications, including parapet copings and flashings, must be bonded to the LPS to prevent dangerous arcing during a lightning event, enhancing overall building envelope protection.

Restoring and Certifying LPS Post-Reroofing

Reroofing presents a unique opportunity for building owners to have their entire lightning protection system inspected and updated. Even parts not directly affected by the reroofing should be checked for damage or degradation. Post-reinstallation, achieving certification through programs like the Lightning Protection Institute Inspection Program (LPI-IP) is paramount. For previously certified buildings, an LPI-IP Reconditioned Master Certificate signifies that the complete system meets current standards, reinforcing the structure's safety and value.

Source:
Reroofing and Lightning Protection
Building Enclosure, March 2022