Appeal 33603

Section 13.4 of ASCE 7-16

NONSTRUCTURAL COMPONENT ANCHORAGE
Nonstructural components and their supports shall be attached
(or anchored) to the structure in accordance with the requirements of this section, and the attachment shall satisfy the requirements for the parent material as set forth elsewhere in this standard. Except where permitted in Section 13.6.12, component attachments shall be bolted, welded, or otherwise positively fastened without consideration of frictional resistance produced by the effects of gravity. A continuous load path of suf?cient strength and stiffness between the component and the supporting structure shall be provided. Local elements of the structure, including connections, shall be designed and constructed for the component forces where they control the design of the elements or their connections. The component forces shall be those determined in Section 13.3.1. The design documents shall include suf?cient information relating to the attachments to verify compliance with the requirements of this section

The roof at the Grace Peck building is an existing modified SBS flat roof with a proposed PV solar array which requires servicing at times. The proposed counterweighted (ballasted) guardrail provides protection to personnel for servicing this equipment that is within 10’ of the edge of the roof.

The existing roof of the Grace Peck building is a flat roof sloped only for drainage, see Appendix D. The roof is a modified SBS roof system that would create a potential water intrusion problem if the existing roof were partially pulled back for the mounting.
The roof is accessed by a rooftop hatch which is locked and accessible only by maintenance staff. The proposed design for the guardrail will be a new 42” high counterweighted (ballasted) guardrail system at the full roof perimeter to provide protection for maintenance of the roof top PV solar array. ASCE 7-16, Section 13.4 requires items to be mechanically fastened that are non-structural. The proposed guardrail meets the requirements of 2022 OSSC 1015.6.
Equivalent protection is provided by the ballasted guardrail system being tested to meet the requirements for personal safety per OSSC 1607.9.1 (see attached reports) and the guardrail is surrounded by a 2’ high parapet.

The Grace Peck building is six stories tall with an existing modified SBS roof. There will be a ballasted new solar array, see Appendix - E, which is compliant with and permitted by ASCE 7-16 §13.6.12. The guardrail system will provide safe access to service the new solar array and is designed with 47 stanchions which provide the required 200 lbs. live-load support (see attached reports).
ASCE 7-16 §13.4 requires non-structural elements to be mechanically fastened, without the exception the PV panels have for a ballasted securement system. Mechanically fastening the guardrail system, each stanchion location would need to have the rigid insulation cored through for an attachment to the concrete deck below. This would require a significant number of penetrations through the existing modified SBS roof system, creating the potential for water intrusions in each of the 47 locations. See plan below.
The guardrail system is designed to resist movement and is weighed down with 85 lb. ballasts at each stanchion location, see appendix A for system specifications and layout. Each rail is a maximum of 10 feet in length. This counterweighted guardrail system has been tested to withstand 200 lbs. point-load without deformation or deflection, see appendices B and C for test data. The guardrail system is fully located within the bounds of a perimeter parapet that surrounds the roof, see Appendix F.
ASCE 7-16 §13.4 requires that non-structural components be mechanically fastened without consideration for frictional resistance in order to keep such elements in place, specifically during seismic events. The system has been tested and will resist movement under normal operational circumstances. In the event of a large scale earthquake or other significant horizontal forces, the 24” high parapet that encompasses the entire guardrail and PV systems provides a physical barrier preventing the system or any of its components from falling off of the roof. The combination of the counterweighted guardrail and the perimeter parapet provides equivalent protection to that of a mechanically fastened guardrail required by ASCE 7-16 Section 13.4. We request approval of this appeal to utilize the counterweighted guardrail system.