When a Roofing System Provides More Than Waterproofing
Today more than ever, roofing systems are expected to perform functions well beyond the original intention of waterproofing. Changing lifestyles, the need for alternative energy sources, expanded living spaces and a greener, healthier planet are pushing roofing systems — and the membranes that keep the contents of a building dry — to multi-task and go beyond their traditional function as waterproofing membranes. When an “overburden” (i.e., additional materials placed over a majority of the roof membrane) is desired, choosing the right roofing system plays an integral role in waterproofing.
Solar, garden and recreational systems are transforming the traditional purpose of roofing systems. These systems are rising in popularity, driven by voluntary programs such as LEED (Leadership in Energy and Environmental Design), regulatory changes like California’s Title 24, local government and power company incentives, and a growing desire to gain more livable space. While all these systems require special attention to the roof membrane in order to maintain their primary design role as a waterproofing system, each overburden has unique needs of its own.
Modifying a roofing system to include solar components requires a great deal of planning, so a roofing professional should be consulted to evaluate the age and condition of the membrane. Due to its inherent durability, bituminous membrane roofing is well suited as a platform for solar photovoltaic (PV) systems, provided that proper design, installation and maintenance are practiced. Solar components, whether rack mounted PV systems, or adhered thin film or flexible PV systems (also referred to as building integrated or BIPV), can create stress on the membrane. Taking precautions in the planning stage of the original membrane installation can reduce damage to the membrane and ensure the roofing system performs as expected.
With BIPV systems in particular, there is the potential for accelerated aging caused by increased heat loading and higher degrees of thermal cycling. When considering a PV system, be sure to consult the membrane manufacturer as they may have specific system recommendations including, but not limited to, a requirement for frequent inspections to monitor the effects of the PV system on the membrane, or the inclusion of an isolation sheet or surface coating in the conjunction with the PV system to help ensure continued performance.
In addition, if a rack mounted system is selected, multiple penetrations may be a part of the installation. As with any roofing system where multiple penetrations are present, attention to proper waterproofing details is critical to a leak-free installation. The Asphalt Roofing Manufacturers Association (ARMA) provides safety and product handling guidance for installing PV systems on low-slope commercial roofs. To download the ARMA Technical Bulletin, please click here.
Asphalt roofing provides durable and reliable protection from ”overburdens,” and can be easily maintained and repaired when necessary. Photo Credit: ProTech Roofing Industry standards such as those developed by Underwriters Laboratory and FM Global (PLPDS 4476 and 4478) for wind and fire performance provide guidelines that help ensure the placement of a PV system. They allow the complete roofing system, both the waterproofing membrane and the overburden, to perform as expected.
Model code developers are recognizing the need to keep building and energy codes up to date to ensure that new technologies such as roof-mounted solar PV systems and vegetative roofing materials meet other code requirements. For example, the International Code Council (ICC), which publishes the International Codes, now includes provisions for these types of systems. The 2012 International Building Code (IBC) contains requirements for solar PV systems to comply with fire classifications and wind resistance requirements, and newly enacted provisions for solar PV shingles will be included when ICC releases the 2015 International Energy Conservation Code (IECC). The 2012 International Green Construction Code (IgCC) contains detailed provisions related to vegetative roofing systems (aka “green roofs”). As these technologies become more popular, regulatory requirements including product performance features and installation provisions will become more widespread.
Property managers and owners should be aware that with the installation of solar panels, a roofing membrane is asked to do more than just provide waterproofing. Additional safety practices must be a part of the ongoing care and maintenance of the roofing system.
An 11-alarm fire in early September that gutted the Dietz & Watson warehouse in Delanco, NJ, highlighted the urgent need for planning and communication with emergency services when the roof area is used as an energy gathering/producing environment. According to a news report by WPVI-TV, an ABC affiliate in Philadelphia, PA, containment efforts on the large roof, which was greater than six football fields, were slowed because of the presence of energized solar panels.
In a 2010 study by the National Fire Protection Association Research Foundation titled, “Fire Fighter Safety and Emergency Response for Solar Power Systems,” key concerns were outlined about emergency response in the event of a fire where solar panels are in place, expressing particular concern about their presence on large commercial properties.
The NFPA study, which was revised in October 2013, summarized 12 key issues that impact emergency response to a building where solar panels are in place producing power. They share that…
That the roof is always hot… in sunlight hours and even in nighttime hours when battery storage systems are in place.
Stress key message for tactical approach (especially large commercial systems)… stress with all fire ground personnel (i.e., stay clear). Serious injury can occur with equipment such as photovoltaics on a sunny day, and the danger to fire service personnel is real and deserves attention. Of paramount concern are large commercial PV systems that generate significant levels of electricity and can create daunting strategic challenges for fire fighters as they are trying to address a building fire.
They also reference some basic safety protocols on emergency preparedness that both owners and property managers can incorporate to help ensure the lives of emergency personnel are protected in the event of a fire.
Create consistent placarding and labeling for emergency responders. Standardized approaches to provide consistent identification of solar power systems and their components would greatly assist emergency responders in safely completing their job performance tasks. In particular, clearly and consistently identify system components that require special attention during an emergency, such as the color-coding of an electrical conduit that is normally energized for a PV system. The more universal the identification protocol, the more likely for it to be embraced by the mainstream fire service.
Address on-going maintenance oversight of installed systems (especially commercial). On-going operation and maintenance concerns for solar power systems must be addressed. These systems are normally exposed to outdoor weather conditions that enhance the aging process, and the infrastructure needs to be in place for the on-going maintenance of these systems to assure their safe operation.
Require system contact information for emergencies. Consideration needs to be given to establishing responsible points of contacts that emergency responders can reliably depend on during an emergency situation. They currently have such contacts for other building systems they must handle, such as a building’s electrical connection from the local power grid, or an automatic sprinkler system. In similar fashion, they should know who they can reliably use as an additional resource during an emergency, and who can readily assist with stabilizing the system. This is especially important for large commercial photovoltaic systems.
For more information on the incorporation of solar panels into your roof system contact the manufacturer of your roofing system and review the complete NFPA report online. For more information about ARMA or asphalt roofing, visit www.asphaltroofing.org.