There is no specific standard when it comes to solar PV and flashing, but it’s understood that flashing must be installed in a way to prevent water intrusion. The 2015 IBC code says to follow individual shingle manufacturers’ instructions, and many roofing manufacturers refer to best practices and guidelines from the Asphalt Roofing Manufacturer’s Association (ARMA) and National Roofing Contractors Association (NRCA).
The current recommendation from NRCA for steep slope, pitched asphalt roofs suggests applying a pipe flashing to solar mounting structures. The pipe flashing upper flange must slide underneath the underlayment. A good sealant compatible with the roof with the highest operating service temperature is also necessary. Good design with proper thermal splicing can make this type of attachment last longer with few issues.
A benefit to installing quality, integrated flashing—such as the butyl rubber used with Roof Tech’s RT-[E] Mount—is that it doesn’t disturb the seal of the asphalt shingles. Breaking the shingles’ seal can have an impact on the roof’s warranty of the asphalt roofing product. Wind damage and sealing failure can degrade the terms of a roofing warranty.
RT-[E] Mount is anchored to either the decking or rafter, with mounting screws pushing through butyl rubber flashing for a waterproof seal. The mounting screws are not much bigger than the nails used to secure the asphalt shingles, and the system is automatically flashed and sealed. For this reason it can’t and shouldn’t be flashed with conventional pipe flashing—avoiding voided roof warranty concerns.
This installation tip was provided by Milton Nogueira, senior business development manager, Roof Tech