This installation tip was provided by Kate Collardson, solar services manager, CertainTeed
When installing solar on a home, one of the most important steps is the installation of flashings. With dozens of penetrations to the roofing system per array, proper flashing and its subsequent installation is critical to the integrity of the roof. Poorly designed, manufactured or improperly installed flashings will lead to roof leaks, which can cause interior water damage and mold growth and cause headaches for years down the road.
Whether it’s a plumbing vent, chimney stack or solar mount, any penetration of the roofing system needs to be properly flashed. When installing solar mounts on an asphalt shingle roof, flashings should be installed so the top extends under the third course of shingles to cover cutouts or butt-joints between shingles. The bottom of the flashing should not hang below the bottom edge of the course of shingles it rests on. Pilot holes should be backfilled with a quality roofing-grade sealant, and lags should not be over-tightened to avoid causing the flashings to dimple. Installers should gently pry up the shingles when installing the flashing to prevent shingle damage. Shingles should be sealed to the flashing to resist being blown off later in high winds. For tile roofs, penetrations should be flashed at both the tile level and the underlayment level.
In the end, homeowners want to be assured their solar investment won’t cause damage to their homes. Homeowners and installers would be wise to ensure that well-designed, high-quality flashing and sealants are used and that both the flashing and any applicable roofing manufacturer’s installation instructions are always followed. Product warranties offer good protection now that most flashing comes with a 25-year warranty. Installation workmanship warranties, such as CertainTeed’s Gold Warranty that covers the installation of the flashing for up to 25 years, offer the best protection.