Modified bitumen

Modified bitumen has been the workhorse of NC commercial flat roofing since the 1980s. A well-installed two-ply SBS system can last 15 to 20 years. Torch-applied APP is more common on older buildings; newer work often uses self-adhering SBS to eliminate the open-flame fire risk during installation. The failure modes are predictable: dried-out and brittle lap seams, blistering from trapped moisture between plies, and corner splits where thermal cycling has stressed the membrane repeatedly over many years.

On a storm claim involving modified bitumen, the key task is distinguishing storm damage from normal aging. Storm damage looks like impact splits from hail, wind-lifted seams at the perimeter, and displaced gravel ballast. Normal aging looks like surface oxidation, hairline cracking from thermal fatigue, and blistering from trapped moisture. We document both clearly and separate them in the scope: storm damage goes on the claim; existing deficiencies go on a separate condition report so the building owner has a complete picture.