Common roofing term explained by Capital Construction of Brookline MA:Double graveling
As the term implies, it refers to the process of applying two layers of flood coats of aggregate and bitumen to a built up roofing system. Loose aggregate is usually swept up and applied to the second coating.
Brookline roofing FAQ:How long do most built up roofing systems last?
It is not uncommon for homeowners to get upwards of 30 years of use out of their built up roofing systems. In order to guarantee that the rooftop is working as intended, it is recommended for all individuals to call a roofing specialist roughly once a year for a professional inspection.