Application and/or installation of asphalt,
pitch, tar, felt, flax, shakes, shingles, roof tile, slate, and any other material or
materials, or any combination of any thereof which use and custom has established as
usable for, or which are now used as, water-proof, weatherproof, or watertight seal or
membranes for roofs and surfaces; and roof conversion. Incidental work includes the
installation of roof clamp ring to the roof drain.