A roof grinder is operative to both comminute and transport rubber, asphalt, insulation, rock and other diverse material. The grinder has a cutter which comminutes commercial roofing material. An air transport uses a high velocity air stream to blow the comminuted particles to a collection site on the ground. A rotary air lock couples to the cutter for receiving comminuted roofing material and isolates the cutter from the air transport, to prevent high velocity air from passing through the rotary air lock to cutter. The device is sized for placement on the roof, and has wheels or tracks for easy movement. A flexible hose couples the air transport to a remote location for discharge, such as to a roll-off container. In an alternative embodiment, a roof grinder is operative to both comminute and transport rubber, asphalt, insulation and rock material, and the cutter is operative upon a roof sub-floor to both remove and comminute commercial roofing material.