Abstract: A compact, portable cutter device adapted to slit rolls of roofing felt into two or more webs of selective widths for application to a commercial roof. A rigid, box-like external housing is adapted to be supported upon a roof surface near the area where the felt is to be laid. An elongated axle transverses the housing to rotatably secure the roll of roofing felt for cutting. A trough-like cradle is defined within the housing beneath the axle to contain the felt roll. The width of the cradle may be varied by manipulation of suitable end tabs to properly center felt rolls of differing widths. The cradle includes a corrosion-resistant surface to facilitate smooth feeding of the felt fabric from the roll. A rigid, slotted cutter plate defines an interface zone where the cutting assembly is brought into contact with the felt fabric. The cutting assembly includes a plurality of adjustably spaced knives semi-permanently, coaxially mounted upon an elongated, rigid header associated with a foot-powered bell crank.