Abstract: An interlocking roofing system includes, in combination, a plurality of shingles and a plurality of interlock strips. Each of the plurality of shingles includes a planar rectangular body having a first face, a second face, and four sides. Horizontal rows of shingles are interlocked by interlocking a single zigzag reentrant edge on a third side adjacent the second face of one horizontal row of shingles with a double zigzag reentrant edge on a first side adjacent the first face of another horizontal row of shingles. Each of the plurality of interlock strips includes an elongate planar rectangular body having a first face, a second face, and four sides. Shingles are laid in parallel spaced relation with the fourth side of a first shingle adjacent the second side of a second shingle.