Zipper codes with irregular variable degree are studied. Two new interleaver maps -- chevron and half-chevron -- are described. Simulation results with shortened double-error-correcting Bose--Chaudhuri--Hocquenghem constituent codes show that zipper codes with chevron and half-chevron interleaver maps outperform staircase codes when the rate is below 0.86 and 0.91, respectively, at $10^{-8}$ output bit error rate operating point. In the miscorrection-free decoding scheme, both zipper codes with chevron and half-chevron interleaver maps outperform staircase codes. However, constituent decoder miscorrections induce additional performance gaps.