Washboard (WB) modes are a very regular phenomenon commonly observed in JET H-Mode discharges, appearing as broader bands of bursting magnetic fluctuation at the plasma edge. It will be shown that WB modes are deeply involved in the pedestal dynamics, affecting the pedestal build-up through inter-ELM losses. In close relation to this, the time between consecutive type-I ELMs increases with WB mode strength. A class of type-I ELM precursors commonly observed in JET [C P Perez et al, to be published in Nucl. Fusion] is found to interact with WB modes: With the onset of type-I ELM precursors the WB modes become weaker or are even inhibited, resulting in an acceleration of the pedestal pressure build-up. WB activity is found to increase with gas puffing at high triangularity, and can explain the recently identified mixed type-I/type-II ELM regime on JET. A modified version of the peeling-ballooning cycle for type-I ELMs, that takes into account the physics of WB modes, is proposed.