While there is no single standard height for wainscoting in a bathroom, the typical height range is from 38-to-42 inches off the ground, or taller than the vanity or sink.A height range of 48-to-54 inches is also common, since the higher the wainscoting, the more protection it offers.athroom wainscoting keeps water from damaging the lower parts of walls. Wainscoting in the bathroom is decorative, but it also helps protect the walls from splashes of water, especially near the sink.