A hob must be built from a water-resistant material (masonry, concrete, or metal that will not corrode); AAC blocks are acceptable with internal membranes if primed first. Gaps, joints and intersections are made flush before membrane, the hob is secured to the floor and sealed to the wall before an internal membrane, and its top falls toward the shower. Timber hobs are prohibited.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.