Wet rooms can take a number of forms.  From walk in showers in sporting venues, to enable shower rooms to be accessible by disabled persons in a domestic or hospital/residential location and rooms to be used by service people such as in the image shown, a changing room for lifeboat service persons.  The method used is known as tanking whereby in the case of a shower room, walls and floors are made waterproof by covering with a waterproof material such as tiles or plastic sheeting on walls and safety flooring.  A sub floor is created to allow for a gradient along the floor to channel water via a drain inserted in the floor to enable flow of water from the room  Safety flooring is plastic welded on joins In the image shown to create a complete floor ‘tank’.