The ships' waterline belt consisted of Krupp cemented armour (KC) that was thick between the main gun barbettes and thinned to over the engine and boiler rooms as well as the six-inch magazines, but did not reach either the bow or the stern. To improve its ability to deflect plunging fire, its upper edge was inclined 18° outward. The ends of the armoured citadel were closed off by transverse bulkheads of non-cemented armour thick at the forward end and thick at the aft end. The faces of the main-gun turrets were protected by 16-inch of KC armour while the turret sides were thick and the roof armour plates measured in thickness. The KC armour of the barbettes ranged in thickness from .