Officially/technically, they are casemate ironclads, basically because it was just that - a floating casemate (a fortified gun emplacement or armored structure from which guns are fired, as part of a fortification) covered with iron plate.
From what I can gather, only the top half was ironclad, the hull beneath the waterline was not. Any ram was metal or metal-plated, but, it seems, the rest was not. Even the revolutionary Dunderberg had plate to just 5 feet below the waterline. One of the justifications for the low deck, apart from a small target, was that most of these vessels were for use on estuaries and rivers and many were converted river steamers, both side- and stern-wheelers.
Offshore ironclads had a higher freeboard to cope with the higher seas. These were NOT iron-hulled ships, but constructed of wood with iron plate on top. The first iron-hulled ironclad was the RN frigate HMS Warrior (1861), but with armor plate added on top of the iron hull. Having said that, all iron plates were backed with wood, often in a number of layers.
en.wikipedia.org
Bringing the