The Columbia river steamer Mascot. The built up cabins aft of the open front deck are collectively called the "house."
House is a steamboat term referring to the cabin structure of a steamboat. Generally the house includes every structure on steamboat built above the first deck, which is usually called the freight deck or the engine deck.
References
Affleck, Edward L. (2000). "Preface: Glossary of Terms". A Century of Paddlewheelers in the Pacific Northwest, the Yukon, and Alaska. Vancouver, BC: Alexander Nicholls. 3. ISBN0-920034-08-X.