Are you used portacabins?
In both Australia and the United Kingdom, the word "demountable" in particular refers to portable classrooms.
In the United Kingdom the words "portakabin", "portacabin", "bunkabin" and "terrapin" are commonly used to describe these buildings. However, the use of these words as generic descriptions of portable buildings has caused contention amongst some manufacturers. Spelling with a 'K' is owned by Portakabin exclusively for their products and is a trade mark owned by Portakabin Ltd used to identify its range of re-locatable and modular buildings, and legally should be written with an uppercase P; but "portakabin" or "portacabin" is often used unofficially to mean any portable building of that general pattern. The spelling with a 'c' normally refers to similar temporary buildings made by other companies and Portakabin Ltd argues that the spelling "portacabin" is a misspelling. "Terrapin", like Portakabin, is a portable building manufacturer, although the term "terrapin building" is often used to describe any modular or prefabricated building. The use of “terrapin” dates back further than “portakabin or “portacabin” as the company has been trading for over 60 years. The phrase “terrapin classroom” arose from the sudden need for additional classroom space following the post-World War II baby boom era, and is now common usage for any portable classroom.
In Canada, Australia, and elsewhere, portable buildings are sometimes referred to as "ATCO huts," after the Canadian energy company that manufactures a line of them in one of its business units.