What do you call the small cabin on top of roof of certain buildings?

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The small cabin with something on top of it and with pipes running to the top of it. Is there a word for it? What are some standard ways of referring to that thing?

  • Does the cabin contain the stairs down to the rest of the building or is it standalone and only accessed from the other roof entrance/exit?
    – Smock
    Commented Aug 7, 2019 at 9:45

4 Answers 4


The technical term for these structures seems to be either house or bulkhead (e.g. stair/elevator house or stair/elevator bulkhead), but satisfactory online definitions are hard to find.


  1. a boxlike structure built over an opening, as at the head of a staircase, elevator shaft, etc.

Your Dictionary

Elevator house or bulkhead Structures with elevators may have an equipment or motor room located on the roof. Elevator houses vary in size according to the number of elevators that they service...

Fire Engineering's Handbook for Fire Fighter I and II

The term elevator house may well be more understandable than elevator bulkhead to the average person.

  • "The term elevator house may well be more understandable than elevator bulkhead to the average person." Agreed. As a native speaker, when I hear "bulkhead" I immediately think of a ship. I would never have associated that word with a structure like this.
    – MJ713
    Commented Aug 7, 2019 at 1:50
  • Bulkhead appears to be a common architectural term, and has lots of different uses. Basically, it's just an access space above some other structure.
    – Mick
    Commented Aug 7, 2019 at 1:57
  • @Mick Which country are we talking about? Whilst not an architect, I've never heard "bulkhead" used in that context in the UK. Both the online OED Lexico and Merriam-Webster define it as a partition or wall to divide two spaces, not the space itself. Commented Aug 10, 2019 at 14:27
  • Look at the last definition in your MW link.
    – Mick
    Commented Aug 10, 2019 at 15:01

If it contains air conditioning, lift (elevator) motors and similar equipment then it could be called the "plant room". Although a plant room is not confined to the roof of a building, it may be anywhere, such as the basement.


Roof tower, this is just a stair well with a small landing at top of stairs inside.

  • 1
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    – Glorfindel
    Commented Nov 5, 2020 at 21:44

Or Stair tower, can be used to name the structure.

  • Welcome to English Language Learners! While this may be correct, we like our answers to be backed up by references. You can edit your answer to include one (e.g. an online dictionary). See the Help Center article How to Answer.
    – Glorfindel
    Commented Nov 5, 2020 at 21:43

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