Walls divide rooms but what do you call what divides stories?

Looking from below it would be the ceiling, looking from above it would be the floor. But when looking at it from the outside? Is there a common word?

I am looking for a word which describes structures that divide a space vertically as opposed to walls which divide the space horizontally.

  • 5
    The problem with asking for a neutral term between ceiling and floor is that they aren't always two sides of the same coin. Especially in multi-story buildings, there's often a space between the ceiling and the floor above (cf. interstitial space). Of the two, the floor is definitely the more important and the better built--he floor has to be safe to walk on, while the ceiling is just there to conceal whatever is above (and under the floor)--so perhaps the answer below that suggests floor is the best for your purposes.
    – Wlerin
    Aug 18, 2014 at 16:37
  • Mathematically speaking, "plane" would be the word, but I don't know if that's too abstract for what you need.
    – Joe
    Oct 20, 2022 at 0:12

7 Answers 7


Believe it or not, the word you are looking for is floor.

It refers to both the space between and the actual divisions. But the space between can have other names like story ("storey" in British English).

If it were a house it would be the roof.

I think you could use "floor slab" or deck.

enter image description here


The actual word for a vertical partition between two stories is called a Party Structure.

Wanted to create a different answer because my other answer was related but different.

  • NOTE: This word is used more in the UK than it is in the US.

Party Structure Diagram

Vertical Partition

  • @RomanReiner Hopefully this helps
    – Adam
    Aug 18, 2014 at 15:16
  • 4
    Party structure also covers walls, fence walls etc.
    – ermanen
    Aug 18, 2014 at 15:20
  • 1
    A party structure divides separate apartments--be they vertical or horizontal. And a detached single family home wouldn't have any party structures.
    – DA.
    Aug 18, 2014 at 20:08
  • this just sounds like a british-ism for "partition" to me
    – user428517
    Aug 19, 2014 at 2:15
  • @sgroves have you tried googling 'partition'?
    – OJFord
    Aug 19, 2014 at 3:14

You could use the word Partition. It is even more general and doesn't specify vertically or horizontally. It defines an object which separates something into parts.

So: For a building, a partition separates the building into floors, stories, rooms, or whatever your preference is. As TheFreeDictionary.com says,

partition: a division into parts; separation

  • 1
    Thanks for the answer. However, I need a word which specifically describes vertical partitioning because I have both vertical and horizontal walls/partitions and need to distinguish between them preferably without using the words horizontally and vertically all the time. Aug 18, 2014 at 15:02
  • @RomanReiner Can it be a word to describe a vertical partition of something other than walls/a building? Like a word that describes a vertical partitioning of something else but you could redefine the word to others as that?
    – Adam
    Aug 18, 2014 at 15:11
  • It doesn't need to be walls/building specifically I just thought that would be a good image. The important things are that the word describes the structure dividing the space and not the divisions themselves and that there are separate words for horizontal and vertical walls. Aug 18, 2014 at 15:18
  • when i hear "partition" in regards to a building, i immediately think vertical.
    – user428517
    Aug 19, 2014 at 2:14
  • I agree with @sgroves - but not only vertical, I think not-original (if house is older than a couple decades) and not-solid. 'Partition' is used for vertical.. partitions made from wood and plasterboard, the superset (IMO) 'wall' includes those made from masonry.
    – OJFord
    Aug 19, 2014 at 3:13

A common English term is stories:

"This building is seven stories tall."


and alternative is floor:

"All the bedrooms are on the fourth floor."

See 3-A

  • 2
    A story would be the space between two [word I am looking for]s. [Word I am looking for] would be the structure between two stories. Aug 18, 2014 at 15:03
  • @RomanReiner See my EDIT#1 Aug 18, 2014 at 15:06

How about layer? Or dividing layer Or separating layer — something like that?

Stratum is related to layer, but I think layer is less scientific sounding.


I think this may be what you're looking for: Definition from WhatIs.com searchdatacenter.techtarget.com/definition/plenum

In building construction, a plenum (pronounced PLEH-nuhm, from Latin meaning full) is a separate space provided for air circulation for heating, ventilation, and air-conditioning (sometimes referred to as HVAC) and typically provided in the space between the structural ceiling and a drop-down ceiling, or between floors.

  • 1
    but the word you suggests refers to the space and not to the division which the question asks for.
    – gelolopez
    Jun 15, 2015 at 19:31
  • Plenum is not a hypernym for floor and ceiling. Jun 15, 2015 at 21:26

If you look at Wiki, for architectural use, the phrase you're looking for is " "Interstitial space".


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