Demising Wall/MC Cable

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mstrlucky74

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Spec says no MC cable in demising wall. From the definition a demising wall is "A separation between two tenants, or between a tenant and a hallway or corridor. The demising wall creates a boundary between two apartments, for example.

So, to confirm, it is those two instances? Thanks.

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mstrlucky74 said:
So, to confirm, it is those two instances? Thanks.
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Sounds like. The only things not covered would be exterior walls and internal partition walls within a unit, whether load bearing or not.
I would double check if possible to see how they consider ceiling if this is a multi-story. That is, is a ceiling below another tenant a demising wall?
Under the definition above it might be. Is it a definition of demising or or demising wall? There is no close quote in your post, so I am not sure where the definition ends.
 
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GoldDigger said:
Sounds like. The only things not covered would be exterior walls and internal partition walls within a unit, whether load bearing or not.
I would double check if possible to see how they consider ceiling if this is a multi-story. That is, is a ceiling below another tenant a demising wall?
Under the definition above it might be. Is it a definition of demising or or demising wall? There is no close quote in your post, so I am not sure where the definition ends.
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Sorry.....for example"
 
: - : - :

A "wall" by definition is in direct relation to a vertical plane.

From the `06 IBC, Ch. 21 - Masonry, Section 2102 -
Definitions: = Wall: " A vertical element with a horizontal
length-to-thickness ratio greater than three, used to enclose
a space."

The "Spec." should have been more explanatory, [ possibly ]
"no MC in tenant separation areas / walls, ceilings or floors,
or another more accurate directive."

: = : = :
 
That's sort of correct. A demising wall does what you say, but a demising wall can also be a rated wall, depending on where it is.

A demising wall between two shops in a shoping center is just a wall, but a demising wall between two apartments is usually sound and fire rated. A demising wall between a B occupancy and an A-2 is usually two hour rated. A wall between a tenent and a "hallway" is probably nonrated, but between a tenent and a "corridor", may or may not be a rated wall.
 
I can understand MC not being allowed to pass through a demising wall. I don't understand the reasoning behind it not being allowed to be used in a demising wall.
 
cowboyjwc said:
That's sort of correct. A demising wall does what you say, but a demising wall can also be a rated wall, depending on where it is.

A demising wall between two shops in a shoping center is just a wall, but a demising wall between two apartments is usually sound and fire rated. A demising wall between a B occupancy and an A-2 is usually two hour rated. A wall between a tenent and a "hallway" is probably nonrated, but between a tenent and a "corridor", may or may not be a rated wall.
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Actually, in my experience a demising wall in a shopping center is often a 2 or 4 hour wall depending on construction. Often done this way to eliminate the requirement for a sprinkler system or fire alarm, by basically creating spaces considered independent. That is what I was first thinking the intent of the specs was. Either way,I agree with others that it is a poorly written spec. Sort of like when they use slang terms for parts prohibition.
 
btharmy said:
I can understand MC not being allowed to pass through a demising wall. I don't understand the reasoning behind it not being allowed to be used in a demising wall.
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I can't tell you why the spec document writer included that, but I can come up with a few SWAGs.

1. Unless conduit is run, modifying wiring later will require opening the wall, which could be an issue in a demising wall.
2. If the formal dividing line between occupancies is in the middle of the wall, conduit could be installed clearly on either side of that line while MC might flop around and cross the magic line.
3. Some misguided concern about fire or other safety by which one tenant's actions could directly affect the other. But that same reasoning would almost require prohibiting all wiring in demising walls. :)

Running anything through the demising wall, regardless of the wiring method used, could create service and access issues, leaving fire protection out of the discussion completely.
 
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