Party wall

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hhsting

Senior Member
I have apartment complex with four buildings. Each building is joined adjacent to each other and separated by party wall.

Questions:

1. Is their anything in NEC 2014 that says party walls cannot be penetrated? Wiring, conduits etc etc

2. Are party walls mean each of the four buildings can be considered separate buildings?
 

kwired

Electron manager
Location
NE Nebraska
Never heard the term party wall.

Guessing it is at least a 2 hour rated wall where most the partitions between individual apartments and/or common areas are otherwise only 1 hour walls?
 

tom baker

First Chief Moderator
Staff member
1. This is a building code issue
Need to modify answer. There is a UL Guidebook on this, maybe fire resistance directory. It covers wiring boxes in firewalls, ie how close together they can be, etc. So its somewhat in the code.
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
I have apartment complex with four buildings. Each building is joined adjacent to each other and separated by party wall.

Questions:

1. Is their anything in NEC 2014 that says party walls cannot be penetrated? Wiring, conduits etc etc

2. Are party walls mean each of the four buildings can be considered separate buildings?
#1. My only experience with this type has been a fire codes issue not NEC, it was a large multi-story apt condo complex type. Where it intersects the NEC is related to box construction, conduit or MC, fire barrier wrapping on boxes, and box seal for smoke penetration prevention on any electrical or wall penetration on adjoining unit walls, also couldn't have the breaker panel on the adjoining walls. Another job was requiring a 4 hr fire rating on adjacent walls, even the attic space requires seperation. Another job addressed the fire rating issue by having in effect 2 walls, with double rock in center of, inbetween the 2 walls, they also had studding staggered for sound transfer reduction. They also didn't allow branch circuits to migrate between the units even on the common wall.
#2. Not sure the NEC sees this as seperate buildings for allowing seperate service drops, believe it still viewed as a single building and a single service. If that is why you ask.
 

hhsting

Senior Member
IBC defines it as following:

706.1.1 Party Walls

Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

Exception: Openings in a party wall separating an anchor building and a mall shall be in accordance with Section 402.7.3.1.



Below is definition of building NEC 2014:

2014 Code Language:

Building. A structure that stands alone or that is cut off from adjoining structures by fire walls with all openings therein protected by approved fire doors.




So really would not parting wall between four adjoining building from top to all the way to roof not be considered four separate buildings?
 

Eddie702

Licensed Electrician
Location
Western Massachusetts
Occupation
Electrician
IBC defines it as following:

706.1.1 Party Walls

Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

Exception: Openings in a party wall separating an anchor building and a mall shall be in accordance with Section 402.7.3.1.



Below is definition of building NEC 2014:

2014 Code Language:

Building. A structure that stands alone or that is cut off from adjoining structures by fire walls with all openings therein protected by approved fire doors.




So really would not parting wall between four adjoining building from top to all the way to roof not be considered four separate buildings?
I think you found your own answer
 

hhsting

Senior Member
#1. My only experience with this type has been a fire codes issue not NEC, it was a large multi-story apt condo complex type. Where it intersects the NEC is related to box construction, conduit or MC, fire barrier wrapping on boxes, and box seal for smoke penetration prevention on any electrical or wall penetration on adjoining unit walls, also couldn't have the breaker panel on the adjoining walls. Another job was requiring a 4 hr fire rating on adjacent walls, even the attic space requires seperation. Another job addressed the fire rating issue by having in effect 2 walls, with double rock in center of, inbetween the 2 walls, they also had studding staggered for sound transfer reduction. They also didn't allow branch circuits to migrate between the units even on the common wall.
#2. Not sure the NEC sees this as seperate buildings for allowing seperate service drops, believe it still viewed as a single building and a single service. If that is why you ask.
I have similar situation where I have apartment complex. All buildings are adjoined together and in between each is party wall. So let’s say I have bldgs 1, 2,3,4,5,6. Between bldg 1 and bldg 2 party wall, between bldg 2 and bldg 3 party wall etc etc


Their is electrical room in bldg #3 and meter stacks. Guess what they have feeders going from the bldg #3 meter stacks all the way up in attic and then penetrating party wall to go to bldg #4, bldg #5, bldg #1, bldg #2 dwelling units.

So that’s why I was wondering if their is anything in the NEC 2014 that would prevent penetrating party walls or it is allowed by NEC 2014 with some approved fire proof or door etc? If it’s IBC issue then I don’t care but if it’s NEC issue boy that gotta change it alright
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector
If you think the NEC is confusing, wait until you start looking at the numerous UL fire proofing systems. Most of what you are looking at, as noted, is building Code issues. "Fire wall" in building terms is like saying "ground" in electrical..there's a lot more involved such as the rating of the wall (1 hr, 2 hr, 4 hour)
I would think step 1 is to determine the rating (normally a building official or engineer's job. Once that's in place then you look at the location of any openings and penetrations to assure the electrical is properly rated.
There is huge liability involved so the decisions often need to be made by professionals such as architects or engineers.
 

kwired

Electron manager
Location
NE Nebraska
I have similar situation where I have apartment complex. All buildings are adjoined together and in between each is party wall. So let’s say I have bldgs 1, 2,3,4,5,6. Between bldg 1 and bldg 2 party wall, between bldg 2 and bldg 3 party wall etc etc


Their is electrical room in bldg #3 and meter stacks. Guess what they have feeders going from the bldg #3 meter stacks all the way up in attic and then penetrating party wall to go to bldg #4, bldg #5, bldg #1, bldg #2 dwelling units.

So that’s why I was wondering if their is anything in the NEC 2014 that would prevent penetrating party walls or it is allowed by NEC 2014 with some approved fire proof or door etc? If it’s IBC issue then I don’t care but if it’s NEC issue boy that gotta change it alright
If the intention is to create "separate buildings" then you have violations of sections in art 225 part II by feeding some those buildings through other buildings, and if more than one occupancy in each "building" you also have violations of number of feeders supplying each building.
 

hhsting

Senior Member
If the intention is to create "separate buildings" then you have violations of sections in art 225 part II by feeding some those buildings through other buildings, and if more than one occupancy in each "building" you also have violations of number of feeders supplying each building.
I don’t understand. NEC 2014 section 225 is for outside feeders but these are inside the buildings Not outside feeders. They don’t go outside. Also you still have penetration even though one feeder thru party wall.

Does multi tenant commercial buildings with firewalls separation each tenant consider different buildings and fed from feeders in electrical room be also then have same section applied 225 but does it really work that way?
 

kwired

Electron manager
Location
NE Nebraska
I don’t understand. NEC 2014 section 225 is for outside feeders but these are inside the buildings Not outside feeders. They don’t go outside.

Does multi tenant commercial buildings with firewalls separation each tenant consider different buildings and fed from feeders in electrical room be also then have same section applied 225 but does it really work that way?
Part II is for branch circuits or feeders supplying separate buildings or structures and potentially applies to what you have.

The building code wants these walls with probably at least a 2 hour rating to make them essentially same thing as separate buildings, including appropriately rated fire doors in any openings between them. This makes emergency situations similar to as though they were separate buildings when it comes to egress and prevention of fire/smoke spread. Does it make sense to shut down and evacuate unit 2 because of a fire, only to still have unit 1 supply conductors still live inside unit 2?
 

hhsting

Senior Member
Part II is for branch circuits or feeders supplying separate buildings or structures and potentially applies to what you have.
Scope of 225 NEC 2014 below regardless of 225 parts I, II, III etc. It does not say feeders run in buildings which is what I have and says outside feeders run between bldgs. So how can NEC 2014 section 225 apply here?


 

kwired

Electron manager
Location
NE Nebraska
Scope of 225 NEC 2014 below regardless of 225 parts I, II, III etc. It does not say feeders run in buildings which is what I have and says outside feeders run between bldgs. So how can NEC 2014 section 225 apply here?


Because you effectively created separate buildings even though the "outside part" is only a fine line in width.

encase the feeders in 2 inches of concrete and those feeders might be effectively considered "outside the building" in a similar manner as to how each section is considered a separate building.
 

kwired

Electron manager
Location
NE Nebraska
Is party wall really 2 inch of concrete or something else?
IDK for certain on that. 2 inch encasement of service conductors or other similar situations like being in a vault generally is acceptable to consider them outside the building. But this mostly pertains to electrical considerations and not everything else that other building codes uses to consides a separate building or effective equivalent.
 
I think you are correct, article 225 does not apply to your situation. I am not sure if that is what the intent was, but that is the way I read it. As Kwired said, I suppose one could argue that if you are exiting one building and entering another, then at some point you are "outside" of one of the buildings 🤔
 
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