Walls and Wiring

[williamsmithaud]

A couple of questions:

Question 1

I was recently told by an industrial electrician that (under the NEC regs.) any wire that is run vertically through a residential structure's walls must be must be "sealed air tight" at the points where it penetrates a sole plate, fire block or top plate. He uses a "dab" of spray foam insulation to accomplish this. I was not aware of this requirement, and am not sure if it comes from the 2000 code or the new 2003 code. I also am not sure if it applies only to multiple story structures, or is applicable to single story structures as well. The purpose of the requirement is obviously to prevent a stud chamber from acting as a "chimney" that could draft air, and feed a fire's encroachment to the upper levels of a structure.

I would appreciate any knowledgeable comments on this subject.

Question 2

This applies to structures with hip roofs that join exterior walls. Here in Texas, such homes typically have no basements or crawl space, so access to an exterior wall is limited to the attic. The problem is that there is usually not enough working space in the attic where the hip roof joins the exterior wall. This is true, even when using a flexible drill bit.

My solution is as follows, and I would appreciate any comments:

I cut small holes (approximately 2" x 4") in the sheetrock at the point where the wall and ceiling join. Then I notch the top plates to accept the wire, and pull it down to the device box. I finish by applying a nail guard over the notch, and then patch, texture and paint the sheetrock. Any better ideas?

 

[roger]

Re: Walls and Wiring

William, in regards to your first question, we are required to do the same in N.C. and I know it is a building code requirement not an NEC requirement. It may be part of the IBC or IRC.

In your second question,the way you are doing this retrofit should be fine, this is the same as notching and using nail plates in a new rough in.

The notch would not be allowed to be deep enough to weaken the structural assembly. A joist or supporting beam would be a different story.

Roger

 

[tonyi]

Re: Walls and Wiring

Unless the roof is exceptionally shallow pitch, its usually possible to worm your way out to the edge if you build some ramps across the trusses/joists. You'll be flat on your back doing a worm wiggle to get there, working at arms length, and maybe have some roofing nails pressing into your forehead. BTDT - its doable but rather unpleasant.

 

[pierre]

Re: Walls and Wiring

I have a copy of the 1962 NEC, and firestopping is in the same section and has been since then - 300.21. It was not enforced before, because there was not a listed product for the application.
In New York State it is in the Building code and the NEC and is being strictly enforced. Spray foam won't cut it, as you have to install a listed product. There are now all kinds of listed products, form firewools to batting, to tubes of firestopping. There are even some device boxes that can be installed in a fire wall.

As a matter of fact, the plumbers are installing it, and recently the building officials have been enforcing it with the HVAC contractors - that is creating quite the stir with them .

Pierre

 

[roger]

Re: Walls and Wiring

Pierre, the difference here is that we are not dealing with "fire-resistant-rated" assemblies.

This sealing of holes in plates is for stopping drafts or chimneys within an enclosed wall.

This being the case, fire caulks are not required.

Fire-resistance-assemblies are covered in the UL Fire Resistance Directory (UL Orange Books)

Roger

[ December 06, 2003, 01:20 PM: Message edited by: roger ]

 

[pierre]

Re: Walls and Wiring

300.21
... Openings around electrical penetrations through fire-resistant-rated walls, partitinons, floors, or ceilings shall be firestopped using approved metnods to maintain the fire resistance rating. (2002 NEC)

The intent of 300.21 is that cables, cable trays, and raceways be installed through rated wall, floor, and ceiling assemblies in such a manner that they do not contribute to the spread of fire or the products of combustion. (NEC Handbook)

From the UL General Information for Electrical Equipment - known as the White BOOK.
Fire Resistance Directory - Part VI
Fire Resistance Ratings
Fill, Void, or Cavity Materials (XHHW) The letters XHHW are not to be confused with conductor classification, these are the UL designated letters for their classification.

This category covers fill, void or cavity materials that are proprietary materials installed at the job site in accordance with the application instructions provided with the product and with the instructions specified in the induvidual joint system, perimeter fire containment system or through-penetration firestop system.

Basically what all of the above means is:
If you install a raceway or cable assembly, and it penetrates from one floor level to another, the holes you drilled in the plate(s) and ran your wiring method through are required to be firestopped by an approved method. Horizontal holes drilled through framing members (say 2 x 4s) are not required to be firestopped if they do not penetrate a fire rated wall.
If the vertical run through the wall is greater than 8 feet (say 10 foot ceilings) firestops are required at some point inside this vertical run as well as the penetration of the ceiling/floor plates. There cannot be a span of greater than 8 feet of run in a vertical wall without additional firestopping being added.

Pierre

 

[roger]

Re: Walls and Wiring

Pierre, you're still talking about "rated walls and floors", this is not what is being addressed here.

Here are some rated construction types.


Prefixes to rated assemblies

A Floor-Ceiling Designs-Concrete with Cellular Steel Floor Units and Beam Support

Example; A815

D Floor-Ceiling Designs-Concrete with Steel Floor Units and Beam Support

Example; D218

G Floor-Ceiling Designs-Concrete and Steel Joists

Example; G264

J or K Floor-Ceiling Designs-Precast and Field Poured Concrete

Example; J714

L Floor-Ceiling Designs- Wood or Combination Wood and Steel Joists

Example; L211

N Beam Designs-for Floor-Ceiling Assemblies

Example; N603

P Roof-Ceiling Designs

Example; P244

S Beam-Designs-for Roof=Ceiling Designs

Example; S723

U or V Wall and Partition Designs

Example; U501

X or Y Column Designs

Example; X522

These assembly types play a big part in how we address Fire Proofing.

If you know the assembly design number you can find it here. http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/gfilenbr.html For a trial, punch in any of the example design numbers posted above.

Roger

 

[a.wayne3@verizon.net]

Re: Walls and Wiring

Roger the 2002 building code changes where I am reqiures fire caulk or fire foam not just expandable foam,They have also increased up lift protection from 115 mph to 150 mph,as well as requiring safety glasss on all windows 15 miles or less from the coast or roll down shutters.I guess it depends on where in the country you are

 

[roger]

Re: Walls and Wiring

Allen, you are absolutely right in that local amendments can be installed, but this would have to be done as an amendment to be binding.

We are mandated to build to siesmic specifications here. (earthquake)

Aren't you glad you guys are now under the NEC and not the seperated Florida or South Florida Building Codes?

Roger

 

[pierre]

Re: Walls and Wiring

Roger
Maybe in NC that is not a requirement, but in NY it most definitely is. This is not for sealing the draft, such as in the energy code, but so as to not permit the fire to spread up the walls as the draft created in some of those instances can be surprisingly large helping the fire to escalate at an alarming rate.
These holes are required to be filled with the approved method explained in the prior post.
This requirement is in the Building Code, which in NY as of 2003 is the ICC, so I am sure this is not just a NY State requirement.

Pierre

 

[roger]

Re: Walls and Wiring

Pierre, are all your walls in NY 1,2,3, or 4 hour assemblies?

If they are only privacy/sound rated partitions (which is what is being discussed here) are they handled this way, and if so, what are the code references? Please enlighten me.

Roger

[ December 06, 2003, 08:01 PM: Message edited by: roger ]

 

[pierre]

Re: Walls and Wiring

Roger
Maybe you have misunderstood me or I did not explain it well. I am talking of the penetration between floor levels, not through the walls. The act of installing wiring methods from one floor level to another creates a situation that can lead to fire spreading from one level to another at an accelerated rate if the penetrations are not fire sealed with the approved method.

In NC are the different trades not required to seal the penetrations from one floor level to another?

Pierre

 

[roger]

Re: Walls and Wiring

Pierre, go back and look at my 3:30 post.

I'm sorry, but it appears as though you are deliberately drifting the thread into another situation.

Rated assemblies will be assigned a design type, anything other than that is a curtain so to speak.

Yes in N.C. we comply with all the NFPA codes and more.

In Asheville we have a (enforced) (1) to (1) license to apprentice ratio, so don't entertain the thought that we are backwoods.

N.C. has one of the most stringent qualification requirements(14,000 hrs with supervision hours) for Unlimited licenses (Masters) of all the states.

Roger

 

[pierre]

Re: Walls and Wiring

Roger
I am not trying to argue with you, I am answering what I feel is the point of William's first question.

I was recently told by an industrial electrician that (under the NEC regs.) any wire that is run vertically through a residential structure's walls must be must be "sealed air tight" at the points where it penetrates a sole plate, fire block or top plate. He uses a "dab" of spray foam insulation to accomplish this. I was not aware of this requirement, and am not sure if it comes from the 2000 code or the new 2003 code. I also am not sure if it applies only to multiple story structures, or is applicable to single story structures as well. The purpose of the requirement is obviously to prevent a stud chamber from acting as a "chimney" that could draft air, and feed a fire's encroachment to the upper levels of a structure.
(this paragraph is cut and paste from his post of 11:22 am Dec 6th)

William's first question and my posts seem to be the same topic, there is no intention on my part to make another topic here, thread drifting as you call it.

Pierre

 

[roger]

Re: Walls and Wiring

Pierre, if it's a barrier between two dwellings, be it wall or floor, it will have a rated designation and the conversation changes.

If this is a single dwelling the draft stop is not required to be anything beyond just that.

Do homes in NY have zone seperation?

Roger

 

[hbiss]

Re: Walls and Wiring

Roger, in NY, for any type of residential construction, the holes have to be filled with an approved firestopping material not foam. Doesn't matter what the fire rating of the assembly is if any.

 

[pierre]

Re: Walls and Wiring

Roger
I think I see the confusion here. You are talking about a HORIZONTAL and VERTICAL penetration of rated assemblies (such as the list in your previous post), and I am talking about the VERTICAL penetrations for wiring methods in the framing of the walls, such as the sill plates.
Take a 2 x 4 framed partition before it is sheetrocked, and lets say I need to run a circuit from the basement to the attic of a one story dwelling. I will in the process of installing the cable pass through the first floor plate, through the second floor plate and into the attic. The holes that the cable passes through in those plates have to be firestopped.
I am not disagreeing with the ratings of the assemblies you are discussing, this is a different subject.

Pierre

[ December 07, 2003, 12:50 AM: Message edited by: pierre ]

 

[roger]

Re: Walls and Wiring

Pierre, I have only been referring to vertical penetrations (read my post of 12/6 at 1:18 pm closely) of top and sole plates in non rated assemblies.

Hbiss, points out that the requirement to use a listed fire caulk for this purpose is a NY requirement.

Roger

 

[scott w]

Re: Walls and Wiring

Roger is correct.
There is not necessarily any type of fire resistant construction between floors of a dwelling.
There is no need to caulk penetrations with a fire-rated caulk unless there is a fire rating.
(Pierre, please explain the "envelope" you use for your justification)
Here in CA, nearly all residences are wood framed with 2x4 or 2x6 lumber. The caulking (usually foam used) is required by the energy regulations.

 

[williamsmithaud]

Re: Walls and Wiring

Since my original question deals with one story residental structures of 2 x 4 construction, I'm wondering if the spray foam insulation my friend applies to the cable holes in the sill and top plates is adequate?

This spay foam is commonly available in all home improvement centers. Is there some fire resistant rating I should look for on the label of the foam can?