# Noncommunicating stud cavities



## chris kennedy (Oct 11, 2013)

What is meant by that as seen in IBC 713.2? Would the factory punched holes in metal studs allow cavities to 'communicate'?

Thanks


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## mtlogcabin (Oct 11, 2013)

Are you sure about the code section? What year?

They are different subjects between the 09 and 12 editions


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## chris kennedy (Oct 11, 2013)

2009........


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## Gregg Harris (Oct 11, 2013)

713.3.2 exception 1 under Membrane Penetrations?


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## steveray (Oct 11, 2013)

713.2 Installation details. Where sleeves are used, they shall be securely fastened to the assembly penetrated. The space between the item contained in the sleeve and the sleeve itself and any space between the sleeve and the assembly penetrated shall be protected in accordance with this section. Insulation and coverings on or in the penetrating item shall not penetrate the assembly unless the specific material used has been tested as part of the assembly in accordance with this section.

???????


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## Gregg Harris (Oct 11, 2013)

713.3.2 Membrane penetrations. Membrane penetrations shall comply with Section 713.3.1. Where walls or partitions are required to have a fire-resistance rating, recessed fixtures shall be installed such that the required fire-resistance will not be reduced.

    Exceptions:

    1. Membrane penetrations of maximum 2-hour fire-resistance-rated walls and partitions by steel electrical boxes that do not exceed 16 square inches (0.0103 m2) in area, provided the aggregate area of the openings through the membrane does not exceed 100 square inches (0.0645 m2) in any 100 square feet (9.29 m2) of wall area. The annular space between the wall membrane and the box shall not exceed 1/8 inch (3.1 mm). Such boxes on opposite sides of the wall or partition shall be separated by one of the following:

 1.1. By a horizontal distance of not less than 24 inches (610 mm) where the wall or partition is constructed with individual noncommunicating stud cavities;



    1.2. By a horizontal distance of not less than the depth of the wall cavity where the wall cavity is filled with cellulose loose-fill, rockwool or slag mineral wool insulation;

    1.3. By solid fireblocking in accordance with Section 717.2.1;

    1.4. By protecting both outlet boxes with listed putty pads; or

    1.5. By other listed materials and methods.

    2. Membrane penetrations by listed electrical boxes of any material, provided such boxes have been tested for use in fire-resistance-rated assemblies and are installed in accordance with the instructions included in the listing. The annular space between the wall membrane and the box shall not exceed 1/8 inch (3.1 mm) unless listed otherwise. Such boxes on opposite sides of the wall or partition shall be separated by one of the following:

    2.1. By the horizontal distance specified in the listing of the electrical boxes;

    2.2. By solid fireblocking in accordance with Section 717.2.1;

    2.3. By protecting both boxes with listed putty pads; or

    2.4. By other listed materials and methods.

    3. Membrane penetrations by electrical boxes of any size or type, which have been listed as part of a wall opening protective material system for use in fire-resistance-rated assemblies and are installed in accordance with the instructions included in the listing.

    4. Membrane penetrations by boxes other than electrical boxes, provided such penetrating items and the annular space between the wall membrane and the box, are protected by an approved membrane penetration firestop system installed as tested in accordance with ASTM E 814 or UL 1479, with a minimum positive pressure differential of 0.01 inch (2.49 Pa) of water, and shall have an F and T rating of not less than the required fire-resistance rating of the wall penetrated and be installed in accordance with their listing.

    5. The annular space created by the penetration of an automatic sprinkler, provided it is covered by a metal escutcheon plate.

solid metal studs would run from floor to top plate without any holes in them allowing communication between wall cavities.


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## chris kennedy (Oct 11, 2013)

1.1. By a horizontal distance of not less than 24 inches (610 mm) where the wall or partition is constructed with individual noncommunicating stud cavities;


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## steveray (Oct 11, 2013)

You might be able to use the insulation if there is any.....

717.2.1 Fireblocking materials.

Fireblocking shall consist of 2-inch (51 mm) nominal lumber or two thicknesses of 1-inch (25 mm) nominal lumber with broken lap joints or one thickness of 0.719-inch (18.3 mm) wood structural panel with joints backed by 0.719-inch (18.3 mm) wood structural panel or one thickness of 0.75-inch (19 mm) particleboard with joints backed by 0.75-inch (19 mm) particleboard. Gypsum board, cement fiber board,     ********batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place shall be permitted as an acceptable fireblock.**********      Batts or blankets of mineral or glass fiber or other approved nonrigid materials shall be permitted for compliance with the 10-foot (3048 mm) horizontal fireblocking

As a fireblock I mean....and meet 1.3


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## mtlogcabin (Oct 11, 2013)

I was taught under the old SBCCI this did not apply to single metal studs. The concern was with wood studs or staggered stud construction


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## steveray (Oct 11, 2013)

Commentary is not much help in this section either.....What about when you drill your horizontal wire holes in the wood studs? Is that "communicating"?


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## Gregg Harris (Oct 11, 2013)

mtlogcabin said:
			
		

> I was taught under the old SBCCI this did not apply to single metal studs. The concern was with wood studs or staggered stud construction


The same verbiage is in at least 4 different codes and I construe it to pertain to both metal and wood studs.


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## chris kennedy (Oct 11, 2013)

There is no IBC definition so I guess we are supposed to know what a 'non communicating stud cavity' is.


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## ICE (Oct 11, 2013)

chris kennedy said:
			
		

> Would the factory punched holes in metal studs allow cavities to 'communicate'?Thanks


I think so with regards to separating outlets.


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## High Desert (Oct 11, 2013)

What I have always thought was the term 'non communicating stud cavity' referenced wood stud construction with wall covering on both sides. There are no openings between each stud bay. Metal studs with the cutouts would not meet that term.


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## chris kennedy (Oct 11, 2013)

ICE said:
			
		

> I think so with regards to separating outlets.





			
				High Desert said:
			
		

> What I have always thought was the term 'non communicating stud cavity' referenced wood stud construction with wall covering on both sides. There are no openings between each stud bay. Metal studs with the cutouts would not meet that term.


I concur, thanks all.


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## north star (Oct 12, 2013)

*~ # ~*

Chris,

"Communicating stud cavities" simply means that one stud cavity will allow oxygen

or a fire event to travel / expand / communicate / propagate to the next stud cavity.

The idea is to [ hopefully ] contain the fire in a single stud cavity; or sealed cavities,

long enough for the emergency response personnel to arrive and address it before

it spreads, and to allow [ more ? ] time for persons to escape if the structure is

occupied.

Offsetting the electrical junction boxes by 24" further reduces the openings in

to the various stud cavities, *"if"* the studs are spaced on 16" centers.

The whole idea is to [ hopefully ] contain a small fire before it becomes a larger

fire........Think "fire control areas" on a much smaller scale.

*~ # ~*


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## Builder Bob (Oct 14, 2013)

UL used to have a great article about outlet boxes and fire rated assemblies.... the code language is a poor attempt to translate what UL or other third party listing agencies are using for approval of outlet boxes in fire rated assemblies.... if interested, here is the latest condensed version of UL rated outlet boxes in fire rated assemblies

http://www.ul.com/global/documents/offerings/perspectives/regulators/technical/Ul_outletboxes.pdf


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