# semi recessed FE cabinets membrane penetration in fire rated walls



## syarn (Feb 18, 2011)

3 story; IIB; NFPA13R; 68000sf apartment building (R2); IBC 2006;

the corridor walls & apartment walls are fire rated.

can semi-recessed fire extinguisher cabinets be installed into the rated hallway walls as it would be a membrane penetration of 25"H x 10-1/2"W x 4" deep in U465 walls with 6" metal studs?

the larsen brand cabinet also offers a "flame-shield" fire-rated cabinet option in semi-recessed....


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## steveray (Feb 18, 2011)

oversize the recess and drywall it like the rest of the wall? must be cheaper than a "rated" cabinet.....


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## FyrBldgGuy (Feb 18, 2011)

I agree, just watch for offsets for items inside the wall or opposite side.  May need to use a fill material to get full fire rating.


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## syarn (Feb 18, 2011)

SR & FBG

thx u.

a U465 wall requires a min. wall thickness of 4-7/8" so the recess makes the wall 3-1/4" thick.....isn't that too small?

also why does the code restrict smaller outlet boxes to 100 sq inches per 100 sq feet.....???


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## permitguy (Feb 18, 2011)

The rated cabinets are intended for that very situation.  If you could maintain the rating without them, that's great.  I think it would be difficult, as you've already pointed out.  You'll also want to make sure they don't encroach on the minimum corridor width if you're already close.


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## mark handler (Feb 18, 2011)

*Wrap with gyp. bd.*


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## steveray (Feb 18, 2011)

Sorry!...Missed the 465....most of the ones I see can do it in 2-1/2"....in addition to corridor width, watch the horizontal projections more than 4" of 1003.3.3...been seeing this alot with electric heaters in vertical exit enclosures


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## syarn (Feb 18, 2011)

BCF thanks.

hmm...still struggling to understand the "code" logic....if the recess is NOT U465 due to depth;  than how do I prove that the GWB wrapped recess maintains the 1 hour rating?


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## JBI (Feb 18, 2011)

syarn, If you are the DP on the project it is up to you to provide a code compliant and/or engineered design. If there is any engineering behind the suggestion above to wrap it in GWB, that may be the solution. I can say pretty safely that there is engineering and testing, listing and labeling of the upgraded box. Just make sure it is listed for use in that application.

Part of the limit on smaller electrical boxes is minimizing the risk of unprotected membrane penetrations. Properly protected penetrations shouldn't be a problem.

It's all about maintaining the integrity of the assembly.


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## north star (Feb 18, 2011)

** * * **

syarn,



Like JBI stated, ..."if" you are the DP, ...instead of using gyp. board,

why not use the provisions of Section 104.11 - Alternative

materials, design and methods of construction and equipment [ from

the IBC ] using a thin sheet of metal, say stainless steel or similar,

could be fabricated / installed instead of the thicker gyp. board.

Then the BO would need to approve of this alternative design, and

" Voila! "



** * * **


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## mtlogcabin (Feb 18, 2011)

703.2 Fire-resistance ratings.

The fire-resistance rating of building elements, components or assemblies shall be determined in accordance with the test procedures set forth in ASTM E 119 or UL 263 or in accordance with Section 703.3. Where materials, systems or devices that have not been tested as part of a fire-resistance-rated assembly are incorporated into the building element, component or assembly, sufficient data shall be made available to the building official to show that the required fire-resistance rating is not reduced. Materials and methods of construction used to protect joints and penetrations in fire-resistance-rated building elements, components or assemblies shall not reduce the required fire-resistance rating .

Since item #3 the insulation is optional I would assume no time was given for that product so the recessed fire cabinet did not negatively effect that portion of the assembly. Therefore wrapping the cabinet with gypsum board and fire caulking of the joints should maintain the same level of protection. The depth you are concerned with is the minimum demension stud size before the wall would fail not a required minimum air space or insulation thickness.  JMHO


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## High Desert (Feb 18, 2011)

1-hour? can't you go down to 1/2 hour rating in the corridors per Table 1018.1?


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## peach (Feb 20, 2011)

In an R-2 occupancy I think you could argue that permanently mounted FE's in each unit will provide equivalent protection.  They will certainly be within 75' travel distance of everybody in the building.  The fires are not going to happen in the corridor (usually).. several jurisdictions take out FE provisions because the FD doesn't want (necessarily) non fire professionals attempting to be heros...  the fire fighters want the occupants out of the building rather than interfering.


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## Examiner (Feb 21, 2011)

Use the fire rated cabinets.  Lining the opening with gyp does not work, it is not a tested assembly.  You would have to use a wall system that is rated to frame the opening.  I have done this in metal stud walls where we did not want the back side of the wall to have a bump out.   Prior to rated cabinets we used 1 5/8" studs with gyp on each face at the cabinet.  You can get a 1 5/8" stud wall in an hour rating.  Of course the other ajacent studs were more than 1 5/8" to keep the gyp faces aligned.


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## syarn (Feb 21, 2011)

wow thanks for the additional feedback...

high desert

yes the corridor walls could be 0.5 hours HOWEVER some of these walls also "double dip" as the fire partiton for the sleeping units (apartments) and with a NFPA13R system those walls need to still be 1 hour...

north star & mt log cabin those are the kind of tips I was fishing for....we do have a 1995 warnock hersey test report for the proposed brand cabinet:

https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B8MIb4l-3dteZjliYjFhYzktZTQ2My00N2Y5LTg1YzEtY2ZjYzJhZDkwN2Q4&hl=en

not sure how it ties into 2006 IBC though....


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## yuanyelss (Feb 22, 2011)

If you could maintain the rating without them, that's great. I think it would be difficult, as you've already pointed out...


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## JBI (Feb 23, 2011)

syarn - Have you called Warnock Hersey to see if their testing is still valid?


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## syarn (Feb 26, 2011)

no

did call larsen's;  maker of the rated cabinet.

larsen's said this test is their latest version.

section 712 of IBC 2006 speaks to membrane penetrations and cites astm e 814-02....

the warnock hersey test from larsen's had astem e 814-83....so not keeping up to date seems to be an issue in complying with IBC 2006 code...


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