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#84614 - 03/31/03 08:22 PM Fireblocks - drilling holes
ThinkGood Offline

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
A neighbor is having a "gut job" done on his house--now it is down to the bare wood.

The contractor is putting in fireblocks in between the existing studs (this is an old house, no fireblocks were used originally) before the electrician comes in to completely rewire the house, before the sheetrock goes up. (By fireblocks, I mean 2x4s that are cut to fit in horizontally between the studs.)

I got to thinking (yeah, I know, thinking can be dangerous)...if the electrician is possibly going to need to drill through fireblocks, doesn't that open a whole can of worms, in that that the fireblock is then compromised? Does the electrician need to seal around the cable to completely fill the hole, or does this apply only to commercial dwellings?

I can't imagine that the guy is going to have to seal every hole drilled vertically yet I find it ironic that an area with electric cable would have holes in the fireblock...

2014 / 2011 NEC & Related Books and Study Guides
#84615 - 03/31/03 08:35 PM Re: Fireblocks - drilling holes
Bill Addiss Offline

Registered: 10/07/00
Posts: 4196
Loc: NY, USA

This Blocking is commonly used in the Interior walls. We call them "Cats" (Anyone know why?)

I've never heard of holes through them being an issue but am curious about the requirements for these. I did find something in the NYS Resi Code (which is a modified IRC) Electrical Section, but not sure what it means:

E3302.3 Penetration of firestops and draftstops. Penetrations through fire blocking and draftstopping shall be protected in an approved manner to maintain the integrity of the element penetrated.


[This message has been edited by Bill Addiss (edited 03-31-2003).]

#84616 - 03/31/03 09:21 PM Re: Fireblocks - drilling holes
CTwireman Offline

Registered: 02/07/02
Posts: 839
Loc: Connecticut, USA
Here in Connecticut we are required to fill these holes with fire stopping (retarding?) compound.

#84617 - 03/31/03 11:50 PM Re: Fireblocks - drilling holes
nesparky Offline

Registered: 06/21/01
Posts: 650
Loc: omaha,ne
see 300.21
A lot of places say if you drill it you seal it.

#84618 - 04/01/03 12:24 AM Re: Fireblocks - drilling holes
lwinter31 Offline

Registered: 11/23/02
Posts: 41
Loc: Texas
This is really not a big issue here. 2 to 4 vertical pulls per room max to seal. The just of cable in walls is pulled horizontally in residential installs.

Bill ? - CATS=(Cuss At Them Suckers)?

#84619 - 04/01/03 04:08 AM Re: Fireblocks - drilling holes
Redsy Offline

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
We are regularly required to "fire caulk" penetrations that separate 2 floors. The caulk can cost $10-15 per tube.

#84620 - 04/01/03 05:17 AM Re: Fireblocks - drilling holes
ThinkGood Offline

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Thanks for the quick response.

nesparky: 300.21 -- That's the one I remembered but couldn't find.

I've never noticed any kind of caulking, etc. in the photos here (and elsewhere) that show Romex through holes. (OK, many of the photos here are posted to show violations anyhow :eek nor have I seen it in the few newly-built houses I have seen.

I did find the caulking online--one site had it for about $9 per tube.

Interestingly enough, I found some articles (via Google searches) that stated that fiberglass insulation, when the barrier material is covered, is better than wooden fireblocks.

lwinter31: Your explanation of "cats" sounds very plausible

As usual, you folks gave great information.

#84621 - 04/01/03 06:07 AM Re: Fireblocks - drilling holes
Electricmanscott Offline

Registered: 01/12/02
Posts: 1478
Loc: Holden, MA USA
Here in MA I beleive you are required to seal penetrations between floors. Not 100% sure though, general contratctors usually do this.

#84622 - 04/01/03 10:51 AM Re: Fireblocks - drilling holes
pwood Offline

Registered: 02/04/03
Posts: 64
Loc: castella,calif usa
fireblocking required in walls at ten foot intervals.fireblocks required at blocks required at stair stringers.a dab of fire caulking at the penetrations is sufficient if the product is listed that way.if the fireblocks are not code required no protection is required.

#84623 - 04/01/03 02:46 PM Re: Fireblocks - drilling holes
ken m Offline

Registered: 08/14/01
Posts: 61
Loc: south carolina
here in s.c. the blocks are called perlins or perliners (sp) they are only required in interior walls that exceed 8' in height. the requirements are to use the mortar or caulk in the top and bottom plate not the perlin and of course that depends in which county the job is located. ken m

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