Fireblock Foam Requirment for Wiring Through Drilled Holes?

Tom PultzNovember 30, 2009

I understand all wire penetrations through top and bottom wall plates must be sealed with fireblock foam or sealant. Correct?

If so, what is the requirement for horizontal runs of wiring, such as through wall studs or floor joists? Does every penetration need to be sealed, or just every xx feet?


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varies from one locale to another.

call your local building inspector/fire marshal, it's not an electrical requirement.

    Bookmark   November 30, 2009 at 6:38PM
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For energy efficiency purposes they should be sealed anyway and I would go ahead and use fireblock foam. It will make a difference and doesn't take that much time.

    Bookmark   December 1, 2009 at 11:21PM
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Ron Natalie

Well except that fireblock foam may or may not meet the local code when a fireblock is required. On the other hand if the holes are through a member that's in the same space, there's nothing to be gained either for fire or energy efficiency stuffing extra stuff in there.

    Bookmark   December 2, 2009 at 8:16AM
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Tom Pultz

The reason I asked about the foam is I saw this orange type foam used on a new house that was being built in our area, so I thought it was probably a requirement. There is probably no energy efficiency to be gained from sealing a penetration in the top plate between 1st and 2nd floors, but for penetrations down into the crawl space I think it would help.

For crawl space penetrations I have tubes of fireblock sealant (red) I was going to use around all the plumbing penetrations.

When the house was constructed all top plate and plumbing penetrations were "sealed" with pieces of fiberglass stuffed up into each hole around the wires or pipes. I don't know if that was required by code back in 1984 or not.

I guess the best thing to do is contact the electrical inspection folks.

    Bookmark   December 2, 2009 at 1:14PM
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This brings a question to mind...

The main power cables coming into our 10 year old house in northern Illinois are fed through metal conduit from the outside (where the meter is located) down to a basement and into the circuit breaker box. The distance is about 6 feet total.

During the winter, cold air comes through the conduit, and along with the cold air there is condensation...enough condensation that there was water dripping in the circuit breaker box. We actually had a breaker trip one time. And the breaker box has developed some rust at the bottom.

As a quick fix I stuffed some insulation into the metal conduit between the incoming power cables.

What should I have done instead?

    Bookmark   December 2, 2009 at 3:39PM
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Seal the top and bottom with duct seal......of course the meter box is "locked" now........

Here is a link that might be useful: Duct seal

    Bookmark   December 2, 2009 at 5:34PM
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Generally ALL fire rated rooms are to be fire rated for a minimum of 1 hour or more depending on your county ordinances.
All penetrations have to be sealed as well. This is where the foam comes in. You stub a wire into that room, and the space around it MUST be filled with fire rated foam.

After that, there is no requirement unless the city adopts there own requirement.

    Bookmark   December 2, 2009 at 8:53PM
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The code requirements for fireblocking can be found in the International Residential Code, which is the model code used for one- and two-family dwelling construction throughout most of the US. The code states the following:
R602.8 Fireblocking required. Fireblocking shall be provided
to cut off all concealed draft openings (both vertical and horizontal) and to form an effective fire barrier between stories, and between a top story and the roof space. Fireblocking shall be provided in wood-frame construction in the following locations.
1. In concealed spaces of stud walls and partitions, including
furred spaces and parallel rows of studs or staggered
studs; as follows:
1.1. Vertically at the ceiling and floor levels.
1.2. Horizontally at intervals not exceeding 10 feet
(3048 mm).
2. At all interconnections between concealed vertical and
horizontal spaces such as occur at soffits, drop ceilings
and cove ceilings.
3. In concealed spaces between stair stringers at the top and
bottom of the run. Enclosed spaces under stairs shall
comply with Section R311.2.2.
4. At openings around vents, pipes, ducts, cables and wires
at ceiling and floor level, with an approved material to
resist the free passage of flame and products of combustion

Products that can be used for fireblocking, as tested and certified by the ICC Evaluation Service, include Hilti CF810 Fireblocking foam, Dow Great Stuff (orange) fireblocking foam, and others. When evaluating a product for this application, look at the label to see if it mentions ICC-ES and fireblocking.

    Bookmark   December 14, 2009 at 7:03PM
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Tom Pultz

Thanks for the info. This agrees with what I have been told. The foam I have is made by DAP. It says on the front "evaluated by the ICC-ES" but it does not say it's certified. Hmmm, guess I will look at the Dow Great Stuff and see what is says on the can.

    Bookmark   December 15, 2009 at 5:00PM
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