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sempergoofy
Premium
join:2001-07-06
Smyrna, GA

Best (or required) way to seal conduit penetration in drywall

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I posted some months ago about wiring closet location plans. The house renovation is under way, and my conversion of a small broom closet to a wiring closet is under way.

I have two 1.5 inch conduits that come up from the crawl space into the wall of the closet. I offset them (one taller than the other) so that when the network wires turn toward the back wall of the wiring closet, each will have a straight shot. As suggested in the planning phase thread, I put plywood backer board so that I can hang network-related equipment easily.

My question is, what is the best way to seal around the conduit penetrations in the drywall? Intumescent spray foam? Is that a requirement? Plain old drywall mud? Other?

The renovation contractors can foam around the penetration through the floor plate to keep air from leading around the conduit. But what to do to keep air from leading around the cat-6 cables that will be in the conduit? I have access to some intumescent putty pads.
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psiu

join:2004-01-20
Farmington, MI
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Are you having this inspected/done under permit? If so, I would check with your inspector to see if he has any preferences.

I'm honestly not sure as to residential, other than I think in the past using firestopping materials hasn't been required, not sure if it's changing as code updates. Houses are pretty much tinderboxes anyways, really you just want them to slow the flames down long enough for everyone TO RUN LIKE HELL AND GET OUT

If this was in any standard setting I would see at work here, we would use the intumescent caulk to seal the hole around the conduit, then use putty for the wire/conduit. Applying it properly of course.

errrrr, actually rereading your post, the conduits are coming up through the floor, is that a real wall they are in? That floor penetration would be firestopped, depending on if the wall had a fire rating it may or may not be fireproofed. All bets off in residential though.


nunya
LXI 483
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:13

1 recommendation

reply to sempergoofy
Since it's PVC conduit, fire protection is kind of a moot point. I would just use mud or painters caulk.
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lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:2

1 recommendation

reply to sempergoofy
said by sempergoofy:

what is the best way to seal around the conduit penetrations ...

You can use Sugru to make a slightly flexible silicone seal. »sugru.com/


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
reply to sempergoofy
Mesh tape and mud...


whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9
reply to sempergoofy
I assume there is no requirement to fire-stop the conduit (in which case you wouldn't have been able to use PVC conduit). The professional approach around the exterior of the conduit would have been to sleeve the conduit and then fill annular space between the sleeves and the conduits with flexible sealant. The sleeves will protect the drywall from damage when the conduits move. In your case, as others have said, drywall tape and spackle.

For sealing the interior of the conduit, do so only if absolutely necessary. This would be done if the conduits pass from a conditioned space to an unconditioned space (i.e. indoors to outdoors). Otherwise, do not seal. Do NOT use anything other than listed sealant. Intumescent sealants will be a waste of your money, since the PVC conduit will simply melt or burn in a fire. You could use duct putty or a 2-part foam conduit sealantn such as Polywater FST or similar.


sempergoofy
Premium
join:2001-07-06
Smyrna, GA
reply to sempergoofy
Thanks for all the answers, folks.

It had not occurred to me that pvc and fireproof basically negated each other. I am thinking just straight mud and mesh will be the chosen solution. The gap is only 1/4 inch on each side, and the wall is strictly an interior wall.

That sugru stuff looks interesting. Thanks for that tip.
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tschmidt
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join:2000-11-12
Milford, NH
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reply to whizkid3
said by whizkid3:

For sealing the interior of the conduit, do so only if absolutely necessary.

Networks have a tendency to multiple like rabbits. Assume over time you will be adding more drops or using the conduits as wire chases for other things.

If you decide to seal the opening using something that is easy to remove so down the road it will be easy to open them up to pull more wires. With that in mind don't forget to leave a pull string.

/tom
Expand your moderator at work


sempergoofy
Premium
join:2001-07-06
Smyrna, GA
reply to tschmidt

Re: Best (or required) way to seal conduit penetration in drywall

said by tschmidt:

With that in mind don't forget to leave a pull string.

/tom

Great tip!
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nohup rm -fr /&