OK to Acoustically Seal Sprinkler Penetration?

5/23/2025

We are converting a 1930s church to a live music venue. To prevent noise, we are sealing the roof in the attic and insulating the ceiling in the attic.

The fire sprinkler pendants were installed through the existing plaster ceiling with oversized bore holes. Additionally, the pendants have a metal collar with 4 integral slots.

Is it permissible to seal the oversized bore hole?

Is it permissible to seal the upper terminus of the slotted metal collar?

We're not looking to violate code but address the sound needs. Thanks in advance.

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11 Comments

Casey Milhorn

5/23/2025 08:20:07 am

Hard to tell from the picture, but it appears it might be a concealed pendent. If so, you cannot seal on the finished ceiling side where the concealed plate is. Anything that could keep the plate from "falling away" should be avoided. Other types of escutcheons generally are okay to seal around, but for maintenance purposes it would be best to install any sound caulking/materials on the unfinished side of the ceiling and make sure it doesn't come in contact with the concealed plate. Also, if it is a concealed head, you might consider a clean room seal option, if available. They aren't overly expensive and could help cut down some on sound transmission. The seal should be listed with the concealed plate, which should be listed for that specific sprinkler pendent. The entire assembly must be listed.

Glenn Berger

5/23/2025 08:29:33 am

Need to take care to not to damage the operation integrity of the sprinkler.

You might want to look at sprinklers that have the larger cover plates.

Zack Hinson

5/23/2025 08:31:53 am

Concealed sprinklers penetrations are not allowed to be sealed. NFPA 13 2019 16.2.5.4. Also the holes in the top of the concealed pendent are there specifically to get heat to come up into the sprinkler compartment and removing the draft from the heat could remove the listing of that sprinkler.

Jesse

5/23/2025 08:39:39 am

That's a pretty big "no".

Dan Wilder

5/23/2025 08:47:09 am

Yes, No, and with care....

You may fill the cavity around the sprinkler cup and even fill in the oversized hole through ceiling provide that the "mud cup/wrenchable cap" or other means to allow the lower cover plate installation and no materials or debris become lodged within the cup or sprinkler parts. This also assumes you are not in a seismic area where the oversized hole and cover plate is required.

As to the slots in the top, some MFG's have something like this in their installation literature while others are silent on the issue:

"Ensure that the 4 slots in the cup are open and unobstructed
following installation. "

Most times those slots are for an installation socket with notches that align with those slots to allow installation but there is no restriction or requirement as to what covers above that to keep some sort of ability of airflow through those slots (that I have been provided) as we see installations with batt and blown insulation packed around the top of the concealer a lot.

DO NOT USE spray foam, that stuff will expand into the sprinkler cup and require replacement, we see it too often and is an expensive learning lesson.

When in doubt, reach out to the sprinkler manufacturer for written direction for their product and allowed installation conditions. Most sprinklers will have Sprinkler info/MFG information on the deflector of the sprinkler.

Chris

5/23/2025 10:34:38 am

Wild shot in the dark... What if you took a red solo cup, cut it in half and cut the middle out (so if could fit around the pipe), then taped it around the pipe (upside down) on the topside shown in the photo. Then, took expanding foam insulation and encased the cup.

To resolve the issue with having airflow above, maybe put 1-2 straws in the solo cup prior to foaming it, then cut to approximate length after foaming it.

This method would be slightly rigging it, but it would be cheap and fast, and would also solve most of the issues mentioned above. It would not touch the sprinkler and the sprinkler would still be replaceable, it would allow the airflow the manufacturers want to get the heat to activate the sprinkler faster, and it would provide some sort of acoustic sealant to prevent sound from traveling past.

Or just throw some batt insulation around it? (lol)

Adam Jensen

5/23/2025 11:13:59 am

I'm wondering if a dry barrel boot would do the trick (or be allowed)...

https://www.tyco-fire.com/products-and-solutions/sprinklers-nozzles-and-accessories/dry/dsb-2_fis/dsb-2-dry-sprinkler-boot

Thomas Spendiarian RA link

5/26/2025 12:23:20 am

Thanks for all the comments and advise.
The project is in Tucson AZ in seismic zone 2A.
The picture is taken from the attic looking down at the ceiling with the FP pipe and pendant cut thru it. The light showing thru illustrates the open path for sound to come into the attic.
They are concealed type pendants w/ trim plates.
Our problem is that their configuration and the way they were installed creates a hole which is a sound path from the occupied space into the attic. There are about 30 pendants in the ceiling.
My question is: How can these pendants be sealed from the attic side? Is there a Mfg gasket or collar that can be placed above the pendant?
Since we want to avoid creating a mess with expansive foam snt. Can we build up a plaster hood or shield above the sprinkler assembly?
We will contact the designer and ask about clean room seals and dry barrel boots, (which look like they could solve our problem).
Will report back with their feedback.
Thanks in advance for your time and consideration.
TS

Warren

5/28/2025 11:21:02 am

If you are just looking for sound attenuation, wrap the pipe (above the ceiling) with rock wool insulation that is thick enough to cover the annual space, snug it down to the top of the ceiling, then put a hose clamp around the upper portion of the insulation to keep it in place. This will not interfere with the clearance around the sprinkler head or the performance of the sprinkler system.

Joseph Wright

5/28/2025 10:07:30 am

I would recommend using a Tyco Dry pendent boot.

It could be sealed to the ceiling and to the pipe.

Thomas Spendiarian link

6/9/2025 07:48:11 pm

The client has agreed to use the dry pendant boot
and add a layer of plaster placed around the top of the boot in the attic.
This is a bit labor intensive, however the sprinkler pendants have to be R&R'd due to the 3" acoustical insulation we are going to spray on the interior of the ceiling. So since the FP contractor will be working on each pendant anywayt, the addition of a boot is not an excessive cost and the acoustical seal will be much better than an open hole.
Thanks again for all the comments and advise, especially since it has led to a practical solution.
TS

OK to Acoustically Seal Sprinkler Penetration?

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