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Community and Q&A

Sealing around fire sprinklers in cathedral ceiling

dburgoyne | Posted in Energy Efficiency and Durability on

I have a vaulted, insulated, cathedral ceiling in warm California (zone 3) and code required firesprinklers for my tiny guest house (5 total). My piping and sprinkler heads are installed in the center of my 2×12 bays, which will be filled with R-38 fiberglass batts. I have another R-18 of rigid insulation above the roof sheathing. Once insulation is in place, I will install drywall. The firesprinklers have covers for them (similar to photo) with fusible links that will open in extreme temperatures.

I read the article “Wasting Energy or Catching Fire” which recommends placing sprinklers in interior soffits, or interior walls, but this is not an option for me.

Has anyone had experience or recommendations on how to seal around these sprinkler heads & covers in a cathedral ceiling?

Thanks for any recommendations!

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  1. GBA Editor
    Martin Holladay | | #1

    The best article I have seen on this topic is Abe Kruger's article in Home Energy magazine. Here is the link: Wasting Energy or Catching Fire.

  2. dburgoyne | | #2

    Yes, I read that article and its recommendations to place sprinkler systems in an interior soffit or wall, similar to ductwork recommendations. However, I have very few interior walls, and the piping is already installed in the middle of my rafter bays, so I don't have that option here.

    Any idea how to seal around these pipes or covers without risking the integrity of the cover's ability to drop and engage the fire suppression system in the event of a fire?

  3. BobHr | | #3

    dense pack cellulose comes to mind

  4. kentthompson | | #4

    Hello Dan,

    I have the same question as you, likely at the same stage of construction you were at, past the point of adding a soffit. How did you handle it?

  5. Expert Member
    KOHTA UENO | | #5

    I would assume that any air sealing that "glues in" the drop-away cover will be a no-go. If there's a way to seal around the pipe to the topside of the gypsum board, that might be plausible. But you're still quite likely to run into issues with the fire inspector; Joe wrote about it here:

    BSI-060: Joe South Assemblies

    The sprinkler heads and escutcheon plates need to be airtight where they penetrate the ceiling (Photograph 4). Easy, so just seal them. Not so fast. Were they tested “sealed” or “unsealed?” This matters a great deal to that “fairly complicated and typically stubborn creature.” [fire official] The manufacture of the sprinkler system has to sign off on this. Good luck. Or the “authority having jurisdiction.” Even more luck needed. Or the “architect of record” has to seal the drawing.

    Sealing the sprinkler heads and escutcheon plates is the “right thing to do” but not often possible because they have not been tested in that configuration and an “exception” has to be granted. An even “better” right thing to do would be for the industry to test their stuff in the “right configuration” – the “sealed” configuration.

  6. kentthompson | | #6

    Thanks...I'm afraid I have very little knowledge in how the sprinklers work, which makes me cautious. Apparently there is a moving part to these concealed sprinklers as you mention. I *d0* want them to function as designed if needed.

  7. Expert Member
    BILL WICHERS | | #7

    Any moving assembly should be contained within the sprinkler assembly. You certainly don’t want to fill the sprinkler assembly housing with something like blown insulation though. At best, the insulation might act to delay the operation of the thermal fuse in the sprinkler. At worst, the sprinkler may jam and fail to operate properly.

    I would think you could “box over” the sprinkler with polyiso similar to how recessed lights are done when doing air sealing work. This would leave an air space around the sprinkler assembly which should allow it to function normally.


  8. kentthompson | | #8

    Thanks Bill, that seems like a good solution.

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