When Does a Soffit Require a Sprinkler Inside?

3/13/2025

When dealing with combustible soffits, what are the conditions where a soffit is big enough to warrant a sprinkler inside?

In our case, we have wood constructed soffits with sprinkler protection below and adjacent to the soffit.

Thanks in advance.

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7 Comments

Pete H

3/13/2025 07:40:15 am

This is talking about exterior soffits:

From NFPA 13 (2016 Edition)

8.15.1.2.18.1 Sprinklers shall be permitted to be omitted from within combustible soffits, eaves, overhangs, and decorative frame elements that are constructed in accordance with 8.15.1.2.18.2 through 8.15.1.2.18.5

8.15.1.2.18.2 Combustible soffits, eaves, overhangs, and decorative frame elements shall not exceed 4'-0" in width

8.15.1.2.18.3 Combustible soffits, eaves, overhangs, and decorative frame elements shall be draftstopped, with a material equivalent to that of the soffit, into volumes not exceeding 160 cubic feet.

8.15.1.2.18.4 Combustible soffits, eaves, overhangs, and decorative frame elements shall be separated from the interior of the building by walls or roofs of noncombustible or limited combustible construction

8.15.1.2.18.5 Combustible soffits, eaves, overhangs and decorative frame elements shall have no openings or unprotected penetrations directly into the building

---------------------------

I'm guessing given the level of protection you have that this is an interior soffit, so I'd view it as a combustible concealed space. So:

8.15.1.1 Concealed Spaces requiring sprinkler protection. Concealed spaces of exposed combustible construction shall be protected by sprinklers except in concealed spaces where sprinklers are not required to be installed by 8.15.1.2.1 through 8.15.1.2.18 and 8.15.6

8.15.1.2.3 Concealed spaces formed by studs or joists with less than 6 in. between the inside or near edges of the studs or joists shall not require sprinkler protection.

8.15.1.2.7 Concealed spaces filled with noncombustible insulation shall not require sprinkler protection.

8.15.1.2.9 Concealed spaces over isolated small compartments not exceeding 55 square feet in area shall not require sprinkler protection.

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Those are the relevant exemptions I can see. Maybe other people see or know better ones.

Glenn Berger

3/13/2025 08:10:56 am

Need more information to provide guidance.

Is this soffit an exterior soffit or an interior soffit?

What is the building construction?

What is the purpose of the soffit? Decorative? Anything being concealed on the interior of the enclosure?

Ricardo Gonzales Jr

3/13/2025 08:31:22 am

An added question is: Is the interior of the soffit accessible? Like some hard ceiling rooms with 5' of space between the ceiling and deck, the space is not accessible therefore not required to be sprinklered. If you can't access it, why install it?

Wes

3/13/2025 08:37:21 am

That’s not necessarily true. If this is an NFPA 13 system and the concealed space is combustible, then it would require sprinkler protection (unless it meets one of the listed exception scenarios).

If this is an NFPA 13R or NFPA 13D project, then yes a concealed space generally wouldn’t require sprinkler protection even if it’s combustible.

Jesse

3/13/2025 08:34:08 am

To add to Ricardo and Glenn's questions, is this a full NFPA 13 system or 13R / 13D?

Dave L.

3/13/2025 11:03:03 am

I assume this is an NFPA 13 application, and in the 2025 edition, 9.2.1.11 offers a way out: "Concealed spaces created by soffits of combustible construction below noncombustible or limited combustible ceilings separated into volumes each not exceeding 160 ft3 (4.5 m3) by noncombustible or limited combustible materials shall not require sprinkler protection."
(And some enhanced content in the NFPALink version.)

And there is a corresponding Annex illustration accompanied by the text, "Sprinklers are allowed to be omitted from horizontal chases and soffits that have noncombustible or limited combustible finishes that can contain mechanical and or plumbing equipment, ductwork, or electrical components. The 160 ft3 (4.5 m3) limitation is intended to limit the movement of fire within the chase or soffit. It is not the intent of this volume limitation to require dampers or other mechanical separations within ductwork, or other equipment that are not otherwise required. See Figure A.‍9.2.1.11."

If the ceiling under which the soffit is constructed has GWB to the wall, this seems to finally address this common predicament.

Jack G

3/13/2025 05:47:29 pm

I think what Ricardo was meaning is that if there are concealed combustibles in a blind space ( with no access ) and fits the NFPA 13 definitions then sprinklers would not be required but the space below it the minimum design area must be increased to 3000 ft2.
( like a new drop ceiling below a sheet rocked off concealed space )

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When Does a Soffit Require a Sprinkler Inside?

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