Are Sprinklers Req'd Below Wood Slat Ceiling?

9/15/2023

Are pendent sprinklers required below a decorative wood slat feature along the ceiling?

Wood slats vary in height from 4" to 12" but is suspended at ceiling height (9'-0").

The area above the slats is concealed space and requires uprights. The total area percentage of slats is 42% below the concealed space.

Thanks in advance.

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15 Comments

Pete H

9/15/2023 06:46:17 am

Can you protect this room with sidewalls?

Specifically with deflectors 12" below the ceiling?

Pete H

9/15/2023 06:48:27 am

Also giving it an extra few seconds, it doesn't look like 9'-0" is your ceiling height the slats are suspended from in that pic, it looks like 9'-0" is the height of the ceiling under the 12" soffit and the slats are suspended from the 10'-0" ceiling above that. Is this the case?

Either way, I'd still try to work with sidewalls 12 inches below the ceiling height.

Pete H

9/15/2023 06:57:41 am

And finally to actually answer the question, yes you need to protect the floor under the wood slats,. If the above area is a combustible concealed space, you need to have protection at both levels.

You will only need to calculate protection at one level. But it must be present at both.

James Evans

9/15/2023 09:11:59 am

You could not use sidewalls at 12" below the cieling because the soffit and the slats end at 12". This means your sidewall would need to be more than 12" if used on that wall with the soffit. Unless you sprayed from an adjacent wall opposite the slats. In situations like this we usually use a pend sprinkler on a bell reducer with no skirt or escutcheon and make the deflector about an 1" below the slats. the pipe can be painted to match the color.

DAVE

9/15/2023 10:40:28 am

Unfortunately, sidewalls can only be installed below smooth, horizontal, or sloped flat ceilings (LH) or smooth, flat ceiling where specifically listed.

Glenn Berger

9/15/2023 08:14:21 am

Your question states that the space above the slats is "concealed." Sprinklers would be required to protect the space below the decorative ceiling feature.

Anthony

9/15/2023 08:27:48 am

Yes, sprinklers are required in the habitable space if they're required in the combustible concealed space above..

Maybe drop a pendent sprinkler next to the 12'' slat, shave that slat to 11'' so the sprinkler can operate properly. Paint the pipe and get a custom color exposed pendant.

I'm referencing the fact that sprinkler deflectors must be within 12'' of the ceiling.

Note also, I think your spacing will be 168sqft (130?) not 225sqft due to the fact the wood slats create a combustible ceiling.

Best of luck with the challenging design.

Juan l

9/15/2023 08:28:28 am

Use EC Tyco side wall heads, and you don’t need any uprights.

Andrew MacLean

3/24/2025 12:42:41 pm

Nothing about this seems like the Smooth Level ceiling their listing calls for.

Franck

9/15/2023 08:54:56 am

You have some requirements in NFPA 13 for open-grid ceilings. Which is what you have with your configuration.

9.2.16 Open-Grid Ceilings.
Sprinklers shall not be required below open grid ceiling installations complying with 9.3.10.

9.3.10 * Open-Grid Ceilings.
Open-grid ceilings shall only be installed beneath sprinklers where one of the following is met:

(1) Open-grid ceilings in which the openings are 1∕ 4 in. (6 mm) or larger in the least dimension, where the thickness or depth of the material does not exceed the least dimension of the opening, and where such openings constitute 70 percent of the area of the ceiling material. The spacing of the sprinklers over the open-grid ceiling shall then comply with the following:

(a) In light hazard occupancies where sprinkler spacing (either spray or old-style sprinklers) is less than 10 ft × 10 ft (3 m × 3 m), a minimum clearance of at least 18 in. (450 mm) shall be provided between the sprinkler deflectors and the upper surface of the open-grid ceiling. Where spacing is greater than 10 ft × 10 ft (3 m × 3 m) but less than 10 ft × 12 ft (3 m × 3.7 m), a clearance of at least 24 in. (600 mm) shall be provided from spray sprinklers and at least 36 in. (900 mm) from old-style sprinklers. Where spacing is greater than 10 ft × 12 ft (3 m × 3.7 m), a clearance of at least 48 in. (1.2 m) shall be provided.

(b) In ordinary hazard occupancies, open-grid ceilings shall be permitted to be installed beneath spray sprinklers only. Where sprinkler spacing is less than 10 ft × 10 ft (3 m × 3 m), a minimum clearance of at least 24 in. (600 mm) shall be provided between the sprinkler deflectors and the upper surface of the open-grid ceiling. Where spacing is greater than 10 ft × 10 ft (3 m × 3 m), a clearance of at least 36 in. (900 m) shall be provided.

(2) Other types of open-grid ceilings shall be permitted to be installed beneath sprinklers where they are listed for such service and are installed in accordance with instructions contained in each package of ceiling material.

A.9.3.10
The installation of open-grid egg crate, louver, or honeycomb ceilings beneath sprinklers restricts the sideways travel of the sprinkler discharge and can change the character of discharge.

This means that if your installation does not meet the requirements of 9.3.10, you need sprinklers.

Note that if you can omit sprinklers below the structure, then the sprinkler protection at the ceiling level should be designed for the occupancy in the room (not only for a concealed space area).

Dan Wilder

9/15/2023 09:16:40 am

Are these slats attached directly to the ceiling?

-Yes to protection below the slats via pendents either within or between the slats. You’ll have to check horizontal obstruction clearances for wherever the deflector/bottom of slats distances are.

If these slats sit below the ceiling, depending on that distance, you may need additional sprinklers above the slats (watch suspended obstruction rules) and due to the less than 70% open, protection below the slats

The area above the ceiling needs to follow the requirements for combustible or noncombustible concealed space requirements.

I’m not a fan of sidewalls for ceilings with this much channeling potential and obstruction to spray patterns parallel to the wall (if looking beyond the smooth flat ceiling requirements)

SCHULMAN

9/15/2023 09:23:24 am

These guys are right, yes, you need sprinklers ... probably sidewalls are best but if it's an architectural issue and someone doesn't want sidewalls .. (I have done lots of crazy ceilings for lots of crazy bosses) ... you can put the sprinklers on pendants between some of the slats (making sure you have the floor coverage required at a minimum) and drop them to just "in-line" with the bottom edge of the wood slats which will help "hide them" - heck, I've even had contractors custom paint the piping and escutcheons etc... and as always - TALK TO YOUR AHJ.

Dave L.

9/15/2023 10:57:26 am

This one hits home. I've encountered a lot of variations on this as my architect friends keep coming up with new ideas. In some scenarios with multiple trendy baffles suspended from a ceiling above, I try to work with the architect to get them to suspend the slats low enough from the ceiling so they do not affect the spray pattern. I just had some projects that had areas similar to the posed question where they are attached directly to the ceiling. Sidewall sprinklers cannot be used below this type of ceiling (8.4.2 '16 ed; 10.3.2 '19 ed.). I was able to talk the architect into allowing me to extend 1” drops to pendent sprinklers centered between two slats, deflector just below the slats, let the architect choose the sprinkler color, and paint-out the pipe. Sprinkie made a mock-up to show the architect. They chose painting the pipe over that over a long escutcheon (that us old timers have a nickname for). In my case, the deflector of the pendent was able to be at 12” below the ceiling, although I suppose this could be treated as obstructed construction and go up to 22”. The space above the ceiling is its own situation.

9/20/2023 03:23:39 pm

If the slat has no backer then we would follow open grid ceilings and protect with uprights, spacing dependent on deflector distance above top of baffle. If the slat has a finished backer and all ceilings return to the deck we would place the pendent at 12" below the finished backer with no uprights above 225sf spacing. If the slat has a backer but all ceilings do not return to deck we would protect above and below 225sf spacing.

Justin Smith

5/30/2025 08:05:11 am

I've recently run into a situation like this as well, Just wondering if you have to provide sprinkler coverage above and below would you need a water shield to protect the sprinkler head below? It is my understanding that you would.

Are Sprinklers Req'd Below Wood Slat Ceiling?

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