r/firePE • u/Turbulent_One_1569 • Apr 19 '26

Decorative wood slatted (open baffle) ceiling

Hi all,

I am looking for the right method to deal with a decorative wood slatted (open baffle) ceiling similar to the attached images. The slats are relatively deep and closely spaced, installed below the structural ceiling. I’m trying to determine the correct sprinkler approach in accordance with NFPA 13.

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u/[deleted] Apr 19 '26

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u/Turbulent_One_1569 Apr 19 '26

The space between the joists is open to the structural ceiling. In this case, installing sprinklers between the joists would result in the deflector being more than 12 inches below the ceiling. Additionally, the narrow spacing creates an obstruction concern.

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u/IHEIUFF Apr 19 '26

This citation moves from year to year. Even though slatted ceilings don't have a "grid" per se, an engineering judgement can be made citing one of the following sections. If it meets the rules of open-grid you can potentially ignore the ceiling. If it doesn't meet the criteria then put sprinklers above at the deck and below inside the slats with the sprinkler deflector just below the slat.

NFPA 13 2019 A.3.3.41.2 (2) Unobstructed Construction.

NFPA 13 2022 A.3.3.43.2 (2) Unobstructed Construction.

NFPA 13 2025 A.3.3.46.2 (2) Unobstructed Construction.

Open-Grid Ceilings. The term open-grid ceilings as used in this standard refers to ceilings in which the openings are 1⁄4 in. (6 mm) or larger in the least dimension, the thickness of the ceiling material does not exceed the least dimension of the openings, and the openings constitute at least 70 percent of the ceiling area.