ESFR Bottom Chord Rule in NFPA 13 2025 Edition?

3/10/2026

We are working with an insurance agent on replacing an existing warehouse system with ESFR sprinklers; the edition they are applying is NFPA 13 2025.

Previously, in the 2016-2022 editions, there has been a section provided for ESFR obstructions regarding the bottom chords of bar joists or open trusses; however, this doesn't appear to be addressed in the 2025 edition. The insurance agent is suggesting we follow Table 14.10.2.1(a) for the obstruction of the bottom chord of the bar joist, which would require us to install the ESFR pendents up to 4 feet away from the bar joist.

Is this the correct obstruction table to follow, or are we missing a section in the 2025 edition that permits the deflector to be installed a minimum of 6 inches away from the bottom chord, as outlined in the previous editions?

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5 Comments

Sam

3/10/2026 08:09:41 am

The requirements changed to be more generalized in the 2025 edition. Take a look at Section 14.2.10.3.4, specifically note (3):

14.2.10.3.4 Supplemental sprinklers shall not be required below obstructions when the obstruction or occupancy is in accordance with one of the following:
(3) The obstruction is 6 in. (150 mm) or less in width and is located a minimum of 6 in. (150 mm) horizontally from the sprinkler.

Michael

3/11/2026 10:47:00 am

That's actually beneficial since the original rule that was specific to bottom chords mentioned "ESFR sprinklers shall be positioned a minimum of 1 ft horizontally from the nearest edge to the bottom
chord of a bar joist or open truss where the bottom chord does
not exceed 1 ft in width."

Allowing us to get closer to the chord if it's less than 6" in width should be beneficial to ESFR spacing which is always a chore.

3/10/2026 09:09:26 am

14.2.10.3 Obstructions that Prevent Sprinkler Discharge from Reaching Hazard. (See A.‍9.5.5.2.)

14.2.10.3.4 Supplemental sprinklers shall not be required below obstructions when the obstruction or occupancy is in accordance with one of the following:
(1)The location of the obstruction relative to the ceiling sprinklers complies with Table 14.2.10.2.1(a) or Table 14.2.10.2.1(b).

(2)The obstruction is 11⁄2 in. (38 mm) or less in width and is located a minimum of 12 in. (300 mm) below the elevation of the sprinkler deflector.

(3)The obstruction is 6 in. (150 mm) or less in width and is located a minimum of 6 in. (150 mm) horizontally from the sprinkler.

(4)The obstruction is 24 in. (600 mm) or less in width and is located a minimum of 12 in. (300 mm) horizontally from the sprinkler.

(5)The obstruction is 4 in. (100 mm) or less in width, and is located entirely below the sprinkler pipe connected to the ceiling sprinkler, and the ceiling sprinkler is upright.

(6)The occupancy is protected in accordance with 14.2.6, and obstructions comply with 9.5.5.3.

Mark Harris

3/10/2026 09:54:21 am

I recall in the 90's having to rework some installs that had the pendent ESFR too close to bar joists. At the time I think FM had a checklist that addressed their requirements. Also remember Real Estate firms paying for inspections and sprinkler location related to joist obstructions was one of the specific requests.

Has anybody looked at the ESFR manufacturer data sheets? if they have more restrictive spacing requirements than NFPA the data sheet would apply.

At least in the past this was a big enough issue that the large warehouse builders worked with the sprinkler contractors on their structural steel layouts to be more ESFR layout friendly.

Jack G

3/10/2026 07:09:59 pm

I follow the ESFR FM guidelines. FM wrote the book and did all the testing…. NFPA just follows. FM has great issustratiins for most scenarios with explanation.
A Chubb insurance guru thought me that.

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ESFR Bottom Chord Rule in NFPA 13 2025 Edition?

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