How to Address Edge Beam Pocket with ESFRs?

7/21/2026

I am designing a 25.2k ESFR system in warehouse with purlins set on tapered beams with about 8" wide flanges spaced 20' on center. The last beam in the project area runs 1'-5" off the wall creating a small beam pocket along the length of the wall.

Current head spacing is 10'x10', and 18" below ceiling. The sprinklers adjacent to the beam are 3'-10" from centerline, or 5'-3" from the wall. This would require heads within the beam pocket, but the clearance between the wall and beam would obstruct sprinkler discharge.

Are there any special exceptions that would allow heads to be omitted from the pocket?

Or how could I approach this condition differently to meet code?

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10 Comments

Arthur Gould

7/21/2026 08:32:08 am

I am interested in knowing the responses but I would be more concerned with the total 5'-3" off the wall than the pocket.

Chris Nelson

7/21/2026 09:33:35 am

I have experienced this and included ESFR underneath the pocket with shields because thats is what I believe code would require, it was also at the maximum height for ESFR (line 1 for 40' rack 45' ceiling), but I see that this not even half the height of my building so I would be more inclined to not do it. ( PS The contractor didnt like it, shocker)

Jack G

7/21/2026 11:27:13 am

Exceeding 5 foot off the wall is my main concern.
Storage could be stacked against the wall leaving 1-5 obstructed and technically 3 inches not protected.
Any protection in the pocket would at least protect the 3 inches.
Remember the z purlins are on top of the truss beam ( I d call it beam and girder) so the ceiling is the top of the purlins ( could be 8,9, or 12 inches) which places the sprinkler in between the top and bottom of the truss and obstructs flow below the truss / girder.
I would protect below the pocketed truss with shields. The sprinkler head would be at the same height as the one 5-3 off the wall.

Kyle Wilcox

7/23/2026 11:31:25 am

Note that all ceiling-level ESFR sprinklers in a compartment must be 8 feet apart.

This general idea can still work if you stagger the heads on one of the lines to build the required 8-foot separation between all ceiling-level sprinklers (diagonal distances are longer). But if the lines are only ~5 feet apart, I think even the diagonal distance won't be large enough.

danefre

7/21/2026 12:06:07 pm

ESFR is an interesting choice for this building. What are you protecting that needs K25.2 ESFR at 12'-6ish AFF?

Storage will have to cap at 9'-0 with ESFR and there are more effective ways to protect 9'-0 of Group A plastics. CMDA would allow 11'-0 of storage.. higher deflector and 18" clearance to top of storage. The door also looks to be of the overhead type which is a pain with ESFR.

To answer your question the only compliant way is to install a line in the beam pocket and use the 2022edition allowance to use the beam as a baffle and have the lines spaced less than 8'-0 apart.

Colin B

7/21/2026 03:15:06 pm

This is an interesting job for us. The first section of the building is much higher ceiling heights using K25's and the owner wants the same style system in this next smaller storage area so they can have the same level of tenant flexibility as the first 1/3 of the building. That's the main reason for the ESFR K25's. we Explained a CMDA and he would rather stick with what is already installed in the other areas if possible

Dan Wilder

7/21/2026 08:29:43 pm

So...the new NFPA 13 2028 2nd Draft has a new section concerning this setup with a diagram. I can't copy the TerraView info so check it out as to intent.

Currently there is nothing with a similar allowance in the standard.

NFPA Login required
https://submittals.nfpa.org/TerraViewWeb/ViewerPage.jsp?id=13-2025.ditamap&draft=true&toc=false

Corey

7/22/2026 06:58:08 am

Thank you for these comments everyone. One alternative I considered would be to shift the line to 6' off the wall, then shorten head spacing along the line to 8'. This should allow heads to spray under the beam and to the wall, except for the corners where the beam is deepest. However, I'm unsure if i would need to provide an ESFR head in the corners or if NFPA allows for a smaller K-factor head.

Chris Lizakowski

7/22/2026 01:45:46 pm

Correct me if I am wrong but you can shift the one line 1'-0" making it so 5'-6" off the wall is your maximum distance. As long as you don't exceed 110 sq ft.

Kyle Wilcox

7/23/2026 11:03:49 am

Feels like an odd choice to use ESFR sprinklers in such a short building. Max storage height may be 6 or 8 feet?

When I run into this, I usually design my ceiling ESFR sprinklers first completely ignoring these beams, and then I recognize that the beams cause a spray obstruction, and then I add extra ESFR sprinklers below the obstruction. This satisfies our code "verbatim", and makes practical sense: if the fire is on the wall, it will set off the under-beam sprinklers which are directly above the fire and those sprinklers will do most of the work. If the fire is far from the wall, it will not needlessly activate these sprinklers because they're very low.

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How to Address Edge Beam Pocket with ESFRs?

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