Ceiling vs. In-Rack for Automated Warehouse?

11/10/2025

In an automated warehouse, is it feasible to replace the in-rack sprinklers with ceiling sprinklers on the upper racking levels?

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9 Comments

Dan Wilder link

11/10/2025 07:10:06 am

I am unaware of the ability to partially sprinkler a racking system, much less what I believe you are alluding to being an ASRS.

You may find a scheme that allows the top level or two to be protected by the overhead system but again, most of those are setup to be independent of each other.

Pete H

11/10/2025 07:32:29 am

Probably not.

Most in-rack sprinklers are listed and selected based on K-Factor and orifice size as well as being listed to provide-in-rack protection.

So you could find a ceiling sprinkler that is listed for in-rack protection as well as ceiling protection, but it likely won't match the type of sprinkler (ESFR, CMSA, CMDA), the orifice size of sprinkler, and/or the K Factor and/or flow rate of the existing protection design, voiding the system if installed without a redesign.

Jesse

11/10/2025 08:10:01 am

Probably not, but it depends on the design scheme you choose.

Chad

11/10/2025 08:11:37 am

No, because then you wouldn’t have sprinklers to protect above/top the racks. (Not just in the rack)

chad

11/10/2025 09:13:10 am

I clearly misread the OP, please ignore my ignorance.

Glenn Berger

11/10/2025 08:14:27 am

A potential does exists. You need to review the applicable storage chapters of NFPA 13 and evaluate. You might find a solution that allows for ceiling only configuration.

Franck

11/10/2025 09:19:56 am

The in-rack sprinklers should strictly follow the requirements from NFPA 13, especially for high rack automated storage where aisles are narrower and height of storage often exceed 25 ft. The re'quirements to keep free the lo,gitudinal flue space is also to be strictly respected, as well as the minimum clearance between the ceiling sprinklers and the top of storage.

As indicated by Dan, you may have some upper levels (depending on the type of sprinkler protection you have selected) that could be adequately covered by the ceiling sprinkler level, but it depends on the design of your system.

Note that for many high storage bay with automated storage systems, the racks are in fact the structure of the building and there may be some confusion between what is rack and what is ceiling in this configuration.
In all case, the ceiling sprinklers should be provided underneath the roof level (at 12 in. max.) and a minimum clearance of 18 in. (36 in. with CMSA and ESFR sprinklers) should be kept between the sprinklers and top of storage.
The ceiling sprinklers may be located (and it is in some way advisable) in the aisles between the racks for a better coverage (when it is feasible with the maximum spacing requirements).

Jack G

11/11/2025 12:19:36 pm

Usually the racks support the roof in an automated warehouse and the floor have to be spot on level. Omitting in rack sprinklers is a definite no in my opinion.

Derrick link

11/11/2025 02:10:01 pm

I attended the SFPE symposium earlier this year on ASRS systems and the speaker (from AutoStore) proved that a ceiling only ESFR system would work for certain ASRS systems. They've done multiple large-scale tests. I can't remember exactly what the design criteria was, but I'm 95% certain that she said it would require 4 hours of demand. There might be a white paper on AutoStore's website or similar that might help.

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Ceiling vs. In-Rack for Automated Warehouse?

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