What Opening-Percentage to Omit Sprinklers?

2/9/2024

Is there a threshold of percentage-opening that would allow sprinklers to be omitted below a grill or something similar - like a metal grated catwalk?

Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

7 Comments

Dan Wilder

2/9/2024 06:38:17 am

13-19' - 9.3.10 allows omission of sprinklers below ceilings where the opening is at least 1/4" wide, the depth does not exceed the width of the open space, and the overall opening is at least 70% and there are minimum clearances from the ceiling to the sprinklers above based on sprinkler spacing.

9.5.5.3.1.1 is specific to the terminology of "metal grated catwalk" or in NFPA, "Open grate flooring" where sprinklers are required below without regard to total opening if the grating is over 48" wide.

So, to answer the question as you've asked, there is no percentage allowance, the only way to not provide sprinklers beneath is if it's less than 4' wide.

Anthony

2/9/2024 08:47:20 am

As Dan correctly state if its over 48'' wide you need to have sprinklers protection under any metal grate.

I'd add in the case of mezzanines and industrial platforms that workstations often accumulate non perforated partitions over time. Cardboard, new equipment and those ergonomic standing pads show up fast and change the nature of the hazard. Also, any grating that's 'definitely not for' used for storage will and you get a situation where you have a non-permeable barrier causing an obstruction. So, I think cases like those are where the requirement comes from. -- Once a grate always a floor.

Dave

2/9/2024 10:21:49 am

I agree. I've also seen an informal NFSA interpretation stating the same, for reasoning including what Anthony states. Unfortunately, a grated walkway does not equal an eggcrate ceiling.

Jesse

2/9/2024 08:41:42 am

Agree with Dan's response. The percentage of opening you referred to originally deals with things like slatted ceilings and such.

Jack G

2/9/2024 09:39:16 am

I’m with Anthony.
Once a great—- always a floor, or repair pad near equipment close to great— re baggage terminal grates at airports.

Casey Milhorn

2/9/2024 06:39:48 pm

NFPA has a research foundation that did some recent testing on grated mezzanines and walkways. Very interesting findings and the affect on distribution and overall wetting was fun to see. If you have an AHJ open to making an independent ruling based on this research, you might look this research paper up, but as others stated NFPA 13 is very clear on needing protection above and below when over 48" in width.

Jim

2/14/2024 11:46:52 am

Do you have a link?

Did the tests indicate any thing different- OR are sprinklers below still needed?
------------------------------------------------------------------------------
Short sad story:
New OSHPD inspector at a hospital in Ca remembered the 4 foot wide rule:
But the 5 foot wide ducts were above a hanging tile ceiling below a a concrete floor in the basement of hospital, all non combustible.
So the pipe was up there, but that concealed space was NOT fire sprinkled, nor required to be.
Under those ducts only about 6 inches to the tile.
Yet the architect said Don't Argue, just install a few extra sprinklers.

Leave a Reply.

Home
Our Cause

The Blog
The Forum

PE Exam Prep
The Toolkit
MeyerFire University

Pricing
Login
Support
Contact Us

MeyerFire.com is a startup community built to help fire protection professionals shine.
Our goal is to improve fire protection practices worldwide. We promote the industry by creating helpful tools and resources, and by bringing together industry professionals to share their expertise.

MeyerFire, LLC is a NICET Recognized Training Provider and International Code Council Preferred Education Provider.
All text, images, and media Copyright © 2016-2025 MeyerFire, LLC

We respect your privacy and personal data. See our Privacy Policy and Terms of Service. The views, opinions, and information found on this site represent solely the author and do not represent the opinions of any other party, nor does the presented material assume responsibility for its use. Fire protection and life safety systems constitute a critical component for public health and safety and you should consult with a licensed professional for proper design and code adherence.

Discussions are solely for the purpose of peer review and the exchange of ideas. All comments are reviewed. Comments which do not contribute, are not relevant, are spam, or are disrespectful in nature may be removed. Information presented and opinions expressed should not be relied upon as a replacement for consulting services. Some (not all) outbound links on this website, such as Amazon links, are affiliate-based where we receive a small commission for orders placed elsewhere.

What Opening-Percentage to Omit Sprinklers?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES