Is Horizontal Screen an Obstruction to Sprinklers?

5/2/2022

I have a laboratory space which original had an open ceiling. The renovated space plans to provide a screen, similar to a window insect screen across the open ceiling, which will contain lizards which they are working with.

Is this screen considered an obstruction to the sprinklers above?

The screen would be located approximately 3-feet below the main ceiling at 8'-0" above the floor. Although water would pass through, it seems that it would significantly disrupt the distribution pattern from the sprinklers.

This also does not seem to meet the requirements for an open-grid ceiling. Thanks in advance.

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

8 Comments

Alex

5/2/2022 07:48:23 am

Hi,

This is a good question. I'm sure we will see differing views on this issue in regards to open ceilings versus other horizontal obstructions. Hopefully today, someone can cite a code section that puts the issue to rest!

On one hand, you have NFPA 13 (2022) 9.5.5.3 that states that horizontal obstructions that interrupt water discharge shall comply with 9.5.5.3 and the following subsections.

9.5.5.3.1 states that any obstruction over 4 feet require sprinklers installed beneath.

The annex material states that for slat decks, walkways, or open grating, the use of opening or enlarging the openings are not a substitute for automatic sprinklers. If you go this approach, I would say you require sprinklers beneath your screen no matter your percent open.

On the other hand, the code doesn't call out this specific scenario. Nor will it ever (there are far too many scenarios out there)! Think of providing a screen above a storage compartment within an apartment complex. The screen is installed to prevent storage being stacked too high, thus obstructing sprinkler discharge. But then do you need to install sprinklers beneath the screen? I would say no!

So if you are looking at it this way, I would say treat it like an open ceiling. NFPA 13 (2013) 8.15.14 states to have the screen 70 percent open. Personally, this is how I would prevent sprinklers beneath.

In the end you state that you do not fall under the requirements to be 70% open. Therefore, I would say you do need to install sprinklers beneath the screen.

Thanks,
Alex

Jesse

5/2/2022 08:13:48 am

This is a tough one. The screen will disrupt development of the spray pattern. However, sprinklers underneath the screen probably won't collect enough heat to activate.

I think it does indeed pose an obstruction. I would recommend protecting using either horizontal sidewalls with a heat collector (depending on room size), or regular pendents with heat shields.

5/2/2022 09:54:43 am

No disrespect intended, but "heat collectors" are proven not to work, and are now specifically prohibited in NFPA #13: "Heat collectors shall not be used as a means to assist the activation of a sprinkler. (See also Annex commentary.) Furthermore, sidewall sprinklers shall only be installed beneath smooth, flat ceilings.

5/2/2022 08:23:36 am

I would send an RFI inquiring about how open the screen is. If it's 70% open or more (you can figure this out by doing some simple math that I would recommend showing on your drawing), then I would follow NFPA 13, 2016 8.15.14 for Open-Grid Ceilings. If the screen is not 70% open I would put the decision in the A/E teams hands regarding changing the screen to a screen that is 70% open or adding an intermediate sprinkler with a water shield below the screen to provide above and below protection. I don't think you're going to find this specific situation in NFPA 13, but an Open-Grid ceiling is probably the most similar concept to what you are describing.

Dan Wilder

5/2/2022 08:24:20 am

What's the material? Anything not metal will likely burn away near the fire location anyway. If it is metal, there may be a stronger point for a water shield and sprinklers beneath.

Are they putting any additional "plants" above (Live or dead)? At best (or worst depending on how you look at it), this looks more like a Rain Forest Café to a point but if this is occurring, those locations of "plants" may be your best bet for a lower sprinkler location with a water shield.

Open-grid ceilings have a specific minimum opening, typically 1/4", and have the ability to prevent the sprinkler pattern from developing horizontally. Being 36" below, you could make an argument for a smaller spacing layout to alleviate the spray pattern disruption. An example would be an F1FR56 sprays about 4.5' horizontally at the 3' mark (at 7 PSI) so an 8x8 sprinkler spacing removes the gaps potentially created by the screen. An approach you could talk with the AHJ about as an AMM.

Hunt

5/2/2022 09:17:29 am

Good call.. The screen material and percentage of openness needs to be identified first. Possible deluge?

Glenn Berger

5/2/2022 08:40:24 am

Potential Obstruction - yes, depending on the material and the openness of the screen material.

franck

5/2/2022 04:21:19 pm

As indicated by Dan, if the material is combustible (plastic for example), this is not a problem as it will burn quickly so that the sprinkler above can operate without problem

I made of metal (or even wood, as it will remains for a ling time), this could create an obstruction and should be considered as such.

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 © 2023 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.

Is Horizontal Screen an Obstruction to Sprinklers?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES