Taylor, Rick is on the right track on this. Check out 9.2.2 in NFPA 13-2019. This section allows sprinkler omissions from underneath ground floors, exterior docks, and platforms, with your decks likely falling into the platform category. There are a few requirements, one being that the area is protected against debris accumulation like Rick mentioned. The other big one for you will be that the flooring over the space needs to be “of tight construction” which is nicely vague. If your decks are trex style, you will probably want to make sure that the board spacing is pretty close.
There isn’t a height stipulation in 9.2.2, so you are going to have to make a judgment call as to when this rule stops applying and 9.2.3 for exterior projections starts applying. Personally, I would start to feel uncomfortable using this omission if the height below the deck gets to a point where someone could walk below them without needing to crawl. Hope this helps! Eric Rieve Rieve Fire Protection From: Rick Matsuda <[email protected]> Sent: Wednesday, March 8, 2023 10:21 AM To: Discussion list on issues relating to automatic fire sprinklers <[email protected]> Subject: [Sprinklerforum] Re: Low Decks As an old AHJ, I would require you to screen in any unsprinklered decks that are permitted to prevent accumulation of debris beneath them. Rick Matsuda On Mar 8, 2023, at 9:04 AM, [email protected]<mailto:[email protected]> wrote: This seems like one of those great communication with AHJ/Owner opportunities. A deck is an exterior projection. I am assuming the deck is wood, and no fire-resistant stuff. The only thing height wise is the 24” for obstructions over 4 feet, and the 48” for stages, with stipulations. IMHO, the spray pattern development is not as big a concern with properly spaced and the lower heights as suppression will most likely occur. At 8 feet, there will Def be storage under them if this is a residential environment. The sprinklers will more than likely serve as impingement type, as the channels formed by the studs, and the open nature negates proper ceiling jet. R/ Matt Please rate our customer service<https://survey.medallia.com/?emailsignature&fc=3539&bg=Fire%20and%20Fabrication> Matthew J. Willis, CWBSP, CET Engineering Designer IV FERGUSON FIRE DESIGN, LLC A Wholly Owned Subsidiary of Ferguson Fire & Fabrication, LLC 401 N 5th Street Suite 448 Wausau, WI 54403 C: 307-236-8249 [email protected]<mailto:[email protected]> www.FergusonFire.com<http://www.fergusonfire.com/> From: Taylor Schumacher <[email protected]<mailto:[email protected]>> Sent: Wednesday, March 8, 2023 6:15 AM To: '[email protected]' <[email protected]<mailto:[email protected]>> Subject: [Sprinklerforum] Low Decks Is there any guidance on sprinkler protection under decks that are really close to finished grade? I have a 13 project with combustible decks that range from 1 foot to 8 foot above finished grade. Common sense tells me these short ones won’t allow spray pattern development and replacing/testing will be a nightmare but I have nothing to fall back on. Thanks, Taylor Schumacher Security Fire Sprinkler<http://www.j-berd.com/> 1 Industrial Blvd | Sauk Rapids, MN 56379 Office: 320.656.0847 | Direct: 320.640.7050 _________________________________________________________ SprinklerForum mailing list: https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org To unsubscribe send an email to [email protected]<mailto:[email protected]>
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