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There is a seemingly willful gap in information in scoping code (IBC) for small group R structures: those on the threshold of IRC/IBC: I am working on an existing 4 unit building where we do not have verified assembly information so the construction is assumed to be V-B.
The owner would like to renovate the existing basement, which is ~50% above grade, into an apartment with a new exterior exit. Three of the units share a common interior exit stairway & the upper ones are served by a fire escape. The 4th unit is built like a townhouse on the rear of the building and does not share any exit components. If an existing 4-unit residential building (currently not sprinkler protected) adds a 5th unit in the basement — and that unit does not share exit components — is there a code path that allows the project to proceed without installing sprinklers throughout the entire building? Or, a way to construct the new unit in an existing fire area in a way that does not increase risk (ie: 2-hour separation)? While the group is a trigger for requiring a system, looking at Chapter 5 as a scoping reference, the total fire area is below the threshold for a sprinkler system in group R-2 with V-B construction. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
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Working on the fire protection for a new industrial building. I only have two small areas to protect with sprinklers:
1. 400 ft² hydraulic room 2. 520 ft² transformer room Both are considered Extra Hazard due to the presence of flammable liquids. My understanding of NFPA 13 forces me to use 2500 ft² and 0.50 gpm/ft² as the minimum water supply. This will give me 1250 gpm of water to apply to very small rooms, which doesn't make much sense to me. Am I understanding this right? Is there a way around it, or a different way of calculating the water supply need? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe How should the new provisions in FMDS 2-0 (2025 Edition) regarding skylights in storage areas (sections 2.5.4.1.7 and 2.5.4.1.8) be correctly interpreted? I have two cases based on the flowchart from the snippet below. In both scenarios, sprinklers will be required (even in the case highlighted in the green rectangle, which is optional). My question is: Should they be installed at the base of the skylights, at the same level as the surrounding ceiling-level sprinklers (similar to Option 2 for skylight protection in the 2023 edition of FMDS 2-0)? Or should they be installed inside the skylight, close to the highest point of the skylight (similar to Option 1 for skylight protection in the 2023 edition of FMDS 2-0)? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  We have a 4-story motel that the architect of record stipulated the sprinkler system was to be designed in accordance with NFPA 13R. The building is wood construction with open wood joists. We have a kitchen and several laundry rooms that have suspended ceilings, which would be designed in accordance with NFPA 13 Ordinary Hazard Group I Occupancy.
What about the combustible area above the ceiling in the combustible area above the suspended ceiling in the laundry room? Are sprinklers required in this space? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Our industry gets stronger every time you share what you know. Thank you to our top February 2026 Contributors!
If the required dimensions of a remote area in either orientation exceeds half the distance to the next sprinkler, does 13 require picking up additional sprinklers?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We have a 24.5' wide porch that needs to be sprinklered. Can we use a dry sidewall sprinkler?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Is a hose stream allowance required for foam/water deluge system, in either NFPA 13 or NFPA 16?
Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Hi, I have a fire pump house separated from the protected building. The main alarm check valve is located in the protected building.
So, for the connection supplying eight (8) sprinklers protecting the fire pump room itself, which will be upstream of the building alarm check valve, as I understand it, I have two options: Option-1: OS&Y valve + separate alarm check valve assembly + Water flow switch Option-2: OS&Y valve + check valve+ water flow switch Is an alarm check valve required, or just a check valve, to serve the 8 sprinklers in the fire pump room if there's a waterflow switch provided either way? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have an NFPA 13D system covering an ADA house that has two pumps in the basement. I am struggling to understand why the two pumps were installed in parallel.
Would this just be to increase Total Dynamic Head (TDH)? Why would you need to increase TDH on a residential system? Basically, the customer wants the pumps replaced with new ones because they're old, and I guess what my question really boils down to is what info do I need to figure out to replace these pumps with the correct size pump(s) to satisfy system demand? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe NFPA 20 – Does the 10 pipe diameter suction requirement have to be one continuous straight run?
I’m looking for clarification on the NFPA 20 requirement for 10 pipe diameters of straight pipe on the suction side of a horizontal split‑case fire pump. NFSA’s Layout Book states: “The length of pipe that needs to be 10 pipe diameters long can be either vertical or horizontal, or some combination of the two, as long as there are no more elbows or tees with a horizontal change in direction in the length of pipe.” This makes sense—but when I look at NFPA 20’s own figures (specifically the “Right and Wrong Pump Suctions” illustration), one of the “Right” examples shows a 90° elbow dropping directly into a tee located right at the pump suction flange. In that configuration, there is no 10‑diameter straight run at all. My questions: Where in NFPA 20 is it actually stated that the 10 pipe diameters must be a single, continuous straight run of pipe? NFSA says the 10 diameters can be vertical, horizontal, or a combination, but NFPA 20’s figure seems to show exceptions. Is NFPA 20’s 10‑diameter rule only triggered by elbows/tees that introduce a horizontal component to the change in direction? (For example, a vertical elbow turning up does not trigger the 10D requirement.) Is this 10‑diameter rule only applicable to horizontal split‑case pumps? Or does it apply to all pump types? I’m trying to reconcile the NFSA explanation with NFPA 20’s figures and determine whether certain configurations truly require the 10D straight run. Thanks in advance for any clarification. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe My fire department is requesting that a new large development in our district install a more robust water storage tank (20,000 gallons more than required by code, along with a wet hydrant adjacent to the tank).
We will use the extra water for fires in the area. My question is - how can the fire department refill the tank after the nearby fire is under control? Can we require a FDC adjacent to the tank (5"storz connection) so we can refill the water storage tank quickly from FD tankers? There is no public water supply in area-wells only. Thanks! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I have a 2-story space with a mezzanine. The ceiling above the mezzanine is unconditioned. I need to sprinkler the space and plan to do so using two rows of sidewall sprinklers along the ceiling, pointing towards the middle of the opening. There is an obstruction running down the middle of the ceiling. (See diagram below for a section view of the space.) Using Figure and Table 10.3.6.1.3 from NFPA 13 2019, the sidewall sprinklers would need to be spaced 8' to 8'-6" away from the obstruction, which isn't possible. However, I'm not sure if Figure 10.3.6.1.3 applies to my situation, given that I am spraying from both sides of the obstruction. Section 10.3.6.1.5 might apply to my situation, but the wording makes it seem like it is referring to obstructions along the same wall the sprinkler is on. Does Section 10.3.6.1.5 apply here? Thanks in advance! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  I have a client who has created a spray finishing area in the back of a semi-trailer. The spray booth area is noncombustible construction, but the surrounding area is typical semi-construction (combustible plywood). Are there any fire-related code requirements regarding spray finishing in a semi-trailer? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  I am working on a project with non-enclosed vertical floor openings, approximately 6-ft by 10-ft. Looking at FMDS (Factory Mutual Data Sheet) 2-0 and NFPA 13, I found similar language that I need help understanding.
FMDS 2-0 2.5.1.7.4.1: A non-enclosed vertical floor opening does not need a combination of draft curtains and closely spaced sprinklers if
(B) seems to contradict (C) as I read it. (B) seems to be describing an area of 400 ft², which leads me to believe I am misunderstanding something. NFPA 13 words it differently, but it still didn’t click. NFPA 13 2022: 9.3.5.4 Large Openings. Closely spaced sprinklers and draft curtains are not required around large openings such as those found in shopping malls, atrium buildings, and similar structures where all adjoining levels and spaces are protected by automatic sprinklers in accordance with this standard and where the openings have all horizontal dimensions between opposite edges of 20 ft (6.1 m) or greater and an area of 1000 ft² (93 m²) or greater. How should the 20-ft horizontal dimension requirement be interpreted, and how does it work together with the 1,000-ft² minimum area requirement without creating a contradiction? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe For a diesel engine–driven fire pump installation, is it permitted by NFPA 20 to route the PRV discharge piping back to the fire pump suction piping, at a point downstream of the suction control valve, particularly in cases where the fire pump test/meter header discharge is already routed back to the pump suction?  Regarding existing high-rises going through an occupancy change (B to R-2), am I correct that all an engineer has to meet is the 65 psi at the top most floor per IEBC 2021 803.3 Exception 1: "A pump shall not be required provided that the standpipes are capable of accepting delivery by fire department apparatus of not less than 250 gallons per minute (gpm) at 65 pounds per square inch (psi) (946 L/m at 448 KPa) to the topmost floor in buildings equipped throughout with an automatic sprinkler system or not less than 500 gpm at 65 psi (1892 L/m at 448 KPa) to the topmost floor in all other buildings. Where the standpipe terminates below the topmost floor, the standpipe shall be designed to meet (gpm/psi) (L/m/KPa) requirements of this exception for possible future extension of the standpipe."
The code section makes no mention of high-rise difference and the commentary states: "Exception 1 allows the installation of a standpipe system without a fire pump if sufficient water with sufficient pressure could be delivered by means of fire department apparatus pumps to the topmost floor of the building. Under this exception, the location of the work area is irrelevant, and the topmost floor must be considered whether the work area is located at the topmost floor or not." I can't find anything that an existing building needs to meet the 100 psi requirement of the IBC, and this would trigger the need for a fire pump if I can meet 65 psi already. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe For the 5-year Underground and exposed piping flow test NFPA 25 7.3.1 - are you to run the fire pump while recording your static, residual, and GPM's?
Without a fire pump, can I utilize the main drain as long as I can flow enough to have the 10% drop between the static and residual, along with using a pitot or a flow meter at the discharge point of the main drain? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe We’re so grateful to our January top contributors for kicking off the year by making this community such a helpful place! Thank you! Here are January's top contributors on the Forum:
I'm designing a fire protection wet pipe system for a large gathering space (light hazard occupancy) that's architecturally sensitive. The architect is requesting sidewall sprinklers where possible to minimize visual impact, but the space is too large for sidewalls alone (even extended coverage sidewalls can't adequately reach the center areas).
Can I combine sidewall sprinklers around the perimeter with ceiling pendent sprinklers in the interior to achieve complete coverage throughout the room? Or does code require me to use one sprinkler type throughout the entire space and prohibit mixing of sidewall and ceiling sprinklers in the same room? The room is about 35 feet wide and 35 feet long with 13 foot ceilings. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm seeking clarification on where in code it dictates the need for a strobe device in the bathroom of a R-1 occupancy type (for the number of sleeping units required to have visual devices from IFC Table 907.5.2.3.2).
IFC 2024 Section 907.5.2.3.2 states "Habitable spaces in dwelling units and sleeping units" ... shall be provided with visible alarm notification. The definition of "habitable space" from Chapter 3 is "A space in a building for living, sleeping, eating, or cooking. Bathrooms, toilet rooms, closets, halls, storage or utility spaces, and similar areas are NOT considered habitable spaces". The 2010 ADA Standards for Accessible Design, Section 702.1, states that alarms in guest rooms required to provide communication features shall comply with Sections 4-3 and 4-4 of NFPA 72 (1999 edition) or Sections 7.4 and 7.5 of NFPA 72 (2002 edition). Neither of these sections mandates a strobe in the bathroom. I would like some context on when this became an industry standard (if it has) and where the code reference driving it comes from. Thanks in advance!!! Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Our company installs all Intermediate temp. sprinklers throughout buildings as a rule - primarily to avoid the issue of having an ordinary temperature sprinkler end up in a ceiling tile 12 inches from the edge of a diffuser. We're basing this on NFPA-13 (2019) Section 9.4.2.1.
Unless the requirements of 9.4.2.2, 9.4.2.3, 9.4.2.4, or 9.4.2.5 are met, ordinary- and intermediate-temperature sprinklers shall be used throughout buildings. A.9.4.2.1 It is acceptable to install ordinary-temperature sprinklers throughout a building, intermediate-temperature sprinklers throughout a building, or a mix of ordinary- and intermediate-temperature sprinklers throughout a building. We've received some pushback on this recently from different AHJ's stating that ordinary temperature sprinklers are to be installed unless higher temperature sprinklers are required - are we interpreting the above code section incorrectly? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe I'm designing an in-rack sprinkler system for an automatic storage retrieval system, up to 30 ft tall. I've designed the system per FM Data Sheet 8-34. The storage commodities are open-top, non-expanded combustible bins. I referenced Section 2.2.7 since this is a mini-load automatic retrieval system. I'm currently using Figure 39 for the in-rack sprinkler layout. I didn't see anywhere what hose stream allowance to use for in-rack sprinklers only. I currently am using 500 gpm in my design. I attached the FM data sheet 8-34. I based the design from page 85, table 40. Figure 39, unexpanded plastic, 15ft distance between rack sprinklers. Is 500 gpm hose allowance applicable here? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe  Is a fire supply allowed to have any joints, offsets, or fittings underneath the building foundation other than the 90-degree elbow looking up to the flange?
What's the code or standard basis for allowing or not? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe Clarification on Use of Passive Natural Smoke Relief Openings in Walls Below ESFR Sprinkler Elevation
I am requesting clarification regarding the compatibility of 'passive natural smoke relief openings located in exterior walls' of buildings protected by ESFR systems. NFPA 13 prohibits the use of automatic roof-mounted heat or smoke vents unless they use high-temperature, standard-response sprinklers, due to possible premature venting interfering with sprinkler operation. Does NFPA 13 or NFPA 92 prohibit or restrict the use of passive, fixed, natural smoke relief openings located in exterior walls (not roofs), which are positioned below the elevation of the ESFR sprinklers and have no operating mechanism (neither automatic nor manual)? These openings are permanently open (fixed, non-operable), not connected to any fire detection or alarm system, intended solely to allow natural smoke movement during fire events, and located entirely below the sprinkler deflector level. Looking to see if these openings are acceptable and whether they otherwise would introduce any related concerns on sprinkler performance or smoke control strategy. Much appreciated. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe |
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