Three Buildings Under One PIV and One FDC?

6/12/2025

Our project is a school campus with nine buildings.

The Civil Engineer has designed the underground so that three buildings are controlled from a single PIV and an FDC. Additionally, they want butterfly valves on each fire sprinkler riser.

Does shutting off three buildings become an issue, and is this within the NFPA 13 parameters to dictate this one way or another?

Thanks in advance.

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10 Comments

Glenn Berger

6/12/2025 08:11:02 am

Please tell me that these 3 buildings are attached and may look like a single entity from a site plan.

Someone else will weigh in on NFPA specifics, and also ask which versions of codes that the design is based upon.

IMO, this is just wrong.

Chad

6/12/2025 08:29:22 am

Get the FD/AHJ to weigh in and tell the engineer what they will need for an FDC if they are really separate buildings not just looks like it as Glenn said. It’s the AHJ’s call not the PE.

Valves on risers, not the FDC, is fine as long as it’s supervised.

I’m sure someone else will throw up references.

Ryan Grant

6/12/2025 08:29:26 am

From an AHJ perspective, I would separate PIVs and FDCs for each building in case you need to shut down the system for any reason, which would require a fire watch for all three buildings. This could be a greater expense to the owner vs the additional PIVs and FDCs.

MOHAMMAD MASHIRUL HAQUE

6/12/2025 08:42:17 am

I had a project in a residential community where we designed a free-standing alarm check valve assembly with a fire department connection (FDC) located near the fire apparatus access road. For each building, we had a provision for a zone control valve assembly. This type of arrangement could be in compliance with NFPA 13 (2019) as follows:
1. The maximum system protection area considered for light hazard is 4830 sq.m, as per NFPA 13 (2019), Section 4.5.1.
2. As per NFPA 13 (2019), Section 16.9.11.3: “The floor control valve, check valve, main drain valve, and flow switch required by 16.9.11.1 shall not be required where the total area of the floor combined does not exceed the system protection area limitation.”
3. As per NFPA 13 (2019), Section 4.5.6.2: When acceptable to the Authority Having Jurisdiction (AHJ), detached structures shall be permitted to be supplied by the fire sprinkler system of an adjacent building.
AHJ Concern – Why would an authority having jurisdiction have concerns about multiple buildings using the same fire sprinkler system? From the standpoint of an AHJ, the primary problem occurs if each building is or becomes owned by different owners. If the source building owner stops maintaining the water supply and the buildings are under separate ownership, it becomes very difficult to enforce fire code maintenance requirements for the dependent buildings. If the AHJ allows the use of the exception in Section 4.5.6.2, it should be only in situations where it is unlikely or impossible for the ownership of the individual buildings to split, or where legal easements are recorded.
4. A free-standing alarm check valve assembly shall have an OS&Y gate valve, alarm check valve, gauges, retard chamber, tamper switch, flow switch, pressure switch, water motor gong, test and drain valve, drain connection, etc., and shall be equipped with a two-way FDC with a check valve facing toward the fire apparatus access road. This arrangement shall serve a combination of three accommodation buildings, where the total area does not exceed the maximum limitation for light hazard occupancy.
5. Each building shall have a dedicated zone control valve assembly, consisting of a butterfly valve with supervisory switch, check valve, pressure gauge, inspector’s test and drain valve, and flow switch, in order to integrate each building with the fire alarm system allowing the status of each building to be monitored individually and isolated for maintenance individually.

Jesse

6/12/2025 08:42:47 am

I'm curious as to whether there are hydrants on the underground system. If so, I imagine each hydrants has an NRS valve.

I don't necessarily with the single PIV, as its not acting as a sprinkler control valv. The butterflfy valves are. I had a project with a lot of underground feeding 3 or 4 buildings and some hydrants. The AHJ didn't really care about PIVs, they just wanted keybox valves. All of the AS risers had butterfly valves. My point being, see what the AHJ wants

Paul Pinigis link

6/12/2025 08:49:52 am

First, you need to confirm that these are three separate "buildings" and not just three separate "structures". Review the building code analysis for the project.

Louie Lincoln

6/12/2025 09:22:09 am

If the valve in 1 building is closed then that building has no FDC.

Anthony

6/12/2025 09:53:43 am

I don't think you have code compliance here. Separate buildings should have separate control valves and FDC's.

Is this a case where say on a campus the buildings are touching or connected but coded as "separate buildings" in this instance I could see this being plausible.

Jack G

6/12/2025 11:32:11 am

For my money, I would not install this as described above.
First of all, I would install a PIV for each lead in.
Each riser should have its own FDC, Labeled for area it services.
If there are hydrants off the underground so they are near the fdc s , I would have a fire service valve, or a meter pit with BFP, Meter, Check valve , and an fdc( common) if AHJ agrees

Streeter

6/12/2025 02:03:48 pm

It is very unlikely that these FDCs are piped correctly. NFPA 13 (2025) 16.12.5.1 says that FDC piping needs to be connected to the system side of the water supply check valve if it is a single zone system.

It there are multiple systems in a single building, it is permitted to be piped between the supply valve and system control valves.

From what I gather on the question, you have three buildings each with an individual riser. The only way this might be compliant is if the AHJ approves the location for a remote FDC that is connected underground to the building system piping (Figure A.16.12.5.5(a)) after a system control valve and check valve (both of which need to be in an accessible pit for maintenance.) And the FDC check valve needs to be in an accessible pit for maintenance (Figure A.16.9.5)

I would also say that there should be clear signage on the FDC as to what buildings/zones that FDC feeds.

The ways to not have the Civil Engineer do this is to contact the AHJ, who should require FDCs on each building per their discretion per section 16.12.5.7, or to reference 16.12.5.1 which says the FDC should be on the system side of piping, the whole purpose of which is so no valve has the ability to stop the FDC from supplementing any sprinkler system., even in the worst case of the riser valve or any other upstream valve being off at the time of a fire.

You could also consult just about any other FPE and they will tell Civil just about the same as above for you.

Three Buildings Under One PIV and One FDC?

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