Is Sprinkler/Standpipe Combined or Separate?

3/3/2025

What specific criteria or code references determine whether a standpipe system is classified as 'separated' rather than 'combined'?

I've seen AHJs state that even though the sprinkler system and the standpipe have separate vertical riser assemblies (control valve, check valve, and supervision), they are fed from the same underground supply (one underground service main) and will still be considered combined.

We are working on a project where the AHJ has deemed the building 'partially sprinklered,' requiring the standpipe to be upgraded from 4" to 6" (which would necessitate a pump) but only if it is a combined system. We are looking for clarification or language that supports the distinction between a combined and a separated standpipe system to explore options that may avoid the need for a pump.

Additionally, does anyone have thoughts on how we might be able to keep the standpipe at 4" or explore alternative approaches to avoid the pump requirement?

Thanks in advance.

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9 Comments

Peter Howard

3/3/2025 06:50:56 am

Do the floor control valves or control valves of the sprinkler system get fed from the standpipe? Then it is a combined system.

If the sprinkler system is not tied into the standpipe system, they're separate.

This is an oversimplification and I'm sure someone may use code definitions in a later post.

Mike Morey

3/3/2025 08:13:40 am

From 14 2024:

3.3.27 Standpipe. - The system piping that delivers the water supply for hose connections, and for sprinklers on combined systems, from floor to floor.

3.3.28.3 Combined System. A standpipe system that supplies both hose connections and automatic sprinklers.

If the sprinklers are on a separate valve and vertical feed it is not a combined system IMHO.

Christopher Hallock

3/3/2025 08:14:16 am

Is the standpipe system required to be an automatic standpipe system? Also, can you clarify what hydraulic demand is necessitating the fire pump? Just an increase in pipe size shouldn't necessitate a fire pump.

Jesse

3/3/2025 08:16:41 am

Its not really an issue if they're tied into the same UG. Using that reasoning, we could say that 10 AS systems in a single building are all "one system" because they're all served by the same UG.

Combined systems - AS and SP - share a supply riser serving upper floors, and usually only one. So, even though you'll have standpipe risers in (or near) each standpipe, usually only one of them is interconnected to the AS system.

Glenn Berger

3/3/2025 08:18:33 am

Agree with Peter on the practical definition of separate v. combined systems.

The question did not mention what type of standpipe system that you have in the design. the type of standpipe (Class I vs Class III, Manual vs Automatic) and building height and area can come into play.

The fact that you did say that the building is not completely sprinklered is a factor.

Casey Milhorn

3/3/2025 08:26:56 am

The increase in pipe size has nothing to do with the need for a fire pump. I think they are referring to a manual standpipe system and the requirement for the sizing to be at 6" in an un-sprinklered (or partially sprinklered) building. (This is from memory, so verify in the applicable NFPA 14 edition). I'm confused on the ask from the AHJ though.
BUT, typically if the building is not deemed a hi-rise, then a manual wet system is used. You would perform a calculation using the responding fire departments pumper truck supply capabilities. Sometimes 4" works, sometimes you need 6", and sometimes you can't make it work at all because of inadequate pumping capacity by the responding fire department. A fire pump might be required in this case. Be careful here, sometimes you will have a fire department tell you 175 psi @ 1000 gpm, or something generic, when in reality they will continue pumping up to 250 psi or more as needed. Make sure everything is listed or approved for the max psi they might see.
Then of course you would do some verification calculation(s) on the most demanding automatic sprinkler system(s) to verify it also works without a fire pump, or supplemental supply from FDC.

Joe

3/3/2025 08:42:05 am

What code is requiring the standpipes IBC/IFC or NFPA 1/101?

Then you can look at the type of standpipe system you need manual or automatic and there related sub categories.

These codes with also tell you what class of standpipe. Then you can go to NFPA 14 for design details.

Jack G

3/3/2025 10:23:53 am

Please check With your AHJ. If there are multiple stair towers and are required for egress then a stand alone sprinkler riser is not permitted. All the risers are combined and must have hose valves.
If it is just a standalone stair tower and it does not require the proper fire rating, or a standpipe, fire hose valves are required. ( along with floor control vas and flow switches and drain assemblies)
Past experience with AHJ s is that only piping permitted in a stair tower ( to penetrate the enclosure , in and out ) is the piping required to protect it ( sprinkler the stairs ) and a stand alone riser, must also have fire department valves.
So consult your IBC, and AHJ s.

Todd E Wyatt

3/4/2025 07:01:02 am

The scoping requirements where an Automated Sprinkler System (ASPS) and/or a Standpipe Systems (SS) are required are per the scoping Code's (e.g. IBC-2024) "Where Required" sections :

IBC-2024
Chapter 9 Fire Protection and Life Safety Systems

Section 903 Automatic Sprinkler Systems
903.2 WHERE REQUIRED
Approved automatic sprinkler systems in new buildings and structures shall be provided in the locations described in Sections 903.2.1 through 903.2.12.

Section 905 Standpipe Systems
905.3 Required Installations
Standpipe systems shall be installed WHERE REQUIRED by Sections 905.3.1 through 905.3.7.

905.3 also states that "Standpipe systems are ALLOWED TO BE COMBINED with automatic sprinkler systems" but does not include prescriptive requirements as to HOW these systems are to be "combined."

Chapter 9 Fire Protection and Life Safety Systems includes (31) references to "separate" or "separated" but (0) are attributed to ASPS & SS.

I recommend asking the AHJ where in the scoping Code and/or the referenced standards (e.g. NFPA 13 for ASPS and NFPA 14 for SS) does it REQUIRE these (2) systems to be COMBINED.

Is Sprinkler/Standpipe Combined or Separate?

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