What Is a Combined Sprinkler and Standpipe System?

A combined sprinkler and standpipe system is a standpipe system whose risers also feed the building’s automatic sprinklers, so the same risers, water supply, fire department connections (FDCs) and any fire pump serve both the firefighters’ hose valves and the sprinklers on every floor. The National Fire Protection Association (NFPA) standard for standpipe and hose systems, NFPA 14, defines the arrangement in Chapter 3 as a standpipe system in which one network of pipe serves both the hose connections and the automatic sprinklers.

Each floor takes its sprinklers off the riser through a floor control valve assembly, while the hose valve stays on the riser itself, so a floor’s sprinklers can be shut for work without taking the hose valve out of service. Most high-rise and many mid-rise buildings designed under current codes use the arrangement. Building staff often refer to the combined riser simply as the sprinkler riser, which hides the fact that it is sized and tested as a standpipe.

What a Combined Sprinkler and Standpipe System Is

A combined system is a standpipe first. The riser is sized, supplied and calculated as a standpipe under NFPA 14, and the sprinkler system on each floor is a branch off that riser, designed under NFPA 13 like any other sprinkler system. The hose valves sit on the riser at each stair landing, and the sprinklers start from a separate valve assembly on the same riser.

The design logic is economy. A high-rise needs a standpipe in each exit stair and sprinklers on every floor, and running a second set of risers beside the standpipes duplicates pipe, valves, shaft space and in many cases a pump. One set of larger risers serves both, and the standpipe demand usually governs their size anyway.

Because the sprinklers need an automatic water supply under NFPA 13 (2022) Chapter 5, a combined riser is kept full of water and connected to the public main, a tank or a fire pump. The standpipe types the codes allow, and where a dry or manual standpipe is still permitted, are set out in which standpipe types the code allows: wet, dry or manual.

The two demands on a combined system are compared, not added. In a building sprinklered throughout, NFPA 14 Chapter 7 permits the standpipe demand (500 gpm for the most remote standpipe plus 250 gpm for each additional one, up to 1,000 gpm) to serve the sprinklers as well, and where the sprinkler demand including its hose stream allowance is larger, the water supply has to meet that larger demand. In a building that is only partly sprinklered, the same chapter adds a sprinkler allowance to the standpipe demand instead. The arithmetic, with a worked example, is in how to calculate standpipe demand and pressure.

What a Combined System Includes

A combined system adds a short list of sprinkler parts to the standpipe. The table names each component, what it does in the combined arrangement and where the codes address it, using NFPA 14 and NFPA 13 chapter references because paragraph numbers move between editions.

The floor control valve assembly is the part that turns a standpipe into a combined system. NFPA 14 Chapter 6 gives each sprinkler connection off a combined riser its own control valve, and NFPA 13 (2022) Chapter 16 calls for a floor control valve, check valve, pressure gauge, main drain valve and flow switch on each floor of a building more than 2 stories tall (the 2019 edition lists the same items without the gauge), with limited exceptions. Manufacturers sell the pieces as one preassembled unit, usually with a sight glass, which is why the trade calls it an assembly.

Pressure is the other floor-level issue. On the lower floors of a tall combined system, the riser pressure needed to reach the top hose valve can exceed the 175 psi rating of standard sprinkler components. The floor connection then gets a pressure-reducing valve downstream of the floor control valve, or the floor is built with components rated for the higher pressure.

Figure 1: Anatomy of a Combined Riser

Where the Code Defines a Combined System

NFPA 14 holds the definition and the riser rules. Chapter 3 defines a combined system, Chapter 6 covers the valves, the sprinkler connections and the FDC, and Chapter 7 sets the minimum riser size and the demand rule for a building sprinklered throughout, in both the 2016 and 2019 editions.

NFPA 13 governs everything downstream of the floor control valve. The sprinkler piping, the spacing and density, and the floor control valve assembly itself follow the sprinkler standard, which places the installation of piping and valves in Chapter 16 of the 2022 edition. The sprinkler hydraulic calculation is run to NFPA 13 first, then compared with the standpipe demand.

The building code supplies the triggers and the supervision rules. In the 2021 IBC, Section 903 requires the sprinklers, Section 903.4 requires valve supervision and waterflow alarms, and Section 903.4.3 requires a supervised indicating control valve at the riser connection on each floor of a high-rise. Section 905 requires the standpipe, and Section 905.9 requires the valves controlling its water supply to be supervised open.

New York City modifies both standards through 2022 NYC Building Code Appendix Q, which names NFPA 13 (2016) in Section Q102.1 and NFPA 14 (2016) in Section Q105.1. For combined systems, the modified NFPA 14 allows the smaller riser only in fully sprinklered, hydraulically calculated buildings whose floors are less than 150 ft above the lowest level of fire department vehicle access (Section 7.6.2.1). Section 7.6.1 as modified requires every standpipe in a building with floors more than 150 ft above grade plane to be at least 6 in.

Appendix Q also deletes the words that bring the hose stream into the sprinkler side of the NFPA 14 comparison (Section 7.10.1.3.1.1), so in New York City the standpipe demand is compared with the sprinkler demand alone. FDC caps on a combined system are painted yellow and the connection is marked “COMBINATION STANDPIPE AND SPRINKLER SYSTEMS” (Sections 4.8.3 and 6.4.5.2). Valves controlling sprinklers fed from the standpipe have to be listed for standpipe service in their pressure zone and sit ahead of any pressure-reducing valve (NFPA 13 (2016) Section 8.16.1.1.1.8 as modified).

Outside New York City, the NFPA 13 and NFPA 14 editions follow the building code each state adopted, through the referenced standards in IBC Chapter 35. New York State and New Jersey apply NFPA 13 (2022) under the 2024 International Codes (I-Codes), and Pennsylvania applies NFPA 13 (2019) under the 2021 IBC. In Maryland, the county building permit reviews sprinklers to NFPA 13 (2019) through the 2021 IBC, while the State Fire Prevention Code (NFPA 1, 2024) references NFPA 13 (2022). Delaware applies NFPA 13 (2025) through Regulation 701 and approves fire protection through State Fire Marshal plan review.

Editions as of November 2026. Local amendments other than New York City’s Appendix Q are not shown.

DGA designs combined sprinkler and standpipe risers, the floor control valve assemblies on them and the fire pumps that feed them across New York, New Jersey, Pennsylvania, Maryland and Delaware. Project briefs get confirmation and preliminary code feedback within one business day. See DGA’s commercial and high-rise work →

How a Combined System Differs From Separate Risers and Sprinkler-Fed Hose Valves

Two arrangements look like a combined system on a riser diagram and are not one. The first is a building with separate standpipe and sprinkler risers: the standpipes carry only hose flow, and the sprinklers have their own riser, usually smaller, with its own floor control valves and its own hydraulic calculation. The second is a sprinkler system with hose connections taken off the sprinkler piping, which NFPA 13 (2022) Chapter 16 permits in limited cases but which is designed to the sprinkler demand and is not a standpipe.

Figure 2: Combined, Separate or Sprinkler-Fed Hose: Side by Side

Feature	Combined system	Separate standpipe and sprinkler risers	Sprinkler system with hose connections
What the riser carries	Hose flow and sprinkler flow in the same pipe	Hose flow only in the standpipe; sprinkler flow in its own riser	Sprinkler flow, with a hose allowance drawn from sprinkler piping
Governing standard	NFPA 14 for the riser; NFPA 13 downstream of each floor control valve	NFPA 14 for the standpipes; NFPA 13 for the sprinkler riser and floors	NFPA 13 only
Minimum riser size	6 in., or 4 in. where sprinklered throughout and hydraulically calculated (NFPA 14 Chapter 7)	Standpipe 4 in. (NFPA 14 Chapter 7); sprinkler riser set by the sprinkler calculation	Set by the sprinkler calculation
Design demand	The larger of the standpipe demand and the sprinkler demand with hose, in a building sprinklered throughout (NFPA 14 Chapter 7)	Each system calculated on its own; a shared pump or tank is checked against both	Sprinkler demand plus the NFPA 13 hose allowance
Floor control valve assemblies	On the standpipe riser at each floor	On the sprinkler riser; the standpipe has none	On the sprinkler riser
Fire department connection	The same FDCs feed both	Separate FDCs, or a shared one where the fire department accepts it	The sprinkler FDC
Meets a building code standpipe requirement	Yes	Yes, through the standpipe	No
Typical building	High-rise and mid-rise office, residential and hotel towers	Low-rise buildings, buildings with a dry or manual standpipe, and additions on an existing sprinkler riser	Warehouses and light or ordinary hazard buildings with no standpipe requirement

The practical test is the riser calculation. If the riser was sized and calculated for the NFPA 14 standpipe demand and the sprinklers branch off it through floor control valve assemblies, the system is combined. If the riser was sized for the sprinkler demand and hose valves were added later, it is a sprinkler system with hose connections, and the added valves do not turn it into a standpipe.

Hose connections on sprinkler piping do not meet the flow and pressure NFPA 14 requires of a Class I standpipe, so they cannot stand in for the standpipe the building code requires. DGA’s explainer on what a standpipe system is and how NFPA 14 Classes I, II and III differ covers the standpipe side of the comparison.

When a Combined System Is Required

No code requires the combination itself. The building code requires sprinklers and a standpipe as separate obligations, and NFPA 14 permits one set of risers to serve both; the designer chooses the combined arrangement because it saves pipe, valves and shaft space. Most high-rises use it, since a high-rise has to be sprinklered throughout under 2021 IBC Section 403.3 and needs a standpipe in every exit stair.

The standpipe triggers, including the height above fire department vehicle access and the story count in 2021 IBC Section 905.3.1, are set out in when a building needs a standpipe under IBC 905.3. In a building more than 420 ft tall, 2021 IBC Section 403.3.1 requires each sprinkler zone to be fed by at least 2 risers, each supplying sprinklers on alternate floors, and combined risers in separate stairs often fill that role. In New York City, Appendix Q permits combined systems in occupancy Groups A, B, E, F, I, M, R and S (NFPA 13 (2016) Section 24.2.5.2 as modified).

Common Misconceptions

“Shutting a floor’s sprinkler valve shuts the hose valve.” No. The hose valve is on the riser side of the floor control valve, so isolating one floor’s sprinklers for a tenant fit-out leaves the hose valve live. Shutting a riser control valve is different: it takes the hose valves and every floor’s sprinklers on that riser out of service, which NFPA 25 (2023) Chapter 15 treats as an impairment.

“Every combined riser has to be 6 in.” Not always. NFPA 14 Chapter 7 permits a 4 in. riser where the building is sprinklered throughout and the system is hydraulically calculated, and New York City keeps that allowance only where floors are less than 150 ft above fire department vehicle access.

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This article is general information, not a substitute for a project-specific code analysis. Code editions, local amendments and reviewer practice change; confirm the adopted code and the authority having jurisdiction for each project.