Each Townhouse Have Its Own NFPA 13D System?

11/3/2025

My coworker and I are disagreeing about townhomes.

Can each townhouse (3 total) have its own NFPA 13D system?

Or do they need to have one total system?

Each townhouse has a 1-hr separation in the form of UL U347. I cannot find anything that says they can't each have their own, but he is saying he can't find anything to say they can, to which I have always said if it doesn't say no, then it's usually allowed.

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18 Comments

Pete H

11/3/2025 06:11:31 am

You're both right.

There's nothing preventing them from each having their own.

There's nothing requiring the townhouses to have separate systems or feeds as long as they are a singular building.

The advantage of separate systems is control. The advantage of separate feeds is waterflow. And the advantage of a singular system is cost of installation.

pHILIP

11/6/2025 09:53:42 am

The answer is in the building code (2016, 2019, or 2022 code editions related to R-2 occupancies dealing with townhomes where each townhome is allowed up to 4 stories without standpipe because each townhome is being considered as designed for R-3 sprinkler protection. I believe there may have been a code change by now.

Brett

11/3/2025 06:47:29 am

Typically it's done by teeing off from the domestic water supply within each unit, but you could do it with a dedicated feed for the townhouse depending on how your local AHJ and local water authority require it to be setup.

I recommend reading section 6.2.3 of NFPA 13D. If you do a dedicated sprinkler feed then each unit is required to have its own control valve which, in my opinion, is less than ideal because I don't want occupants to have the ability to turn off their fire sprinkler system without also turning off their domestic water.

Philip

11/6/2025 09:58:11 am

Control valve is prohibited between the domestic control valve and the sprinkler system. If the municipal water purveyor's main shutoff valve is closed, there will be no water supply to the house.

Dan Wilder link

11/3/2025 07:26:52 am

We have adjacent AHJ's and one would allow one riser per building (for all 3 units), while the one across the street would require separate riser and feeds for each unit. This is based on the adopted and amended codes for per your AHJ.

Paul J Pinigis link

11/3/2025 08:08:34 am

Because they are townhouses, they are separate BUILDINGS, not just separate units like apartments. As such, you need one system per building.

Ricardo Gonzales

11/3/2025 08:44:56 am

There are 2 trains of thoughts on this. 1: The Code restricts you to what you can do. or 2: The Code mandates what the minimum to be done. The premise of this discussion is valid both ways and how the AHJ was trained. Even in Law this conundrum occurs frequently. i.e. speed limits (thou shall not exceed) and how you parent (the minimum you need to do is:) Both are seen in the Codes as they are written because they work diligently to allow new technology with means and methods, while restricting some details or performane3 criteria.

Always check with the AHJ but present it how YOU think it should be (cost vs. benefit) and explain why. More often you'll be teaching them about the idea and how it can be constructed. Remember, they've never turned a wrench in your field. If you make a good presentation and back it up with Code, they'll likely agree with your method.

Anthony

11/3/2025 09:42:18 am

I'd say it comes down to if there is an HOA. Though technically possible to run all units off a common system I would say its socially inadvisable unless there is a contractual agreement in place.

Tim link

11/3/2025 10:13:49 am

If they are set up so that the parcel could be subdivided into 3 separate parcels, they each have to have a separate system. During plan review, I always default toward subdivision because that's almost always how townhouses go.

Ivan J Humberson

11/3/2025 10:51:40 am

I agree with Tim's response - if the units are on separate properties, then you could not have one system feeding across property lines. That being said, I have seen several "townhouse condominium" projects wherein there was a common sprinkler system serving multiple townhomes. In my humble opinion, that is a horrible arrangement - if you have an incident in one townhome that requires shut-down of the sprinkler system, then all the other townhomes are shut down. In such a situation, a fire watch would normally be required until the fire protection system is back in service, but how do you do a fire watch for townhomes?? It's just not a good arrangement, and separate systems are a much better approach.

Jack G

11/3/2025 11:07:27 am

Check with the AHJ.
Near me —- each municipality requires a separate service for each address or a riser room commonly owned with 3 controls., fire meter, electric meters , domestic water meter etc.
probably for charges to each owner.

Todd E Wyatt

11/3/2025 12:42:10 pm

The first step is determining WHAT the scoping Code is for the Project …. IBC vs IRC?

IBC states “TOWNHOUSES not more than three stories above grade plane in height with a separate means of egress, and their accessory structures not more than three stories above grade plane in height, shall comply with this code (IBC) OR the International Residential Code” so the Design Team could use either IBC or IRC. Both Codes permit the use of NFPA 13D for TOWNHOUSES” that meet their definition (see REFERENCES below).

These (residential) automatic sprinkler systems (ASPS) can be designed as either stand-alone (separate) or multi-purpose (shared) systems. A stand-alone system uses its own dedicated piping exclusively for the sprinklers, whereas a multi-purpose system shares the same piping that supplies the home’s domestic plumbing fixtures. IRC-2024 P2904.3.3 Single Dwelling Limit includes the following, “… piping beyond the service valve located at the beginning of the water distribution system shall not serve more than one dwelling.”

Todd E Wyatt

11/3/2025 12:42:34 pm

REFERENCES

IBC-2024
Part 1 Scope and Application
Section 101 Scope and General Requirements
101.1 Title
101.2 Scope
The provisions of this code shall apply to the construction, alteration, relocation, enlargement, replacement, repair, equipment, use and occupancy, location, maintenance, removal and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures.
Exception: Detached one- and two-family dwellings and TOWNHOUSES not more than three stories above grade plane in height with a separate means of egress, and their accessory structures not more than three stories above grade plane in height, shall comply with this code or the International Residential Code.

Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.3 Installation Requirements
903.3.1 Standards
903.3.1.3 NFPA 13D Sprinkler Systems
Automatic sprinkler systems installed in one- and two-family dwellings; Group R-3; Group R-4, Condition 1; and TOWNHOUSES shall be permitted to be installed throughout in accordance with NFPA 13D.

Chapter 2 Definitions
TOWNHOUSES
A building that contains three or more attached townhouse units.
TOWNHOUSE Unit
A single-family dwelling unit in a townhouse that extends from the foundation to the roof and has a yard or public way on not fewer than two sides.

IRC-2024
Section R101 Scope and General Requirements
R101.2 Scope
The provisions of this code shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one- and two-family dwellings and TOWNHOUSES not more than three stories above grade plane in height with a separate means of egress and their accessory structures not more than three stories above grade plane in height.
Exception: The following shall be permitted to be constructed in accordance with this code where provided with an automatic sprinkler system complying with Section P2904:
1. Live/work units located in townhouses and complying with the requirements of Section 508.5 of the International Building Code.
2. Owner-occupied lodging houses with five or fewer guestrooms.
3. A care facility with five or fewer persons receiving custodial care within a dwelling unit.
4. A care facility with five or fewer persons receiving medical care within a dwelling unit.
5. A day care facility for five or fewer persons of any age receiving care within a dwelling unit.
Chapter 2 Definitions
BUILDING.
Any one- or two-family dwelling or TOWNHOUSE, or portion thereof, used or intended to be used for human habitation, for living, sleeping, cooking or eating purposes, or any combination thereof, or any accessory structure. For the definition applicable in Chapter 11, see Section N1101.6.
TOWNHOUSES
A building that contains three or more attached townhouse units.
TOWNHOUSE Unit
A single-family dwelling unit in a townhouse that extends from the foundation to the roof and has a yard or public way on not fewer than two sides.

Section P2904 Dwelling Unit Automatic Sprinkler Systems
P2904.1 General
The design and installation of automatic sprinkler systems shall be in accordance with NFPA 13D or Section P2904, which shall be considered to be equivalent to NFPA 13D. Partial automatic sprinkler systems shall be permitted to be installed only in buildings not required to be equipped with an automatic sprinkler system. Section P2904 shall apply to stand-alone and multipurpose wet-pipe sprinkler systems that do not include the use of antifreeze. A multipurpose automatic sprinkler system shall provide domestic water to both fire sprinklers and plumbing fixtures. A stand-alone automatic sprinkler system shall be separate and independent from the water distribution system. A backflow preventer shall not be required to separate an automatic sprinkler system from the water distribution system, provided that the sprinkler system complies with all of the following:
1. The system complies with NFPA 13D or Section P2904.
2. The piping material complies with Section P2906.
3. The system does not contain antifreeze.
4. The system does not have a fire department connection.
P2904.3 Sprinkler Piping System
P2904.3.3 Single Dwelling Limit
Piping beyond the service valve located at the beginning of the water distribution system shall not serve more than one dwelling.

Todd E Wyatt

11/3/2025 12:43:02 pm

Jack G

11/3/2025 07:39:29 pm

Disagree with a lot of the above. Towmships, municipalities have alternates, substitutions to IBC, IRC, IFC. Have their own versions.
First step is to find out what “they “ require “. The “letter “of the codes may not be required. First step, ask AHJ. Just saying.
Philadelphia, Delaware, Ben Salem, Trenton, Newark , Chester, LA, Chicago, Maryland( different by each county) .
Just as examples.

Jack G

11/3/2025 07:44:15 pm

And the outcome, when you ask the AHJ, could be there are amendments to follow, or code has not been amended, and they will list the code to follow…. to the letter.

chad

11/4/2025 12:00:19 pm

As most said, it depends. Some water departments/authorities will allow one connection to their system for the whole building's sprinkler, others want each unit separate if they are condo'ed. but if one owner, one system is ok.

Some water departments will allow 13D systems to be off the domestic. Some require sprinkler to be separate (I disagree with that).

From a life safety perspective, each should have its own flow, tamper and be monitored, IMO. That way you can isolate one unit and protect the rest.

Curtis Tower

11/4/2025 05:29:17 pm

When considerint arrangements such as this, I look at who is responsible for the fire sprinkler system over the life of the system/building. When townhomes are separately occupied, perhaps owned by different people, then I always lean toward individual systems. This negates the issue of one person being responsible for a single riser supplying an entire building and protecdting multiple families.

Now, if there is an HOA or managing entity that collects fees on a monthly or annual basis for caring for the common appurtenances, then a safe argument can be made for a single riser...but that has its risks, as well. HOA/BA's aren't always stable or responsible.

Just some food for thought, though I would still lean toward individual systems.

Each Townhouse Have Its Own NFPA 13D System?

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