Description: The question is about the NFPA 13 guidelines for making sprinkler systems in a structure with more than one floor. It asks if one main control valve can provide water to all the floors of a building, such a flat with four floors. It also checks to see if the total area covered can go beyond a particular limit, as long as each floor stays within the permissible amount. 

Question 1.  Does the 2022 version of NFPA 13 enable a multi-story building (such as a four-story apartment) to be supplied by a single control valve? If so, can the total system area exceed 52,000 square feet as long as no individual floor exceeds 52,000 square feet, as per Section 4.4.1(1)? 

Ans. No. Section 16.9.10 of the 2022 edition of NFPA 13 requires that all multi-story buildings (greater than two storeys) include a floor control valve for each floor level (see 16.9.10.1).

The few exceptions to this criterion are listed below:

• The top floor does not require a floor control valve because the sprinklers are fed from the floor below (Section 16.9.10.2).
• Floor control valves are not necessary if the total area of all floors does not exceed the system area limits outlined in Section 4.1 (16.9.10.3).
• Dry systems in parking garages do not require floor control valve assemblies (Section 16.9.10.4).

Based on these rules, it is not intended to allow a multistory building to be served by a single floor control valve assembly, unless the exception in Section 16.9.10.3 applies. This exception allows for a single control valve only when the total area of all floors does not exceed 52,000 square feet, assuming a mild or ordinary hazard classification.

This exception prevents the entire system size from exceeding 52,000 square feet simply because no single floor exceeds that limit.

If the total aggregate size of all floors in the building (e.g., a four-story apartment) does not exceed 52,000 square feet, Section 16.9.10.3 allows a single control valve to serve the whole structure. Assuming equal size, each floor would be limited to 13,000 square feet (4 x 13,000 = 52,000 square feet). 

Description: This question is about how to use some of NFPA 13’s regulations for designing sprinklers. It asks if other regulations concerning not blocking the spray from sprinklers still need to be observed even when tiny changes in ceiling height are viewed as a level ceiling. To put it simply, it’s checking to see if designers still need to think about anything that could stop the flow of water, even when the sprinklers are spaced out evenly. 

Question 2.  Can you confirm that while applying the vertical change in elevation less than 36 inches rule, Section 10.2.6.1.1(B) in the 2019 edition of NFPA 13, the other obstruction regulations, such as sprinkler placement to avoid obstructions to discharge in Table 10.2.7.1.2, still apply? I believe there is a widespread misperception that because sprinklers may be spaced as if the ceiling is flat, there is no need to address blockage. 

Ans. Yes, the obstruction restrictions continue to apply when using NFPA 13, 2019 version, Section 10.2.6.1.1.3 (B).

This section discusses the deflector distance for normal spray upright and pendant sprinklers. Section 10.2.6.1.1.3 states that the standards of Section 10.2.6.1.1.1 do not apply to light and ordinary hazard occupancies with ceilings of noncombustible or limited-combustible construction when either Section 10.2.6.1.1.3(A) or Section 10.2.6.1.1.3(B) apply.

Section 10.2.6.1.1.3(B) states that if the distance between the upper ceiling and the sprinkler deflector is less than or equal to 36 inches, the sprinklers may be spaced as if the ceiling were flat, provided the obstruction rules are followed, as shown in Figure 10.2.6.1.1.3(B). This part requires the obstacle rules to be followed. 

Description: This question is about what kind of material is utilised for the pipes that come after the main drain valve in a system. It wants to know if the pipe has to be made of steel or if plastic pipes like CPVC or Schedule 40 PVC are okay. In short, it’s about making sure that the pipe material is right for that section of the system. 

Question 3.  Is steel required for discharge piping downstream of the main drain valve, or can CPVC or Schedule 40 PVC be used instead? 

Ans. No, plumbing downstream of the main drain valve does not have to be steel.

NFPA 13 does not specify a particular material for main drain discharge piping. Section 6.1 discusses listing requirements, with Section 6.1.1.2 demanding the listing of components critical to system performance unless otherwise permitted. However, Section 6.1.1.5 states that components that do not affect system function, such as drain pipework and valves, are not required to be included.

Because main drain piping just transports discharged water away from the building and has no effect on system hydraulics or operation, it does not need to be steel or a listed material. 

Description: This question is about how to do a hydrostatic test on the suction piping that takes water from a storage tank to a fire pump. It wants to know if the test can be done at the tank’s lower pressure or if a higher standard test pressure (200 psi) is needed. To put it simply, it’s checking what level of pressure is needed to safely test that section of the fire prevention system. 

Question 4.  What are the hydrostatic testing requirements for suction pipework when supplying a fire pump from a water storage tank? Because the fire department connection (FDC) is on the discharge side, can the suction piping be hydrostatically tested at the tank pressure, or must a test pressure of 200 psi be used? 

Ans. The hydrostatic test requirement for a suction pipe taking water from a tank is either 200 psi or 50 psi greater than the system’s maximum pressure. This criterion is outlined in Section 14.1.2.1 of the NFPA 20, 2025 version.

This provision expressly indicates that this rule applies to both suction and discharge pipes, and there is no “exception” for suction pipe fed by a tank, therefore it would apply to the circumstance stated. 

Description: This inquiry is about when to check several wet pipe sprinkler systems in a building. It wants to know if the internal inspection (assessment) may be split up, with half of the systems being checked after 5 years and the other half after 10 years. In simple terms, it’s trying to figure out if inspections may be done at different times instead of all at once. 

Question 5.  In buildings with multiple wet pipe sprinkler systems, is it permissible to do the mandatory internal assessment on one-half of the systems five years after installation and the remaining systems ten years after installation?

Ans. Yes. When doing an internal examination of wet pipe sprinkler systems, NFPA 25, Section 14.2.2 allows every other wet pipe system to be internally assessed every five years. This provision only applies to wet pipe systems; all other system types (such as dry pipe) require an internal assessment of each system every five years.

NFPA 25 timeframes begin on the date the system is put into operation, which is usually the same as when the certificate of occupancy is issued. For instance, in a structure with ten wet pipe systems and two dry pipe systems:

• At five years, evaluate five of the ten wet pipe systems and both dry pipe systems.
• At ten years, evaluate the remaining five wet pipe systems and both dry pipe systems again.

The exception is that if obstructive foreign material is discovered during the assessment of the selected wet pipe systems and potentially degrades system performance, all wet pipe systems must be internally inspected at that time, independent of the alternating schedule.

Description: NFPA 13’s 2022 version employs the phrase “stockpiles.” For example, Section 4.3.3.1 defines an ordinary hazard, Group 1 occupation as having “stockpiles” that do not exceed 8 feet.

When a term is not defined in Chapter 3, I understand that the Merriam-Webster Collegiate Dictionary’s standard definitions are utilised. However, in this instance, the dictionary defines stockpiles as “a storage pile.” This concept does not distinguish between a stockpile and storage. 

Question 6.  What is the distinction between storage and stockpiles, as defined by NFPA 13.?

Ans. You are correct that when a term is not clearly defined in Chapter 3 of NFPA 13, the 11th edition of Merriam-Webster’s Collegiate Dictionary is used to determine the commonly accepted definition of the term.

In this example, the lexicon does not provide a clear definition of what NFPA 13 intends by the term stockpiling. However, Annex Section A.4.3.3 may be helpful. This section describes:

“…Stockpiles are considered to include display merchandise (e.g., mercantile stockpiles) and arrangements of combustibles ancillary to operations within the occupancy as opposed to dedicated storage areas where the fire loading is generally more severe.” 

Description: A building has a big noncombustible trellis that is otherwise open to the elements. Sprinklers are required beneath this trellis due to the likelihood of combustibles being stored there, according to Section 9.2.3.4 of the 2022 version of NFPA 13.

According to Annex A.9.2.3, sprinklers should not be required beneath trellis overhangs or other similar structures that cannot absorb heat to facilitate sprinkler performance. In this situation, the trellis is predicted to be more than 75% open, and it is unlikely that the structural parts will absorb enough heat to trigger sprinklers. 

Question 7.  Is sprinkler protection essential in this scenario? 

Ans. Fire sprinklers require a ceiling or “lid” on their upper surface to absorb heat and activate them. Heat collection and fire sprinkler activation are often not possible when there is no ceiling or the ceiling is mostly open to the sky above. This is clearly stated in Annex A.9.2.3: “Sprinklers should not be required beneath trellis overhangs or similar construction that is incapable of collecting heat to aid in the operation of the sprinkler.”

Additionally, Section 9.2.3.4 applies to exterior projections. Based on the definition in Section 3.3.73, this Trellis is not an outside projection, hence Section 9.2.3.4 does not apply.

Exterior projections are defined as extensions of the exterior wall that are “capable of collecting heat below.” This criterion, which is new in the 2022 edition, was added in part to omit features like trellis that do not have an above surface to collect heat.

Based on this phrase, NFPA 13 does not plan to provide sprinkler protection in areas where the sprinkler is unlikely to operate. 

Description: In Section 12.6.4 of the 2016 version of NFPA 13, an exception allows variation from the minimum K-factor standards mentioned in the previous two sections when altering an existing system.

In the 2019 edition of NFPA 13, this content was reorganised into Section 21.1.5, however the explicit reference to the previous minimum K-factor sections was eliminated. 

Question 8.  Is there still a comparable allowance for existing systems in the 2019 version, or was this exception removed on purpose? 

Ans. The 2019 edition of NFPA 13 contains a similar exclusion, which has been moved to Chapter 29, Existing System Modifications.

The 2019 edition underwent considerable reorganisation, with rules pertaining to the modification of existing systems being relocated to a new chapter, Chapter 29, named “Existing Systems Modifications.”

The idea originally found in Section 12.6.4 of the 2016 version of NFPA 13 is now included in Section 29.1.5 of the 2019 edition. 

Description: When testing NFPA 13-compliant systems, NFPA 13E specifies delivering 150 psi to the fire department connection (FDC).

How should this be used in systems designed according to NFPA 13R? Some argue that NFPA 13R systems should only be evaluated at a pressure equal to the available municipal water supply, rather than 150 psi. 

Question 9.  Is there any guidance or explanation for limiting the test pressure for NFPA 13R systems, or should the 150 psi test pressure still be used? 

Ans. NFPA 13E is the recommended standard for fire department operations using sprinklers and standpipes. It recommends 150 psi regardless of whether the piping is metallic or nonmetallic.

A 200 psi hydrotest is required during installation for both NFPA 13 systems (commercial building sprinkler systems with metallic piping) and NFPA 13R systems (residential sprinkler systems with nonmetallic plumbing). The plastic pipework is designed and tested to resist pressures more than 150 psi.

CPVC pipe, designated for fire protection, is rated for a pressure of 175 psi (like most steel pipe).

Indeed, NFPA 13R stipulates that “When nonmetallic pipe is used, the pipe shall be designed to withstand a working pressure of not less than 175 psi at 120°F.”

Description: Sprinklers may be removed from closets in hospital rooms measuring no more than 6 square feet, according to the 2019 version of NFPA 13. 

Question 10.  Can this omission apply if the sprinkler in the patient room is subject to the small room rule and is less than 9 feet from the back wall of the closet? 

Ans. Yes. According to NFPA 13, 2019 edition, Section 9.2.5 for hospital clothes closets, sprinklers are not required in clothes closets of patient sleeping rooms in hospitals where the closet area does not exceed 6 square feet, as long as the distance from the sprinkler in the patient sleeping room to the back wall of the closet does not exceed the maximum distance permitted by Section 9.5.3.2.

Section 9.5.3.2 discusses the maximum distance from walls. The space between sprinklers and walls must not exceed one-half of the maximum distance between sprinklers. Section 9.5.3.1.3 states that the maximum distance authorised between sprinklers must be in accordance with the value specified in the corresponding section for each kind or style sprinkler.

Assuming you are utilising standard spray sprinklers, Section 10.2.5.2.3 for standard spray sprinkler spacing states that the requirements of Section 10.2.5.2.1 do not apply to tiny rooms as stated in Section 3.3.196. According to Section 10.2.5.2.3.1, sprinklers may be installed no more than 9 feet from any single wall.

In your case, if you have a hospital clothes closet that is less than 6 square feet and is in a room that meets the definition of a small room, and you are using standard spray sprinklers, the sprinkler can be spaced up to 9 feet from the back wall of the closet, and the sprinkler in the closet can be removed.

Description: According to Section 7.2.6.3.1 of the 2013 edition of NFPA 13, the compressed air supply for a dry pipe system must come from an always-on source. 

Question 11.  Does a compressor plugged into a circuit shared with other outlets or equipment meet this requirement? 

Ans. Because the applicable standard is the 2013 edition of NFPA 13, there is no specific ban on utilising a compressor driven via a cord and plug connection.

However, this strategy is not regarded as best practice since it raises the danger of unintentional power loss to the compressor and the accompanying operational concerns that may arise.

A better installation method is to hardwire the compressor to the power source.

Beginning with the 2019 version of NFPA 13, the committee decided that cord-and-plug-connected compressors are unacceptable. This edition includes specific precautions. Section 8.2.6.6.5 mandates that air compressors used for the dedicated air supply be installed in compliance with NFPA 70 (Article 430).

Furthermore, Section 8.2.6.6.5.1 says that a dedicated compressor cannot be plugged into a wall socket or connected to a light switch. These restrictions are designed to decrease the number of false trips caused by the compressor being accidentally turned off or unplugged.

Additionally, beginning with the 2025 edition, air compressors used as the dedicated air source for dry pipe systems must be listed for fire sprinkler application.

Description: This question is about how to use NFPA 13 to help you design sprinklers for a home. It wonders if a certain Annex section can be used to avoid putting in sprinklers in closets that are less than 12 square feet. It also points out a problem: the local authority (AHJ) claims that Annex parts are merely suggestions, not requirements that must be followed. This means that sprinklers may still be needed. 

Question 12.  Can Annex D, Section D.1.1.6.1 of the NFPA 13 residential design for a new apartment building be utilised to exclude sprinklers in closets smaller than 12 square feet?

An Authority Having Jurisdiction (AHJ) stated on a recent project that Annex rules are not enforceable requirements and, as a result, sprinklers must be put in these closets. 

Ans.  No. NFPA 13, 2016 edition, Annex D (containing Section D.1.1.6.1) should not be used to justify installing sprinklers in closets less than 12 square feet in a new apartment building. NFPA 13 mandates sprinklers in all apartment living unit closets, regardless of size. The “12 sq ft” notion originated in NFPA 101 and was moved to Annex D to minimise misunderstanding.

Annex D is informational and does not create NFPA 13-compliant omission criteria.

NFPA 13’s objective for apartment occupants is to require sprinklers in closets. According to consistent interpretations, sprinklers must be installed in all apartment housing unit closets, regardless of size.

The limited “small closet omission” in NFPA 13 only applies to hotels and motels. Sprinklers may be deleted from small closets in those occupancies, according to Section 8.15.8.2, however sprinklers are necessary in apartment buildings because they are neither hotels or motels.

As a result, the AHJ’s opinion that Annex D is not enforceable is consistent with its original purpose as instructional material and does not supersede the installation requirements of NFPA 13 for apartment closets.

If the jurisdiction has accepted NFPA 101, it might be argued that the closest exemption in Section D.1.1.6.1 applies, as a code may replace a standard based on local adoption and enforcement.