Summary: This collection of frequently asked questions (FAQs) addresses a wide range of fire prevention system and building code issues. The scenarios include post-fire sprinkler system testing, canopy materials, and concealed areas with composite wood joists. Notable points include the contrast between membrane and through penetrations in fire-rated structures, the need for sprinkler protection in greenhouses near educational establishments, and water delivery time concerns in a dry pipe system for idle wood pallet storage. 

The responses consistently refer to relevant codes, including NFPA 13 and the International Building Code, to ensure compliance and safety. These FAQs are a helpful resource for professionals interested in fire protection engineering since they highlight the complex considerations in many scenarios while emphasising the need to adhere to code standards for successful fire safety measures.

#1. Through vs Membrane Penetrations Description- A sprinkler drop penetrates a two-hour-rated ceiling assembly made of metal channels sandwiched between four layers of drywall. Question 1. Is it necessary to plug this breach with fireproof material?

Answer. The answer depends on whether the penetration is through the membrane or not. Section 714.5 of the 2018 International Building Code (IBC) specifies the difference between through and membrane penetrations for horizontal structures such as floor ceilings, as established in Chapter 2.

A membrane penetration is a single breach in the floor-ceiling assembly, while a thorough penetration is a rupture on both sides. Regarding horizontal assemblies (floor/ceiling):

  • Section 714.5.2 specifies membrane penetration standards, with exception 5 allowing for the annular area generated by a fire sprinkler with a metal escutcheon without requiring fire stopping.
  • Section 714.5.1 specifies the criteria for through penetrations, including fire-stopping.

#2. Mezzanine Level and Standpipe Requirements Description- The project is a three-story building with a mezzanine that is higher than the 30 feet threshold. The floor level of the uppermost floor is less than 30 feet above the level of fire department entry. Section 505.2 of the 2021 edition of the International Building Code (IBC) says that this mezzanine meets the standards. When the highest story is more than 30 feet above the lowest level where the fire department can get to it, the IBC says that standpipes must be installed. Question 2. Since the mezzanine level is 30 feet above where the fire department can get to it, do we need a standpipe system?

Answer.The mezzanine in your case is not considered an independent story and does not meet the height criteria required by IBC, Section 905 for a standpipe system.

IBC Section 505 defines a single mezzanine as part of the level below, not a separate story or occupiable floor.

According to 905.3.1, a standpipe is only required for buildings with four or more stories or an occupiable floor 30 feet above or below the level of fire department truck access.

The 2021 IBC defines a mezzanine as an intermediary level between the floor and ceiling of a story, in accordance with Section 505.

The 2021 IBC defines a mezzanine as an intermediary level between the floor and ceiling of a story, in accordance with Section 505.

#3. Two Buildings served by a Single Remote Fire Department Connection Description- A project involves adding a new building to an already-spread lot. The original building has an underground fire main and a remote fire department connection (FDC). The suggested solution involves connecting the new building to the existing underground fire main via a new lead-in and using the existing FDC. Although NFPA 13 and NFPA 24 permit a single FDC to serve multiple systems, the authority having jurisdiction (AHJ) is concerned about isolating each building, which necessitates turning off the water at the fire riser. Question 3. Is it permitted to service two buildings with a single remote FDC?

Answer.  NFPA 13 and NFPA 24 allow for a single fire department connection to serve fire sprinkler systems across several buildings. Sprinkler systems are thought to protect against single fires. The guideline does not address defending against numerous fires simultaneously.

According to the 2016 edition of NFPA 13, a remote FDC can service several systems (Sections According to Section, for multiple systems, the FDC must be linked to both the supply and system control valves. Section clarifies that the criteria for multiple systems do not apply if the FDC is linked to subsurface plumbing.

The appropriate document for connecting the FDC to the subsurface is NFPA 24.

The 2016 edition of NFPA 24, Section 5.9, covers distant fire department connections. Section discusses the concept of a distant FDC that serves many buildings. This clause requires an FDC to provide a sign specifying which buildings it serves.

The use of a remote FDC requires approval from the AHJ, as per NFPA 24. According to NFPA 13, Section, the FDC must be located near a fire department or at a location approved by the authority having jurisdiction.

To charge the FDC in the event of a fire in another building, there is no need to isolate one building by shutting down water at its fire riser. The non-fire building’s closed sprinkler system will not be affected by greater pressure from the FDC due to its inactivity.

According to NFPA 13, Section A.17.2.3, the function of a sprinkler system’s FDC is to supplement pressure, not to deliver specific flow or meet system demands.

#4. Fire Alarm required for a NFPA 13D System Description- NFPA 13D systems do not require fire alarms. Local waterflow devices are necessary for residences without smoke alarms or detectors, according to Section 7.6 of the 2016 NFPA 13D. While smoke alarms are required in residential construction, NFPA 13D rarely specifies a local alarm, emphasising cost-effectiveness and flexibility in compliance. Specific criteria may differ depending on contractual agreements or local restrictions. Question 4. Is a fire alarm necessary when installing an NFPA 13D fire sprinkler in a one- or two-family home?

Answer: No, NFPA 13D sprinkler systems do not require a fire alarm system. According to Section 7.6 of the 2016 version of NFPA 13D, residences without smoke alarms or detectors must install local waterflow devices, which are not considered fire alarms. This section’s appendix clarifies that the described local waterflow alarm is neither a listed fire alarm nor connected to a central station or fire alarm system.

Residential construction rules and NFPA 13D require smoke alarms to be installed in all residences. According to Section 4.4 of the 2016 edition of NFPA 13D, smoke alarms must meet NFPA 72 standards. As all residences are required to have smoke alarms, NFPA 13D rarely requires a local alarm.

This is not to suggest that a local alarm or even a fire alarm is not acceptable; nonetheless, they are not necessary.

NFPA 13D encourages cost-effectiveness and does not require their usage.

It’s important to note that NFPA 13D systems may require a local waterflow or fire alarm, depending on the contract or municipal law.

#5. Area Limitations and the Total Square Footage of a 2-story Building Description- The project includes a two-story building with a total square footage of 56,000 square feet. The first story is 46,000 square feet, while the second floor is 10,000 square feet. The building is categorized as a light hazard occupation. Question 5. Is it possible to protect this building with a single sprinkler system, and do floor control valve assemblies meet NFPA 13 requirements for 2019?

Answer:  Yes, the two-story building indicated above can be protected with a single sprinkler system.

According to Section 4.5.1 of the System Protection Area Limitations, a single sprinkler system riser cannot cover more than 52,000 square feet of floor space for a light or ordinary hazard occupancy.

The expression “on any one floor” refers to the maximum area of a single floor, not the total area of all floors.

A single sprinkler system is authorized in this scenario since no floor exceeds 52,000 square feet.

Section only requires floor control valve assemblies for multistory buildings over two floors in height; hence, floor control valve assemblies are not necessary.

#6. Greenhouse Sprinklers Description- The need for a fire alarm while installing an NFPA 13D fire sprinkler system in a one- or two-family home. The answer indicates that NFPA 13D systems do not require a fire alarm. Local waterflow devices are necessary for residences without smoke alarms or detectors, according to Section 7.6 of the 2016 NFPA 13D. Question 6. Are sprinklers essential in a permanent greenhouse adjacent to an educational facility?

Ans. Yes, the greenhouse must be sprinkler-protected. This assumes the existing educational building has sprinkler protection and the greenhouse extension is not considered a distinct building per code.

The International Building Code (IBC) and NFPA 13 do not allow for the omission of sprinkler protection when adding a greenhouse to an existing building with sprinklers. According to NFPA 13, 2022 edition, Section 4.1.1, buildings with automatic sprinkler systems must have sprinklers in all areas, unless specified otherwise. NFPA 13 prohibits omitting sprinklers from greenhouses.

If the greenhouse is a distinct building, automatic sprinkler protection may be required under IBC Chapter 9 and Section 903.

#7. Idle Wood Pallet Storage - Dry Pipe System Water Delivery Description- A dry pipe sprinkler system is used to protect a cold dock in line with NFPA 13 (2016). The water supply time is determined using a listed program and must align with Table The table shows the maximum calculated water supply times for light, regular, additional, and high-piled storage. There is a single rack that will hold up to 11 feet of idle wood pallets. Question 7. Given that this does not fit the definition of high-piled storage, what is the maximum water delivery time from Table

Answer: The maximum water delivery time would be 40 seconds if all four remote sprinklers were open.

Table provides water supply times based on protective requirements, with shorter times as the hazard level increases.

Idle pallet storage 12 feet high does not match the definition of high-piled storage, which is defined as storage over 12 feet high. However, the parameters for idle pallet storage align with general storage requirements.

Idle pallet storage is dangerous as it generates great heat and quickly spreads flames during a fire. Pallet storage design requirements can lead to increased flow compared to high-piled commodity storage, such as Group A polymers. To achieve high-piled storage requirements, the delivery time for idle pallets must be minimal.

#8. Minimum Required Discharge for Small Buildings Description- The project includes an 800 square foot stand-alone building with non-rated walls and an extra hazard sprinkler system that meets the 2022 version of NFPA 13. The standards of and are appropriate for a small section of higher hazard occupancy within a larger lower hazard facility. The high hazard occupancy can be increased in the future, and the additional flow allows for system adjustments. When applied to a small building with high hazard occupancy, has a considerable impact on hydraulics. Question 8. Is the additional flow from Section necessary for the hydraulic calculations of this little isolated building?

Ans. NFPA 13 provides two options for avoiding the increased flow required by This additional flow is commonly referred to as phantom flow.

To calculate sprinklers within an 800 square foot building, apply the density area approach and adhere to requirements. To proceed, obtain agreement from the authority having jurisdiction (AHJ) that Section does not apply to this building due to its small size and lack of additional sprinkler flow requirements. The annex note A. (which described the method for adding the flow required by was relocated to A. during the first draft of the 2025 edition of the standard (see FR-1254). This action indicates that the committee believes these are separate ideas and may support your case when discussing them with the AHJ. The language used in these sections may make it difficult to sell. If the building or sprinkler system is expanded in the future, permits and proof of hydraulic capacity are required to protect the additional area.

The second option would be to use the room design process. Since is in the Density/Area Technique section, it is not applicable to the room design method. Although the stand-alone building has non-rated walls, the room design approach does not require outside walls to be fire-resistant. According to Section, “all interior walls enclosing the room shall have a fire resistance rating equal to the water supply duration.”

The outer walls do not need to be rated, and the charging statement in Section applies to the room design technique. This section states that water delivery needs for sprinklers should be based on the room with the highest demand.

#9. Testing After Replacing Sprinkler Due to Fire Description- Following a fire in a sprinklered structure that activated ten sprinklers, the answer mentions the 2020 version of NFPA 25, which states that when replacing sprinklers, leaks must be inspected at the system's working pressure. Question 9. A fire erupted in a sprinklered building, activating 10 sprinklers that required replacement. What pressure is required to test the sprinkler system after replacement?

Answer: System working pressure. This is based on the terminology given in the NFPA 25, 2020 version. According to Table 5.5.1, when replacing “Sprinklers, regardless of number,” the mandatory action is to inspect for leaks at the system working pressure. If repairing or replacing pipe and fittings affects 20 or fewer sprinklers, the piping systems must be evaluated for leaks at system working pressure, according to the table. If more than 20 sprinklers are impacted, a hydrostatic test under NFPA 13 is required.

Section 29.7 of the NFPA 13 2019 version lends support to this idea. This section covers changes to existing systems and piping, not sprinkler replacement. However, it does state:

  • 29.7.1 – Modification of existing piping systems tested at system working pressure.
  • part 29.7.2 requires testing at 200 psi for 2 hours when more than 20 sprinklers are affected. However, this part does not apply to this project as it only involves 10 sprinklers.
  • 29.7.3- When modifications cannot be separated, test at system working pressure. This section applies to replacing sprinklers on an existing system, as they cannot be isolated.

In Annex A.5.2 of NFPA 25 (2020), there are suggestions for coping with post-fire issues. This appendix section suggests:

  • Inspect all sprinklers in the fire area.
  • For small fires (managed by one or two sprinklers), replacing only the activated sprinkler may suffice.
  • Soot-covered sprinklers should be replaced.

In the event of a significant fire, it may be necessary to replace the first ring of sprinklers encircling two operational sprinklers due to heat damage to the reaction mechanism.

The annex section is not part of the standard’s criteria, so site-specific conditions must be considered.

#10. Vertical Openings Description- A fully sprinklered building has an entrance that connects the first and second floors exclusively. According to Section 712.9 of the 2015 International Building Code, this two-story aperture does not require an enclosure. Question 10. Is it necessary to have closely spaced sprinklers and draft stops as per Section 8.15.4 of NFPA 13 (2013)?

Answer: According to Section, sprinklers and draft stops must be closely spaced for unenclosed openings where sprinkler protection is used as an alternative to vertical enclosure. Section does not apply to this opening since it is not required to be enclosed under Section 719.1.9.

#11. Non-Combustible Canopy with Combustible Finish Description- A 6-foot-wide outer canopy is made of non-combustible materials. The canopy's bottom side features a 3/4 inch deep non-structural tongue and groove cedar finish. According to Section of the 2010 edition of NFPA 13, sprinklers can be removed from noncombustible exterior projections. Question 11. Can sprinklers be removed from under this canopy?

Answer. Sprinklers cannot be omitted beneath the canopy indicated.

Sprinklers are not required for canopies, roofs, porte-cocheres, balconies, decks, or similar projections made of non-combustible, limited-combustible, or fire retardant-treated wood, as defined in NFPA 703, Standard for Fire Retardant-Treated Wood and Fire-Retardant Coatings for Building Materials. This is according to Section of the 2010 edition of NFPA 13.

The need for noncombustible materials extends beyond structural members to include the canopy finish.

#12. Concealed Space with Composite Wood Joists Description- According to Section of the 2016 edition of NFPA 13, sprinklers can be skipped in concealed spaces made of composite wood joists and a gypsum board ceiling, as long as the joist channels are fire-stopped in 160 cubic feet. Question 12. Is it necessary to place firestoppers perpendicular to composite wood joists, or may the joists be ``sheathed`` to avoid using sprinklers?

Answer: To avoid sprinkler protection under Section, joist channels must be fire-stopped with materials similar to the composite wood joist’s web construction.

To prevent fires from spreading into the joist channel, the material should be placed perpendicular to it. This piece can be applied without sheathing the full composite wood joist. This is obvious from the necessity to utilize a “material equivalent to the web construction.”

For ceilings fitted with metal channels (1 inch max), 3 1/2 inch batt insulation should be put at the bottom of joist panels. only addresses whether sprinklers can be omitted from a combustible concealed compartment. Section should also be addressed. The nearby area for sprinkler operation must be 3,000 square feet, unless an exception is granted (see

Section is not about omitting sprinklers but rather about compensating for probable fires in exposed spaces. If a fire is not controlled in the unprotected space, a larger design area is required to compensate for the larger fire that may break through to a sprinklered area.

To avoid extending the design area, the conditions are more severe. According to Section, composite wood joist construction requires “adjacent joist channels” to be fire-stopped in quantities of no more than 160 cubic feet, using materials equivalent to 1/2 inch gypsum board.

This varies from the criteria of in two ways:

  1. According to, firestop materials must be similar to web construction, although specifies that they should be equivalent to 1/2 inch gypsum board.
  2. According to, individual joist channels must be fire-stopped to a volume of 160 cubic feet. However, requires “adjacent joist channels” to be fire-stopped to a volume of 160 cubic feet, which may necessitate installing fire-stopping between channels.

Courtesy: Roland Asp, CET, TechNote 507