I’m wondering if you can help me on this one.

​I have a project with the detail below referencing the use of the U419 listed assembly, but with the drywall only on one side of the assembly. 

I asked for verification that the U419 assembly would permit this and he provided me with the attachment referencing section 5A. I don’t believe that was the intent for section 5A of the listing, but I can’t figure out what the actual intent is.

Is drywall on only one side of the assembly here correct?

Is it allowed anywhere?

It is something that has come up since there is a V497 listed assembly that puts both layers of drywall on one side of the wall, but my understanding has always been that it was used only on the interior side of exterior walls required only to be rated from the inside (IBC Section 705.5).

Any assistance would be greatly appreciated. I appreciate your help.

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We have a showroom with an open mezzanine that takes up around 30% of the floor area. The bottom and the top of the mezzanine are office areas. The showroom has a ceiling height of 23-ft while the mezzanine has a ceiling height of 11-ft.

We designed the the showroom as Ordinary Hazard using standard response, extended coverage sprinklers (18' x 18') on the ceiling with the top part of the mezzanine also being protected with standard response, extended coverage. There are no walls on the top side of mezzanine.

On the flip side, we designed the bottom part of the mezzanine using Quick Response, Light Hazard (15' x 15' ) spacing since it's an office (Light Hazard occupancy).

However, since this is an open mezzanine with no walls separating between the two spaces, this means that both these areas would be considered one compartment. Under NFPA 13, sprinklers in the same compartment should be the same response type and hazard levels.

However, would the elevation difference and the mezzanine floor separating the two make it okay to have two different type of hazard level and response type?

If not, what about adding draft curtains?

Thanks in advance.

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We have a tree, wet system, we are using Schedule 7 for the mains and branch lines.

We are trying to design the seismic bracing, and the main is only strong enough for one side of branch lines, not the opposite side too.

Should we use stronger pipe, or install more laterals?

Is there a way to brace the branch lines to take the weight off the mains?

Thanks in advance.

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What is the difference between feed main and cross-main in a sprinkler system?

As NFPA 13 mentions, feed main supplies the cross mains but in tree sometimes main pipe continues and supply the branches.

What's the difference?

Are we talking about each individual piece of pipe?

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Would it be possible to replace a Kennedy K-10 dry barrel fire hydrant with a wet barrel fire hydrant if the main valve of the K-10 was left open, and a wet barrel hydrant was then bolted to the standpipe base?

We're in southern California, so we commonly have wet barrel hydrants in the area. Replacing with a wet barrel means we wouldn't have to excavate. 

The main reason I see is that the drain holes would be left open if the dry barrel main valve is removed. We have been unable to find new main valves for Kennedy K-10 hydrants. Your comments would be greatly appreciated.

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I have a dining room in a clubhouse that has multiple ceiling pockets at different sizes that are 1-5" in depth.

The total cubic footage of these pockets is 1,165 cubic feet.

Could I protect one of the pockets in this space to bring my total unprotected pockets under 1,000 cubic feet, and leave the rest of these pockets unprotected?

The entire floor space in this area will be protected.

Thanks in advance.

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I have a K14 ESFR system in a tall building; 45-ft peak and 35-ft eaves, that was hit by the changes in NFPA 13 and there is now a recommendation to upgrade protection to K25 ESFR sprinklers due to the roof height.

The current design is a very strong 12 K14 @ 90 psi and the storage is low at 16-ft of palletized Class III and IV goods.

Based on the current storage arrangement, 2022 NFPA 13 allows for either K25 ESFR system or a CDMA design of .64/2,000 using ordinary temperature sprinklers.

Is is permissible to recalculate ESFR systems with a CDMA design?

If so, is there any specific mention or directive in code?

I am not a designer but back of napkin math indicates I have a 1.33 gpm/sqft. density over the first 1,200 sqft based on the ESFR design and probably a .80/2,000.

Thanks in advance.

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Can all main drains can be joined in one pipe?

If they can, does this pipe need to be capable of handling all flow at the same time?

Are there any downsides to ganging them together?

Thanks in advance.

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Where would I go to find CMDA protection of Rack Storage less than 12-ft?

In this particular case, I'm looking at Class III commodities on wire racks in a 2,000 sqft room with 8-ft ceilings. This is paper file storage.

In the past, I have been able to use the miscellaneous storage requirements, but not this time.

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We have a car park area which is part of a bigger development that we are sub-dividing into different pressure zones due to it being a very tall building. The three levels of car park in total are less than 65-ft (20 m) high, but they are very long and wide. My question is about sprinkler control valve areas.

I know for ordinary hazard the restriction per floor from one riser is 52,000 sqft (4830 sqm) with no restriction as you go up.

Does that mean for a wide, low-level building, say on 1 level, do we need a system riser for each 52,000 sqft?

This seems pretty onerous to me, as FM Global do not even insist on this. Here in England, the restriction is 12,000 sqm x 10 floors per valve.

I'm being asked by the authorities to allow the valves, but is that restriction of 52,000 sqft (4830 sqm) per valve set on a single floor set in stone?

Can we do something based on hydraulic calculation that is more user friendly?

Thanks in advance.

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Does NFPA 13 address the ability to size sprinkler pipe simply by being "sized by similarity"?

For instance, I have a small room that has (4) 1/2" pendent sprinklers to be located in it. I cannot determine any pipe routing from above due to an old ceiling but can verify the lines are 1-1/2" schedule 40.

I've heard of this method being used but do not find it in NFPA 13 so I'm hesitant to use this method.

Thanks in advance.

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Is there a room volume cut off that you use for clean agent space to make sure that your system will pass the room integrity fan test?

As an extreme example, a 50,000 sf space would probably be better for something like a double interlock preaction system since it would be difficult to make sure that the space is of tight enough construction to hold the clean agent (there will inherently be some leaks in construction despite doing all the recommended practices of gasketing, door threshold blocking, etc).

Thanks in advance!

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For a project that has seismic expansions and the fire sprinkler piping is predominately CPVC, are seismic loops or assemblies still required?

If so, is there are preferred installation method?

Would we need to transition to steel, then back to CPVC, in order to install a Metraflex or similar product?

Thanks in advance.

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Fire alarm question for an ICC state that adopts 2012 IBC/IFC & NFPA 72, 2010 edition.

I have an existing mixed use F-1 & S-1 occupancy. This building was originally built in 1910 with two additions over the years. The building sustained fire damage a year ago and is undergoing repairs, no additions, just repairing fire damage that was quite extensive.

The building is not sprinkled (not required when built). They had a partial alarm system installed about 35 years ago.

The insurance will cover the cost to repair/replace the partial system only, which will require a new FACP, wiring and initiating devices. Insurance will pay for a new system to cover the entire building, if required by code.

We cannot find anything in NFPA 72 that requires the entire building to have alarm coverage. There is no requirement in the IBC for F occupancies (single story, grade level) to have an alarm system.

We do see where non-required systems shall be allowed to be partial.

The question is, since this alarm system is being modified, is there any requirement for the entire building to be alarmed in NFPA 72?

The AHJ would also like to see the entire building to be alarmed, but doesn’t think he can require it by code since it would technically be a non-required system per the IBC.

The only thing he could think of was the requirement for manual pull stations at each exit since the building is not sprinkled. Any thoughts?

Thanks in advance.

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We have an ESFR project with Obstructed Construction and want to be sure we're locating the height of the sprinkler 100% correct. This is an FM-Global project.

We are using K14 ESFR uprights. The bays are 25-ft x 25-ft boxed with W27 beams and contain small bays with W18 beams that are 6'-3" in-between.

As far as I can tell, the sprinkler height is compliant as long as the center of the operating element does not exceed 6-inches below the W18 beams, to a maximum of 22-inches below the deck. So 4-inches maximum below the W18 beams is the target.

We're using Table 8 in FM Data Sheet 8-9 for the design criteria.

Is this approach correct?

Thanks in advance.

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NFPA 13, 2022 Edition, Sections 28.2.4.2.4 says to that a design area can be only the sprinklers within the available design area whenever the available floor area is less than the density/area size.

The next section, Section 28.2.4.2.5, says that when the total flow is less than the density x minimum design area, an additional flow (phantom flow) shall be added at the common point of connection.

When do you apply one versus the other?

If I am interpreting this correctly, you only apply the 28.2.4.2.5 when you have the available floor area, but not the minimum flow?

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Does the requirement under NFPA 25, Chapter 14 for a 5-year internal pipe inspection apply if the system is an open sprinkler/nozzle deluge system?

The system is flowed annually and I believe that this full flow should meet the requirement in lieu of a 5-year internal pipe inspection. 

Am I correct?

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We have a passenger elevator that is a traction, machine room-less (MRL). 

Under NFPA 13, 2013 Edition, Section 8.15.5.2, a 'sprinkler shall not be required for enclosed, non-combustible elevator shafts that do not contain combustible hydraulic fluids.'

NFPA 72, 2013 Edition, Section 21.3.6 states that 'smoke detectors shall not be installed in unsprinklered hoistways unless they are installed to activate the elevator hoistway smoke relief equipment.'

I believe these would apply to this elevator.

Does the elevator only require lobby smoke detectors, including first floor for recall and second floor for alternate recall?

Is a smoke detector actually required within the shaft?

This is my first MRL elevator and I want to make sure we cover everything that's required.

I would appreciate you views on this, thank you!

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For the acceptance testing of a dry pipe sprinkler system, is a 24-hour 40 psi pneumatic test required, or will the 200 psi hydrostatic test alone suffice?

Thanks in advance.

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An overhead door manufacturer was cited a violation from the local AHJ stating that the Storage exceeded 12-ft.

The building in question has two warehouses protected by the same wet system. One side of the warehouse has an approximately 30-ft high ceiling, and the other side is approximately 20-ft high.

The lower side stores doors up to 12-ft in height, on pallets or dunnage in cardboard with strapped packaging. Most of this is straight off the flow without any racking. On small racking unit along the wall with a mixture of cardboard boxes.

The higher ceiling has a few cantilever style racks with overhead doors wrapped in either plastic or cardboard while being strapped. It also has a single-row rack with boxes on conventional pallets. The bottom row has plastic pallets.

​The existing system is currently designed for Ordinary Hazard Group 2.

What classification should this storage fall under? Is OH2 appropriate given the heights and contents? 

Are there further evaluations that would need to be had to arrive at the hazard classification for this?

Thanks in advance.

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Lots of great topics submitted this past month, and lots of great discussion points. We appreciate you all!

We're working on a building that is an old 2-story storage steel building that was fitted with an ill-installed K14 ESFR system. It neglected roof construction, obstructions, and distance from the roof some 20-years ago.

A new owner has removed floor separations, understands that the sprinkler installation must be renewed, but has based the renewal on the possibility of continuing the use of ESFR here.

Due to the roof construction in two large (open but not connected) building sections with about 500 sprinklers each, there are some problems for 5-10% of the sprinklers in these areas. Half of them will have problems with obstructions or distance from the roof and will be "doubled-up" less than 2-ft from a dividing baffle.

For the other half there may be a solution based on lowering these (shown below); light gray are trusses with a slight riser at the upper belt. Green is a part of the horizontal wind bracing crossing H-beams. Red are sprinkler pipes.

The lowered ESFR K25 will have the mid-point of the glass bulb within the maximum allowed distance from the roof (that have a maximum height of 34-ft from the floor). 

Is this an acceptable solution for a small number of sprinklers (one here, one there) in a larger section?

Is there an issue with some of the sprinklers being at the lower limit, while others are higher in elevation?

We can't get rid of the wind bracing, so will the water demand still be based on 12 activated sprinklers even if they're closer together?

​Thanks in advance.

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