When applying NFPA 13R to a mixed-occupancy (R-2 and S-2) building, what is the definition of "incidental"?

The building in question is three stories of residential over a parking garage designated for residents only. Each residential floor is approximately 2,000 sqft and the garage is approximately 3,000 sqft. The building is type V-A (wood, combustible) throughout.

IBC 2015 Section 509 defines incidental as constituting less than 10% of a given floor.

Does this entire building require a full NFPA 13 system?

If possible, please provide a code basis, thank you!

​​​​​​​​​​​Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe

In an NFPA 13R system does the FDC check valve need to be accessible?

In 13 it states it is required, but I can't find it in NFPA 13R. Section 6.11.4 talks about ball drip for check valve, but I do not see anything on accessible. I’m sure I’m missing some code path that references 13 possibly? Thanks.

​​​​​​​​​​​​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

I have a residential sprinkler calculation out of NFPA 13R 2016.

Do you need to calculate a minimum of 4 residential sprinklers within the dwelling unit?

I have a two-bedroom apartment unit and my most demanding area would be the two that are in the bedrooms and the two that are in the kitchen/living area.

Can I consider the kitchen/living area a compartment separate from the bedrooms and calculate only these two sprinklers?

​​​​​​​​​​​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

We are working on an 8-unit, 4-story apartment building in the City of Chicago. It's an NFPA 13R system, with two units on each floor level. The entire building (all floor levels combined) is about 14,000 sqft.

Are floor-level control valves required?

Under NFPA 13R there doesn't appear to be a requirement for floor-level control valves like there is in an NFPA 13 system (NFPA 13-2016 8.2.4.3). Even still, in NFPA 13 still allows a single control valve and flow switch when the entire building is less than the system limits of 8.2.1 (52,000 sqft for a Light Hazard system). 

Chicago has a Chicago Fire Prevention Code that requires "each floor and level of a building" with a separate control valve (15-16-400), but this and several other sections within the Fire Prevention Code apply only to NFPA 13 systems, not 13R systems.

Might be a shot in the dark but was curious if anyone has ran into this before. Thanks in advance.

​​​​​​​​​​​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

I would like to double check on the coverage of attached garages in an NFPA 13R system.

NFPA 13R 2010 6.6.6: Sprinklers shall not be required in... other concealed spaces that are not used or intended for living purposes or storage and do not contain fuel fired equipment. 

NFPA 13R 2010 6.6.5: Sprinklers shall not be required in any ... carports, and stairs that are open and attached.

There is a separate reference other than 6.6.6 on the coverage of attached garages. The way I read it, they must be covered under this standard. Please advise.

​​​​​​​​​​​​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

In your opinion, what's the best way to address sprinkler design when there are open breezeways separating units in the same building?

Do you somehow provide a heated chase under a deck? Convert from CPVC to steel and heat-trace a run? Go back underground and potentially "under" the building? Use separate risers for each grouping, bumping up the price significantly?

Residential multi-unit apartment complexes are frequently built with open breezeways in-between blocks of units. These usually have paved concrete at the bottom, only wood joists and decking for stairways and walking areas, and a covered roof at the top. 

​​​​​​​​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe​

Sorry if this is too location-specific, but I have a question I'd like to get other designer/engineer input on. The Chicago Building Code (Section 15-16-600) specifically has their own density/area requirements, with a minimum of 0.10 gpm over 1,500 sqft for NFPA 13 applications.

Does this mean that they do not accept residential sprinklers (most demanding 4 adjacent residential sprinklers)? Do they also not accept the area reductions for quick-response sprinklers?

Based on the requirement in the code they certainly have the ability/right to override NFPA 13, I just haven't seen any other jurisdiction overrule the allowances in NFPA 13 and was curious if this holds up for other installers in the area.

​​​​​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Have a 4-story townhouse, sprinklered in accordance with 13R.

Is a sprinkler at the top of an elevator shaft an acceptable trade off for a 1-hour rating of the shaft (in lieu of a 2-hour rating)?

NFPA 13R, 2013 Section 6.6.6 says sprinklers are not required in non-combustible elevator shafts in accordance with ANSI 17.1. The state is says they will not certify the elevator/does not require a certificate in a residential elevator, so there is no confirmation that the elevator code is upheld.

If the sprinkler is an acceptable trade off (or if the sprinkler is elected to be installed in excess of the code requirements) is then a shunt trip and flow switch/heat detector required to shut off power in the event of a sprinkler activation?

​​​​​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Where exactly does a hydraulic calculation need to end? 

When we run a hydrant flow test, there's a static/residual hydrant and a flow hydrant. I regularly run my hydraulic calculations from the building, through the service main, to a street main, and then up the tee'd branch that serves a hydrant so that my source point is exactly at the elevation of the static/residual hydrant. I do this so that I make sure to account for the proper elevation of the water supply.

Most other hydraulic calculations I see will end wherever the building's service main intersects with the street's supply. Is this correct? Wouldn't that place the source at an elevation lower than what the hydrant indicated is available?

Wondering what the proper way is that I should be precisely calculating systems. Thanks in advance.

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Will you please clarify why a Building Area Increase is NOT permitted for an NFPA 13R design?

We are working on a project and the architect has stated that the calculations following IBC T506.2 allow for an area increase up to 135,000 sf. We are working in IBC 2015. The Owner would like confirmation that the 4 story R-2 Type V-A building can be protected under NFPA 13R when it is over 12,000 sf.

​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Why does a townhouse which is 4-story require an NFPA 13R system?

The IRC is specifically geared toward one-and two-family dwellings up to 3 stories, but the IBC allows 13D systems in R-3, R-4 condition 1 and townhouses (903.3.1.3).

Is there another prevailing code reference that overrules this allowance?

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

We are converting a 3 story condo building (was designed to NFPA 13R) to a hotel. The ground floor will have a restaurant, a bar, and a spa. The upper floors will remain residential.

Will the addition of these new occupancies change the whole design of the building? Will the upper level residential units be required to be designed to NFPA 13 standards?

This building is in Bermuda if that helps. Thank you in advance for your help!

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Can an NFPA 13R multi-residential apartment building use commercial concealed pendent sprinklers with standard response instead of quick response?

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Does the proximity of a residence and the number of windows on that residence make a difference in which system type is used (between NFPA 13, 13R, or 13D)? What are the restrictions that would impact the system type?

​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

I have been asked to design a sprinkler system for a 4 story building as per NFPA 13R.  The building has existing standpipes consisting of three 2 1/2” risers.  I am hoping to use the existing standpipe risers to also feed the sprinkler system.  

In this scenario would it make sense to include a hose allowance even though NFPA 13R does not require it?   Also, since NFPA 13R doesn’t require zoning by floor, would it be plausible to have one single “Standpipe & Sprinkler Water Flow Alarm” at the water entry?  

I appreciate and respect your input.  

​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

I have an inspector who wants me to prove that calculating run or through tees is appropriate for 13 Residential systems.

I showed them that run tees are in 13D, he thinks they should be calc'd in 13? How do I prove something is not in a code?

Any help would be appreciated.

​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Does the proximity to a residence and the number of windows make a difference in which system is used (NFPA 13 vs 13R vs 13D)?

​What are those requirements that make it change?

Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

I recently came across your 13, 13R Summary of differences sheet and was wondering if you could explain or site a section that explains how NFPA 13R cannot be considered “fully-sprinklered” for code purposes? Thank you in advance for any help.

Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe