When Can I Use NFPA 13R? (Part I)

For the contractor clients I work with I regularly look over jobs pre-bid. I’ll review drawings, read specifications, and compile all my notes looking for red flags that could impact the job from a design standpoint. (The cheatsheets that I use to breakdown a job is now all in the Toolkit)

Last month I reviewed an apartment complex job for a bid where the code summary had conflicts. The IBC Chapter 5 summary indicated and NFPA 13 system while the IBC Chapter 9 indicated an NFPA 13R system. There were no other references to a fire sprinkler system in the rest of the documents or specifications.

These are the projects that I blame my hair loss on. It's another bad example of project documentation. Regardless, the question of NFPA 13 versus NFPA 13R is something that comes up regularly and is the topic of this and next week's article.

Why Does it Matter?

NFPA 13R is not built with the same intent as an NFPA 13 system.

NFPA 13R systems are designed to “prevent flashover (total involvement) in the room of fire origin”. By doing so, they intend to improve the ability for occupants to survive a fire by evacuation. 13R design is primarily concerned with protecting areas of residential buildings where fires cause loss of life. It is not as concerned with fires in areas where fatal fires in residential occupancies do not originate. (Reference IBC 903.3.1.2 Annex)

NFPA 13 systems, however, intend to provide a “reasonable degree of protection for life and property”. In a general sense, NFPA 13 systems are concerned with both life safety and property protection. The goal is to suppress a fire near its' point of origin, regardless of the level of risk to life safety.

Cost can be largely impacted by the NFPA 13 vs. NFPA 13R decision -
​especially in wood construction buildings with attic spaces and overhangs.

Cost Impact

Aside from having different purposes, NFPA 13 vs. 13R decisions can have major implications on system cost.

NPFA 13R systems allow sprinkler omission in a handful of areas which 13 does not. These include small closets, exterior balcony closets, concealed spaces, elevator machine rooms, garages, carports, attached porches, and attic spaces. I've summarized these with a cheatsheet here.

For wood-construction (a mainstay in residential design), attic sprinkler systems under NFPA 13 can command a major cost premium. These attic systems need dry valves, air compressors, use of steel in lieu of CPVC, special application sprinklers, and design requirements that can require large diameter pipe.

Testing and maintenance is also a long-term ownership concern. Not only do dry attic systems require regular low-point drainage, but they often corrode faster than wet systems . 

Attic systems are one area of a building that can be a huge difference between NFPA 13 and 13R.

That said, I’ve also worked on projects where 13R has little to no impact on the project price. A flat-roof building built with non-combustible structure, for instance, offers no major difference. The only impact was the lower density permitted for residential-style sprinklers. Using the 0.05 gpm/sqft in lieu of 0.10 gpm/sqft of NFPA 13 resulted in smaller pipe diameters for an NFPA 13R system.
​

Buildings must be residential, four stories or less, 60 feet in height or less,
​and not use any code exemptions for an NFPA 13 system in order to use NFPA 13R.

​
When Can I Use NFPA 13R?

There are four global limitations where an NFPA 13R system can be used. These include:

1. The building must be a residential occupancy.
   NFPA 13R Section 1.1 expresses this limitation, as does the IBC 903.3.1.2.
   If the building is mixed-occupancy, the IBC does provide guidance. If any of the non-residential occupancies require an NFPA 13 system, then 13R is not allowed. If non-residential occupancies do not require an NFPA 13 system, then 13R could be used in the residential portions of the building. Non-residential areas would still require protection per NFPA 13. [IBC 903.3.1.2 Annex and Commentary Material]
   
   
2. The number of stories above grade plane must be four or less.
   One exception to this is for pedestal-type construction, where the limitation is four stories above a horizontal assembly instead of grade plane. IBC 510.2 and 510.4 have more information on this.
   
   
3. The height of the building cannot exceed 60 feet (18 meters).
   
   
4. If any code exceptions for an NFPA 13 fully-sprinklered building are used in the building design, then an NFPA 13R system cannot be used.
   
   

Can’t this be determined by the Contractor?

"My project is design/build with deferred submittals. Can’t the contractor determine this?"

No - and I can’t stress this enough – please do not leave this determination to a contractor.

It doesn’t matter if you’re an architect, mechanical engineer, or the expert code consultant. There are a number of code exceptions that can only practically be determined by the design team. The sprinkler contractor is an expert on suppression – not on architectural design decisions and the code paths for those decisions.

What are the building code exemptions that require an NFPA 13 system?

The code exceptions show up for building height increases, building area increases, egress widths, travel distance limitations, occupancy separations, corridor wall ratings, hazardous material increases, inclusion of atriums, unlimited area buildings, allowable area of openings, vertical separation of openings, draftstopping, interior finishes, floor finishes, manual fire alarm systems, and several others.

Sounds like a lot? It is. Fortunately I’ve got a cheatsheet coming next week where I’ll explore these differences in more detail. If you’re interested in getting a copy, subscribe here and it’ll be emailed directly to you.

Other Thoughts

A couple weeks I posted a link on this month’s sponsor Engineered Corrosion Solution’s whitepapers. Many of you have already checked it out, but if you haven't there's a MeyerFire welcome page here: https://www.ecscorrosion.com/meyerfire-welcome

I had a couple people ask about the whitepapers, so here’s a direct link to them. Specifically, be sure to check out "Industry Myths Regarding Corrosion in Fire Sprinkler Systems"  and "Six Reasons Why Galvanized Steel Piping Should NOT be used in Dry and Preaction Fire Sprinkler Systems."

PE Prep Guide 2019 Selling Out

There's been a ton of interest this year in the PE Prep Guide. I genuinely appreciate every single person who's checked out the book for this year's exam  - there has been more interest than ever before and I suspect the exam turnout could be the most ever for the Fire Protection P.E. Exam.

Next year's exam in 2020 will go computer-based and have major changes, so the PE Prep Guide will undergo big changes as well. This year's shipment of the 2019 Edition is just about out, and because of the big changes next year I won't be ordering extra copies. We currently have 16 copies available, so the 2019 edition will likely sell out by October's PE Exam. If you'd like to get a copy of the 2019 PE Prep Guide, please consider doing so now.

After the 2019 Edition sells out we'll still have 2018 PE Prep Guides available, and I'll ship an errata list with it. Any questions, please reach out to me at [email protected].