Phone Retail Space as Light or Ordinary Hazard?

8/1/2025

I'm working on a tenant improvement for a retail storage for a very large & common phone company. The architectural plans list the occupancy as Business.

I’ve designed one of these before, and when I pulled up the drawings from that previous job, the architect labeled it as Mercantile, so I designed it at 130 sqft spacing under Ordinary Hazard Group 1.

Now, on this current project, there's no mention of Mercantile—only Business.

The space is straightforward: a sales floor and a restroom in a 1,218-square-foot area.

Can this be designed as Light Hazard?

Looking at NFPA 13 (2019), Section 4.3.3 – Ordinary Hazard (Group 1) (using NFPA Link), the enhanced commentary refers to OH1 as covering “most light manufacturing and service industries where the use of flammable and combustible liquids or gases is either nonexistent or very limited.”

That doesn’t really sound like a retail cellphone store to me. Even in the Annex, A.4.3.3 OH1 (6): Electronic Plant—this doesn’t seem anywhere near that level of hazard.

Could someone help me out here?

I get that I could just design to 130 sqft spacing and be safe, but I’m really aiming to understand and apply the right classification—not just overdesign.

Trying to be the best, most informed designer I can be. Thanks for your time and any insight!

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16 Comments

Chad

8/1/2025 08:02:50 am

Are they usually selling things that you can take away? Is merchandise on display? If yes then its mercantile.

2021 IBC:

309.1Mercantile Group M.
Mercantile Group M occupancy includes, among others, the use of a building or structure or a portion thereof for the display and sale of merchandise, and involves stocks of goods, wares or merchandise incidental to such purposes and where the public has access. Mercantile occupancies shall include, but not be limited to, the following:

Department stores

Drug stores

Markets

Greenhousesfor display and sale of plants that provide public access.

Motor fuel-dispensing facilities

Retail or wholesale stores

Sales rooms

Wes

8/1/2025 08:10:35 am

A caution here - Building Occupancy, as defined in the IBC, is relevant architecturally. It's designated by the architect (or a code consultant) for purposes of classifying risk for a building.

That doesn't necessarily match what we have to accommodate on the fire sprinkler system design. We accommodate the hazard that's posed in the building, in terms of fuel type and fuel load. This is discussed specifically in NFPA 13 (2025 Edition) 4.3.1.2 and the enhanced and annex material.

"NFPA 13 FAQ: Are the occupancy hazards contained in NFPA 13 the same as the hazards presented in other NFPA documents? No, the occupancy hazard classifications are not intended to coincide with or align with the occupancy classifications in other NFPA codes and standards."

The classification here concerning the sprinkler design criteria should come from NFPA 13, not the IBC. A qualitative argument could be made that a jewelery store is a very light combustible load, similar to furnishings in a Light Hazard office or less. A more black-and-white argument could be made that NFPA 13 A.4.3.3.2 lists Ordinary Hazard Group 2 occupancies (sprinkler occupancy hazard classification, not building occupancy) includes having uses and conditions similar to the following: mercantile.

Am interested in others' take here. I would personally design it as OH2 so it can be re-swapped in the future with most other tenants and not create any controvery - but my input here is that the fuel load and occupancy hazard classification stems from NFPA 13 and not the Building Occupancy that's defined in the IBC.

jakob cirell

8/1/2025 08:20:31 am

Occupancy Classification through NFPA 13 seems like the proper route. I would also look into whether you need to go the route of commodity classification, if there is storage of significant amount of electronics with lithium-ion batteries.

8/1/2025 08:27:47 am

Its OH2 all day in my opinion because mercantile is listed as you said in the annex and that is how I enforce it locally.

It not a strict one to one matching of IBC occupancies to hazard classes. Its what they state the use is on the Owner's certificate. They might say we sell electronics or a retail store, but its not a business office. Merchandise is on site for sale, no matter how little it is and barring some odd local arrangement nothing is stopping them from filling the space with boxes for cell phone accessories or anything else they want to sell. They have the ability to load it right up if they are classified as mercantile and zoned for it.

I am not suggesting you need to design for future use, you are designing for what's the permissible and planned use in that space's new proposed use no more/less. I would not draw a parallel to Storage occupancies and say you need ESFR everywhere.... Tell me on the owner's certificate how you plan on using it and ensure the protection is aligned with that.

It only makes sense to do it now unless there is a really crappy water supply... If its a cell phone store today, it will eventually be a retail store (maybe restaurant) tomorrow.

Glenn Berger

8/1/2025 08:35:00 am

You got some pretty good responses from Chad & Wes already. Building / Room names are good to have, but the actually way the space is being utilized must govern.

Dan Wilder

8/1/2025 08:39:47 am

Without knowing the building construction, this is a guess.

Likely, the reason it is classified as a "B" occupancy is the tenant space has an occupant load less than 50 which allows the lower classification. There also may be a square footage limitation allowance. Finally, due to the building being fully sprinklered, that also has some benefits.

There are a lot of allowances and exceptions that should be spelled out on the Code Analysis sheet of the permit set. Check there for the path taken.

Joe

8/1/2025 10:19:16 am

Too often people interpret a fire sprinkler class with what is happening in a space or the likelihood of fire. In actuality sprinkler hazard classification is dependent upon heat release. The appendix of NFPA13 gives unofficial rule of thumb guidance. However since heat release is rather significant calculation, this is the reason that this portion of "design" is often considered "Engineering". This decision can be made with full blown specific calculations or an educated opinion. For this reason I eventually grew fond of collaborating with an engineer to make my design decisions with full confidence. This doesn't answer your question does it?

8/1/2025 10:24:08 am

BTW - The building code is a system, so you also have to confirm what requirements the overall building design requires or has taken advantage of tradeoffs.

8/1/2025 10:39:50 am

that's fair... Would you agree that even a sparsely filled sales floor (like this) will be adequately protected by 0.1GPM/SQ FT but the stock rooms will need 0.2PGM/SQFT because that is really the bulk source of heat release potential.

Therefore that's what you would design to given that no one is going to compartmentalize a stock room in this specific case? And nothing is stopping them from filling up that sales floor for a clearance sale.

Peter Howard

8/1/2025 10:21:47 am

I'd default to ordinary if it's retail space. But Dan Wilder has given the "correct answer" here. The architect's code analysis sheet should be the dominant guideline.

Jesse

8/1/2025 10:30:14 am

The B occupancy is from IBC. In Automatic Sprinkler design, we typically don't design to IBC as that's used primarily to identify WHEN sprinkler protection is required. The HOW to protect it is from NFPA 13.

NFPA 13 identifies Mercantile as OH2. OH1 is one of those occupancy hazard classes with a pretty limited application. As a geneal rule, I always design (and calc) retail / mercantile as OH2 unless its a big box store or has a large stock room that may push it higher

Gary Sims

8/1/2025 10:30:22 am

What Wes and Chad said above. Wes nailed it... but as Chad stated, be an owner advocate and set them up for success in the future. Dan is also correct. I love this platform!

Jon N

8/1/2025 01:49:25 pm

Some great comments have been made here and this is an area that I have some interest in. Building/fire code occupancy classifications, NFPA 13 commodity hazards, and the reality of fuel loads do not always correlate. For instance, review the NIST studies and videos on office cubicle fires. The heat release rates (HRR) on these fires often exceeded 6MW yet NFPA 13 protects office uses with light hazard density. One of the original tests on retail / mercantile fires was from Europe (England?) where a rack of clothing was burned with a HRR of around 5MW (sorry, I don't have the exact report in front of me). That became the basis for mercantile needing to have greater protection criteria. So, my question becomes, if light hazard fire sprinkler density can protect office fires with a higher HRR, why can't they protect a low-risk cell phone store. All too often we get hung up on definitions and the technical requirements of the codes and standards and we ignore "common sense" and fire physics. To quote one of the nation's greatest fire protection engineers (Bud Nelson - RIP): "If the answer defies the laws of fire physics or common sense, the answer is wrong."

8/1/2025 03:12:04 pm

Wait....so all my fire protection paperwork in my office (vertical/horizontal loose and tight rolled paper storage, shelving, the open file cabinet under my desk that magically gets filed over every weekend...) isn't protected FROM fire?!?

Feeling a little slighted...and apparently under protected

Jeff Ayers

8/1/2025 02:34:37 pm

Did the EOR specify the classification? Even in a delegated design, the EOR specifies the classification of light, ordinary hazard etc. on which you base your sprinkler bid.

Also, you said the Arch drawings state the occupancy is Business, but they should have also stated the use group, which is relevant.

You also said "Now, on this current project, there's no mention of Mercantile—only Business." Who "mentioned" that it was Mercantile? The AHJ? The EOR? and what does it matter what is mentioned if it is not in the cow, on this current project, there's no mention of Mercantile—only Business Contract Documents?

Jack G

8/1/2025 06:07:46 pm

It’s all been covered above.
Merchantile — oh-2.
And if it’s a tenant space it’s best to go with OH for flexibility for future tenants.

Phone Retail Space as Light or Ordinary Hazard?

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