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g/fire_alarm • Posted by u/fire_code_fred •

AHJ wants survivability on a system that does not require it — reading NFPA 72 Chapter 12 correctly NFPA 72

Four story office building, non-high-rise, standard notification. AHJ is requiring Level 2 or 3 circuit survivability on the NAC risers — two hour rated pathways or a rated shaft.

My reading of Chapter 12: pathway survivability is required where the system serves a partial evacuation or relocation scheme, or in high-rise buildings per 24.3.2. This building is a total evacuation, single stage, non-high-rise. Chapter 12 survivability levels do not apply.

The cost difference is significant — it is the difference between standard FPLR in the riser and either MI cable or a two hour rated enclosure through four floors.

Before I push back, I want to make sure I am not missing something in the 2022 edition. Has anything changed in how Chapter 12 links to occupancy chapters?

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u/admin_jake ADMIN •

Your reading is right. Survivability is driven by the notification scheme, not by building height on its own, and a total evacuation system in a non-high-rise does not trigger it.

The productive path is the same one that works on any AHJ disagreement — ask for the specific code section in writing. Not confrontationally. "So I can document this correctly for the submittal, which section are you citing?" Most of the time you either get a section you can discuss or you get a reconsideration.

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u/suppression_sue •

One thing to check before you push: is there anything in the local amendments? A surprising number of jurisdictions amend survivability requirements downward in height, and if this county adopted a local amendment at four stories, the inspector is right and NFPA 72 alone will not tell you.

Look at the adopting ordinance, not just the model code. I have been embarrassed by exactly this.

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u/fire_code_fred OP •

Checking the ordinance today. That is the failure mode I am most likely to have — I know the model code well and I do not always read the local adoption.

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u/estimator_erin •

From the estimating side: if you are going to contest it, price both and put the survivability version in as an alternate with the cost broken out. Owners engage very differently with "the inspector is requiring something that costs $84,000" than with "we are in a code dispute."

Make the number visible and the owner will often make the phone call you cannot make.

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u/fire_code_fred OP •

That is a good instinct. The owner has a relationship with this jurisdiction that I do not, and a phone call from them lands differently than a letter from the fire alarm contractor.

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u/panel_programming_paul •

Also worth asking whether the owner has any plans for the building that would change the scheme. If there is any chance this becomes a relocation or partial evac system later — a tenant fit-out with a defend-in-place area, say — then the survivability is going to be required eventually and doing it now is cheaper than doing it in the riser of an occupied building.

Sometimes the AHJ is wrong about the code and right about the building.

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