Why does nobody talk about the fire code rule on smoke detector spacing in old buildings?

I was reading through the 2021 NFPA 72 handbook last week for a job in a 1920s brick apartment house. I always thought the 30 foot rule for smoke alarms was pretty solid. But the book said in rooms with ceilings over 10 feet high, you need to cut that spacing down to 21 feet. I've been putting them 30 feet apart in these high ceiling lobbies for years. It makes sense when you think about how smoke spreads, but I never had an inspector call me on it before. Found it on page 29.4.3.1. Now I'm going back to check my last three jobs in similar buildings. Has anyone else run into this, or had an inspector actually measure the spacing on a final?

3 comments

3 Comments

knight.uma10d ago

Yeah, that's the kind of thing you find at 2 AM when you're double checking something else and your stomach just drops. Makes you feel real smart for a minute. I bet half the inspectors don't even carry a tape measure that long, they just look to see if you have them in the general area. Still, good catch. Now I'm paranoid about the last warehouse I did.

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beng5110d ago

Know a few inspectors who take that stuff deadly serious, man. They absolutely have the long tapes and they love to use them. Saw one make a crew re-stack a whole pallet rack over two inches once. It's not about being mean, it's their job on the line too if they sign off and something fails. That paranoia you're feeling? That's the system working, honestly. Better to find it yourself at 2 AM than have them find it at 10.

claire_ross6110d ago

Read an article last year where a safety guy said the best inspectors ARE the paranoid ones, @knight.uma. They have to picture everything that could go wrong. That two inches beng51 mentioned isn't about being picky, it's about the whole load shifting later. My cousin works logistics and said their new place laser scans everything now because tapes can lie. Makes sense, you want it right. That 2 AM find is your own brain doing the inspection first, which is kinda cool.