Do I need a smoke detector or a heat detector in an unconditioned garage?

NFPA 72 disallows smoke detectors in spaces that routinely see temperatures below 32°F or above 100°F — that rules out a typical attached garage. A fixed-temperature or rate-of-rise heat detector is the right call there; it will not nuisance-alarm on car exhaust or dust but still trips on a real fire.

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