Carbon Monoxide Alarm Requirement and Count (IRC R315)
The companion to the smoke-alarm tile, and the contrast is the point. CO alarms are required only where there is a SOURCE -- R315.2 triggers on a fuel-fired appliance installed in the dwelling OR an attached garage -- so an all-electric house with a detached garage legitimately has none, and the attached-garage trigger is the one people miss. And even when required, the alarm goes OUTSIDE each separate sleeping area, NOT in each bedroom; applying the smoke-alarm count to CO is how people buy several too many. The single case that puts one inside a bedroom is R315.3\u0027s exception, a fuel-burning appliance in that bedroom or its attached bathroom. A per-story rule is NOT in the model IRC -- many states amend one in, so it is an explicit toggle rather than a hidden default.
Formula and source
required when a fuel-fired appliance is installed in the dwelling OR the dwelling has an attached garage; alarms = one outside each separate sleeping area, plus one inside each bedroom containing a fuel-burning appliance in the bedroom or its attached bathroom, plus (only where a local amendment adds it) one per story beyond the first.
IRC R315.2 (where required, for new construction: outside each separate sleeping area in the immediate vicinity of the bedrooms, in dwelling units within which fuel-fired appliances are installed and in dwelling units that have attached garages) and IRC R315.3 (location, with the exception placing an alarm within a bedroom where a fuel-burning appliance is located in that bedroom or its attached bathroom).
Audience
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