It needs to be conditioned space. Is it? Think garage
So you are saying if an new addition or attached garage is not conditioned they don't need to put in any fire alarms in the house complying to code at all if there is not any existing? Is that an exception in newer codes?
2015 IRC
R314.2.2 Alterations, repairs and additions. Where
alterations, repairs or additions requiring a permit occur,
or where one or more sleeping rooms are added or created
in existing dwellings, the individual dwelling unit shall be
equipped with smoke alarms located as required for new
dwellings.
Exceptions:
1. Work involving the exterior surfaces of dwellings,
such as the replacement of roofing or siding,
the addition or replacement of windows or doors,
or the addition of a porch or deck, are exempt
from the requirements of this section.
2. Installation, alteration or repairs of plumbing or
mechanical systems are exempt from the requirements
of this section.