they may already be hard-wired- but they're 10-15 years old and might be failing. I've been holding off since I'll have to update the system if i can ever get the addition started. (this time it's the architect that's MIA after a trip to Scotland at the beginning of the month. I need the elevations to get a 3rd estimate)
(attic access is there- but not easy. A ladder is needed for access, and then there is only a small walkway across the beams, and the connections to the alarms (if they exist) are under blown in insulation)