A large residential unit has a large outdoor terrace/deck.
Would a speaker/horn be required outside in the terrace to alert the occupants in case of alarm?
Normally it isn’t required to have any NAs on the outside unless if the deck is mostly covered and is on a higher floor than the ground. The alarms that are inside normally can also be heard from the outside so most likely not required.
Terrace to me implies this is maybe on a roof? Generally then yes NAs are required on the exterior. They will certainly be required if the only access to the terrace is within the building. Exterior stairways to the terrace may vary from one jurisdiction to another, but generally if it’s attached to the building, I’d plan to have an exterior horn strobe there.
Yes. I see it in new installs all the time. Rooftop Terraces or Patios with speaker strobes. They even will do it on the penthouse level. Usually there is a chiller room and then a large chiller outside, they will put a speaker strobe on the outside too. Or one right outside the roof access door.