Smoke alarms are a requirement under New Zealand Building Code Acceptable Solutions C/AS1 and C/AS2 (for fire prevention) and F7/AS1 (for warning systems). The Acceptable Solutions for clause C require interconnected smoke alarms in all new household units and homes where there are renovations that require a building consent. The Acceptable Solutions cite NZS 4514:2021 Interconnected smoke alarms for houses.
The key requirements around alarm location in the standard are that:
- there must be fire alarms on or near the ceiling in all bedrooms, living spaces, hallways and landings and on each level of a multilevel home
- where doors separate a kitchen from living spaces and hallways, an alarm suitable for kitchens must be installed in the kitchen
- alarms must be within 10 m of each other in any direction.
There is another requirement in the standard (2.2.2(a)) that is causing some confusion – ‘the distance from any wall to a smoke alarm shall not exceed 5 m.’
What exactly does this mean? There are two ways of interpreting these words.
- All walls must have at least part of the wall within 5 m of a smoke alarm.
- All parts of all walls must be within 5 m of a smoke alarm.
The architect who brought this to our attention points out the practical difference between these two points of view: ‘Interpretation 1 implies that a 10 m x 10 m room needs one detector. Interpretation 2 implies that a 10 m x 10 m room requires four detectors, which does not seem sensible.’
In BRANZ’s view, the first interpretation is the correct one. We do not believe that the words ‘the distance from a wall to any smoke alarm’ should be taken to mean that ‘all parts of all walls’ must be within 5 m of a smoke alarm.
This does not imply that a 10 m x 10 m area should be protected by only one alarm. In some cases, supplementary smoke alarms may be necessary to eliminate coverage blind spots, such as those occurring in room corners.