Along with a raft of other changes as a result of the leaky building crisis, the building code was changed in 2003 to require smoke alarms to be fitted to all residential buildings.

This doesn't mean that a council inspector will come knocking on your door to check if you have fitted the alarms. But it does mean that a code compliance certificate won't be issued - for any building work that requires a permit - until the alarms are fitted.

The rules

According to rules set down by the Building Code, smoke alarms must be "type 1" units. This means they must have a hush button - to allow nuisance alarms to be cleared without removing the battery - and also a test button.

As well, they must comply with at least one of the following standards:

• UL 217
• CAN/ULC S531
• AS 3786
• BS 5446:Part 1

Where to fit alarms

According to the rules, smoke alarms must be located in escape routes on all levels within the household unit. On levels containing sleeping spaces, they must be installed within the sleeping space, or within 3 metres of every sleeping space door. And they must be audible through closed doors.

Alarms must be installed on or near the ceiling, and in accordance with manufacturer's instructions.

You will need several alarms for large houses or multi-level houses. If you buy the inter-connectable type and wire them up, all will go off together. Tests have shown an upstairs alarm in the stairwell is likely to respond before one fitted downstairs, even when the fire is downstairs.

 The NZ Fire Service also has advice on where to place alarms.

Report by Bill Whitley.