Fire safety

Few older houses will meet modern fire safety standards. Renovation provides an opportunity to bring improved fire safety.

Until fairly recently, fire safety was not generally a significant consideration in house design and construction, and some older timber houses are likely to burn readily.

Generally, hard lining with plasterboard reduces the risk of fire spreading within a house but there is still a significant fire load from furnishings.

In any fire, smoke and toxic fumes – not the flames from house fires – generally cause fatalities. Fires from upholstery foam, bedding materials and plastics will smoulder and produce toxic gases but few flames, while fires from burning wood or cooking oil will produce hot, fierce flames. 

Designing for fire safety

The design process of renovations must include fire safety consideration. This may include:

  • installation of smoke alarms (mandatory)
  • installing a fire extinguisher in the kitchen
  • installing heat detectors 
  • consideration of a domestic fire sprinkler system.

Chimneys will also need to be assessed for fire safety if the fireplaces they serve are to be used for heating.

Flat conversions

Fire safety may also be an issue where the villa has been or is being converted into two dwelling units. For original conversions, the work that was done may not have met the fire separation requirements at the time of the conversion, and for new work, the requirements of Building Code clause C Protection from Fire will need to be met.

Heaters and other appliances

All appliances that burn gas, oil, solid fuel or any other combustible material must be installed to ensure that:

  • the combustion process does not raise the temperature of any adjacent building element to a level where its performance is affected 
  • the accumulation of combustion gases within the building is avoided.

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Smoke alarms

With most renovations, installing smoke alarms is a legal requirement.

Smoke alarms detect the smoke particles from a fire. There are two common types:

  • A photo-electric smoke alarm, which uses a beam of light and a light sensor. When smoke particles affect the amount of light reaching the sensor, an alarm will sound.
  • An ionisation smoke alarm, which monitors the ions (electrically charged particles). When the electrical balance of the air is altered by the smoke particles, the alarm will sound. 

The NZ Fire Service recommends that photo-electric alarms be installed in households or, if ionisation alarms are currently installed, they should be supplemented with photo-electric alarms as these provide more effective all-round detection.

Smoke alarms are available with extra loud alarms, flashing lights or vibrating devices for people with hearing loss.

To be effective, an installed smoke alarm must be operating properly, audible through closed doors and able to detect smoke from all types of fires.

Domestic smoke alarms are typically battery-powered and provide good warning of the presence of smoke and fire as long as batteries are replaced regularly. Mains-connected systems (with battery back-up in the event of a power failure) are also available.

Domestic smoke alarm requirements 

The New Zealand Building Code requires that all existing houses undergoing alteration (as well as new houses) have smoke alarms installed. Domestic smoke alarms must be Type 1, which has:

  • a hush button so the alarm can be cleared without shutting off power (i.e. by removing the battery) 
  • a test button.


Smoke alarms should be installed: 

  • on (preferably) or near the ceiling
  • on the escape route of each floor level of a household unit
  • in every sleeping space or within 3.0 m of a sleeping space door
  • in sleep-outs.

Note: The NZ Fire Service recommends installing them in every sleeping and living space. 

If a smoke alarm must be located on a wall, install it 100 mm from the ceiling and 600 mm from a corner to avoid dead air pockets.

Do not install smoke alarms: 

  • in a kitchen, garage or bathroom unless specifically designed for these spaces – heat detectors can be installed in these spaces instead
  • close to a heater flue or an extract fan.

Maintenance of smoke alarms

Maintenance of smoke alarms includes:

  • monthly testing of the alarm test facility
  • annual, in situ cleaning with a vacuum cleaner (no disassembly required)
  • replacement every 10 years.

Domestic sprinklers

Sprinklers provide the most effective protection against fire damage, and systems suitable for domestic installations are available. If a fire starts, the sprinkler heads immediately above the fire will discharge water.

The most common domestic fire sprinkler systems:

  • use a glass bulb, heat-sensitive element 
  • activate at about 68°C 
  • have a flat and wide spray pattern with small and medium droplet sizes 
  • have sprinkler heads that may be concealed, flush-mounted, side-wall or pendant type
  • require a 20 mm diameter pipe connection.

If a fire develops, not all sprinkler heads will operate, but only those closest to the fire – 65% of fires are controlled by a single sprinkler head, and 95% are controlled by five sprinkler heads or less.

When a sprinkler head is set off, the fire brigade is also called.

Installation and maintenance

The design and installation of a domestic sprinkler system must be carried out by a qualified practitioner, with independent inspection and certification.

Maintenance and testing should be in accordance with the relevant standards and in accordance with the manufacturer’s instructions.

(Updated 15 November 2013)