Placing smoke alarms correctly

A seemingly simple step in the building process, installing smoke alarms is one that can often be overlooked in the final rush to get everything done – this article will help ensure you get it right

Between 2013 and 2016, approximately one in ten final building inspections carried out by the Auckland Council failed because of smoke alarms that were either installed incorrectly or not at all.

It’s not enough to just install smoke alarms in houses; to work reliably, they need to be the right type, installed in the right place and tested regularly.

Under New Zealand Building Code clause F7 Warning systems, a fire detection and warning system must be provided in all new homes and in existing homes when alteration work is carried out.

Some must-haves with domestic alarms

Acceptable Solution F7/AS1 stipulates that Type 1 smoke alarms are required for risk groups SH and SM, where no other type of fire alarm system is required. Risk group SH applies to houses, townhouses and small multi-unit dwellings. Risk group SM applies to permanent accommodation.

Type 1 smoke alarms are defined as domestic type alarms with an integral alerting device. They must have:

• A hush button, so the alarm can be silenced for at least 60 seconds without cutting the power supply – for example, removing the battery.
• A test button that is easily able to be reached by the building occupants.
• A sound pressure level not less than 75dBA when measured at the sleeping position and not more than 100dBA when measured at 1.8m height (in accordance with NZS 4514:2009 Interconnected smoke alarms for houses).

A range of domestic Type 1 smoke alarms are available that are either battery-powered or mains-connected systems. While mains-connected systems should be interconnected, this is not a requirement in a domestic situation.

Smoke alarms required in rental properties

Smoke alarms are now required to be installed in all residential rental properties. The landlord will be responsible for installation of operational smoke alarms in their properties, and tenants will be responsible for changing batteries and reporting faulty alarm systems.

Location important

F7/AS1 requires smoke alarms to be installed:

• On every level in multi-storey buildings (see Figure 1)
• Either in every sleeping space, or within 3m of a sleeping space door (the New Zealand Fire Service recommends smoke alarms in every sleeping and living space).

Where a single smoke alarm is installed, it should be between the living and sleeping spaces (see Figure 2) in a location that the alarm is given before escape routes become blocked by smoke.

At least two smoke alarms should be installed where sleeping areas are separated by living spaces. For optimum smoke detection, smoke alarms should be located on the ceiling or high on a wall in accordance with NZS 4514:2009.

Dead air spaces, such as corners and spaces near to exposed beams or other ceiling obstructions, must be avoided.

NZS 4514:2009 Figure 5.1 describes areas where dead air spaces may occur (see Figure 3). Install smoke alarms in accordance with the manufacturer’s instructions.

A few places to avoid

 Smoke alarms should NOT be installed:

• In a kitchen, garage or bathroom (unless specifically intended for the space).
• Near a heat source such as a stove, space heater or flue.
• In damp or humid areas such as near showers or in saunas.
• In draughty areas such as near an extract fan or air supply vent.

Different types of smoke alarms

There are two main types of domestic smoke alarm that detect smoke:

• An ionisation alarm monitors ions or electrically charged particles in the air.
• A photoelectric alarm uses a beam of light and a light sensor.

NZS 4514:2009 Table C1 sets out recommendations for alarm types in different locations (see Table 1). Smoke alarms with extra features such as an extra loud alarm sound, flashing strobe lights or vibrating devices are also available for people with hearing impairments.

Recommended alarm types for different locations (based on NZS 4514:2009 Table C1)
Location	Type of smoke alarm
	Ionisation	Photoelectric	Combined ionisation/ photoelectric
Sleeping areas	OK*	OK	Best
Areas seperating bedrooms and rest of house, eg, hallways	OK	Better	Best
Landings in multi-storey units	OK	Better	Best
Living spaces	Better	Better	Best
Living spaces near kitchen	No	OK**	No
Kitchen	No	OK**	No
Bathroom, laundries	No	No	No
Attached garage	No	No	No
*OK is the minimum level of suitability. Better and Best are improvements
**In this situation, smoke alarms have a higher risk of being set off inadvertently, for examply by buring toast, so they should be located as far from the cooking area as possible

Regular maintenance and testing needed

F7/AS1 requires that smoke alarms must be tested according to the maintenance requirements described in NZS 4514:2009. These include:

• Monthly testing by activating the test function to check power supply and alarm sounding device
• 6-monthly inspection and in situ cleaning with a vacuum cleaner and brush to remove dust and dirt that may block smoke entry into the unit – do not use liquid cleaners or solvents as this may damage the unit.
• Annual testing of the smoke-detecting element using a joss stick or commercial smoke alarm test smoke – do not test using a naked flame.

Battery-operated smoke alarms should have batteries replaced annually. The New Zealand Fire Service recommends picking a date that is easy to remember such as the beginning or end of daylight saving.

Replace every ten years

Smoke alarms may have a service life of about ten years. After this, they are likely to become less reliable and should therefore be replaced.

© BRANZ Build Issue 154, June 2016 www.buildmagazine.co.nz