Fire Safety in Three Storey Houses NSW

In a fire, the people on the top floor of a three storey house have the furthest to go to reach safety. The building code relies mainly on early warning to give them that time. Good design choices then make the route out simpler. This guide covers both.

How the code treats a three storey house

A single house is a Class 1a building under the National Construction Code, whether it has one storey or three. In NSW, houses are currently built to NCC 2022 using the ABCB Housing Provisions. For a standard house, those provisions do not call for fire stairs, exit signs or sprinklers. Instead, they focus on:

smoke alarms that wake people early
walls that slow fire spreading between neighbouring buildings
safe stairs, balustrades and windows
extra construction rules on bushfire prone land

Smoke alarms throughout the house

Smoke alarms in a Class 1a house must:

be installed on every storey, including storeys with no bedrooms
be placed in the hallway serving bedrooms, or between the bedrooms and other living areas if there is no hallway
comply with AS 3786, the Australian Standard for smoke alarms
run off mains power where the house has a mains supply
be interconnected whenever the house has two or more, so all of them sound together

Interconnection matters a lot in a three storey house. A fire starting in a ground floor living area needs to set off the alarm outside the top floor bedrooms straight away. Think about placement near the stair too, because smoke rises up the stairwell quickly.

Planning the route out

In most three storey houses the internal stair is the only way down. Some simple design choices help:

keep bedrooms close to the stair, so nobody has to pass the kitchen or living area to reach it
avoid placing the kitchen, a fireplace or a garage door at the bottom of the stair
use front and back door locks that open from inside without a key
consider a balcony or terrace on the upper levels as a place to wait for help

Windows can play a part, but they also have to stop children falling. Under the Housing Provisions, once a bedroom floor sits 2 m or higher off the ground outside, openable bedroom windows need a restrictor or screen, unless the opening starts 1.7 m or higher above the floor inside. Windows in other rooms need protection when the floor sits 4 m or higher above the ground. If a restrictor can be unlocked or removed, the code asks for an extra barrier as well. Fall protection and escape can pull in different directions, so talk the window choices through with your designer early.

Fire spread to and from neighbours

Taller houses on narrow lots often sit near their side boundaries. Any external wall less than 900 mm from a side or back boundary, or less than 1.8 m from another building on the same lot, must be built to resist fire. The usual options are a wall with a fire resistance level of 60/60/60, or masonry at least 90 mm thick. Windows in that part of the wall must be fire protected, with limited exceptions for small windows to bathrooms and laundries. The wall must also run up to the roof, which matters on a three storey elevation.

Bushfire prone land

If your planning certificate shows bushfire prone land, the house must be designed for its bushfire attack level, using AS 3959 and the NSW RFS planning guideline. That affects glazing, decks, roof details and screens on every level.

When a house is not just a house

If the house will be used as a small boarding house (Class 1b), the rules step up. Smoke alarms are needed in every bedroom, and lighting must come on automatically to help people find their way out. See our boarding houses service if this applies.

How it is checked

Fire-rated walls near boundaries are checked at the frame stage, and smoke alarms are tested at the final inspection, ahead of the occupation certificate. A plan assessment can pick up layout issues early. To discuss your design, see our three storey homes service or request a quote.

Local help across NSW

CertifiBuild certifies Class 1 and Class 10 work in 39 council areas. Local rules on these council pages are a good place to start: Blue Mountains City Council, Ku-ring-gai Council, North Sydney Council, Campbelltown City Council, Hunter’s Hill Council, Inner West Council.

Suburb pages with local planning notes: Leichhardt, Springwood, St Ives, St Leonards, The Junction, Waverton, Wedderburn, Wentworth Falls, Winmalee, Woolwich. You can also browse every service area.

Fire safety and getting out safely in a three storey house