Narrow lots often push the garage hard up against a side boundary. When that happens, two separate sets of rules apply. Planning controls decide how close the garage may sit, and the building code decides how its walls must be built so a fire can't easily spread to or from next door.
Setbacks and fire separation are different checks
Setbacks come from planning instruments. Complying development relies on Housing Code setbacks from the Codes SEPP. For a DA, they come from council's local environmental plan and development control plan. A garage has no exempt pathway in NSW, so one of those two approvals is always needed.
Meeting the planning setback does not prove the fire design is right. Fire separation is set by the National Construction Code (NCC). For houses and garages, the standard compliance route is set out in Part 9.2 of the ABCB Housing Provisions. The edition in force in NSW today is NCC 2022.
The 900 mm and 1.8 m triggers
Under the NCC, a house is a Class 1 building and a garage is Class 10a, meaning a non-habitable building. The fire rules switch on at two distances:
- 900 mm from an allotment boundary. This does not include a boundary with a road or public space.
- 1.8 m from another building on the same lot.
Distances are measured at right angles to the boundary or the other building. Only the part of a wall inside that distance needs protection, not the whole wall.
For a garage near a boundary, the Housing Provisions give a few acceptable layouts. The garage can stay at least 900 mm off the boundary. Or any garage or house wall inside 900 mm of the boundary can be built as a fire-resisting wall. Or the house can be kept 900 mm or more from the garage. Similar options apply, using 1.8 m, when the garage sits near another building on the same lot.
What a fire-resisting wall looks like
The Housing Provisions accept any one of these:
- A wall with a fire resistance level (FRL) of at least 60/60/60, tested from the outside. The three numbers are minutes of structural adequacy, integrity and insulation.
- Masonry at least 90 mm thick.
- Masonry veneer where the outer skin is at least 90 mm thick.
The wall must start at the footings or slab and run up to the underside of a non-combustible roof covering or eaves lining. It may stop up to 200 mm short of the roof covering if that gap is closed off with a non-combustible fascia, gutter or flashing.
Openings are where many designs come unstuck. A window or door in the protected part of the wall generally needs to be a fixed fire window, construction rated at least -/60/-, or a self-closing solid core door at least 35 mm thick. Small exceptions exist for some non-habitable room windows, and for vents, weepholes and service penetrations.
Eaves, gutters and other projections
Things attached to the wall also count. The Housing Provisions list which items can project into the 900 mm zone, such as non-combustible fascias, gutters and downpipes, light fittings and meters. Eaves get a tighter limit and need non-combustible cladding and lining. If you are planning a boxed gutter or wide eave on the boundary side, check the detail early.
An open carport is handled differently. If it has enough open sides and a polycarbonate or non-combustible roof, and doesn't support the house, it can be exempt from some of these rules. Our When a carport needs no approval, and when it does explains the planning side.
Problems we often find on site
- A timber framed wall lined with cladding that was never tested as a fire-rated system.
- A window, roller door motor penetration or exhaust fan in the protected wall with no fire treatment.
- The fire-rated lining stopping at ceiling height instead of continuing to the roof.
- Gutters or footings that cross the boundary line.
- A later plan to use the garage as a room, which changes its class. See our article on Garage to habitable room: what changes in a conversion.
Ask your supplier for the test report or system specification for any fire-rated wall product, and keep it for your certifier. The frame inspection, before linings go on, is the right moment to confirm the system is installed as tested. Our Critical stage inspections: what we check and when covers when that happens.
CertifiBuild checks garage fire separation as part of every CDC and construction certificate for garages and carports. You can have the plans assessed before lodging, or book an inspection at least 48 hours ahead.
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: City of Canada Bay, City of Parramatta, Canterbury-Bankstown Council, Inner West Council, Hornsby Shire Council, Kiama Municipal Council.
Suburb pages with local planning notes: Concord, Concord West, Ermington, Greenacre, Haberfield, Hornsby, Kiama Downs, Lake Munmorah, Lalor Park, Lambton. You can also browse every service area.
Sources
- Housing Provisions Part 9.2, fire separation of external walls (ABCB)
- Part H3 fire safety, NCC 2022 Volume Two (ABCB)
- Fact sheet on exempt and complying carports and garages, NSW Department of Planning