Garage and carport certification

When does a carport need no approval?

A carport that is exempt can be built with no approval. Where the lot is 300 m² or smaller, an exempt carport can cover up to 20 m². On bigger lots the cap is 25 m² in most zones and 50 m² in large-lot residential or rural zones. Its height is capped at 3 m above ground. Where it joins a house of one storey, it must stay below that house's gutter line.

It must have a minimum of 2 open sides, and at least a third of its perimeter must be unenclosed. It has to be set back no less than 1 m from the building line. In most zones it must keep 900 mm off the side and rear boundaries, or 5 m in most large-lot residential or rural zones. The roof may extend over that gap but must keep 500 mm clear of the boundary. Rainwater from the roof has to drain into your existing stormwater system. Any fixing to the house fascia needs an engineer's design.

Can a garage skip approval?

No. Every garage needs approval. Under the CDC rules (a quicker approval granted by a private certifier), a detached garage can reach 4.5 m in height above ground. Street-facing garage doors can total 3.2 m in width where the lot is 8 to 12 m wide, or 6 m where it is over 12 m wide. Where the lot is under 8 m wide, a garage is only allowed if vehicles reach it from a lane, a secondary road or a parallel road.

Garages close to boundaries or other buildings

The building code has fire rules for a garage or carport that sits between your house and a boundary, or between your house and another building on the lot. They stop fire spreading to the house. The usual fix is to keep it 900 mm from the boundary or 1.8 m from the other building, or to build walls that meet the code's external wall fire rules. Boundaries facing a road or public space are not caught.

An open carport may fall outside these fire rules. A third or more of its perimeter must be open, across two or more sides. The roof must be polycarbonate or non-combustible. Any ceiling lining and wall cladding must be non-combustible. The carport must not support the house in any way. A side closed by a garage door does not count as open, so adding a roller door later can change the fire design.

Driveways and kerb crossings

A new driveway or kerb crossing needs separate approval from the road authority, usually council. New driveways for complying development garages should also follow AS 2890.1, the off-street parking standard. Plan the crossing, driveway slope and garage floor level together, because a steep driveway is hard to fix once the slab is poured.

Can your lot use complying development?

The complying development certificate (CDC) pathway for garages and carports is limited to residential land in the R1 to R4 zones, plus RU5 village land. The lot must measure at least 200 m² and be no narrower than 6 m. Rural zones are dealt with under a separate code, the Rural Housing Code.

The new structure also has to fit within the floor area allowed for the whole lot. If the house already uses most of the permitted gross floor area, a large garage can push the total past the limit, and the proposal must then be lodged as a development application (DA) with council.

Where cars enter from the primary road, the minimum setback is either 5.5 m from that road or a position 1 m further back than the front building line, whichever the house's own front setback calls for. On a battle-axe block, the structure has to be placed so vehicles can drive out of the site forwards.

Carports on heritage, foreshore and bushfire land

An exempt carport is not permitted on a lot that holds a heritage item or draft heritage item, or anywhere in a foreshore area. Inside a heritage conservation area, an exempt carport has to go in the rear yard. Land listed on the State Heritage Register or protected by an interim heritage order also falls outside the exempt rules.

On bushfire prone land, any carport closer than 5 m to the home has to use non-combustible materials throughout. Wherever the lot is, metal roofing and posts need a factory pre-coloured finish with low reflectivity.

Each house can have one exempt carport, or two when a principal dwelling and a secondary dwelling share the lot. The work also must not reduce vehicle access to the site or cut into existing parking. Miss any of these conditions and the exempt route closes, so the carport then needs formal approval.

How a fire-rated garage wall is built

Where a garage wall needs fire protection, the National Construction Code (NCC) Housing Provisions describe how to build it. The wall starts at the footings or ground slab and rises to meet the underside of a roof covering that is non-combustible. It can stop up to 200 mm short if the gap is sealed with a non-combustible fascia, gutter or flashing, or it can finish at a non-combustible eaves lining instead.

The wall's fire resistance level (FRL) must be 60/60/60 when exposed to fire from the outside, or the wall must be solid masonry 90 mm or more thick, or masonry veneer with an outer skin of 90 mm or more. A framed wall needs a tested system that achieves that rating.

Openings in that wall must be protected, for example by fire windows that cannot be opened, or by solid core doors 35 mm or thicker that close themselves. Vents, weepholes, control joints and service penetrations are exempt. Confirm these details before ordering windows or a door for a wall close to the boundary.

Termite protection where garages join the house

The NCC applies termite risk management to Class 1 and Class 10 buildings in areas where subterranean termites are known to be a risk. Any primary building element that termites can attack, such as untreated timber framing, needs a termite management system. Steel, concrete, masonry and suitably resistant or treated timber are treated as not subject to attack.

The system has to meet AS 3660.1, or pass the tests in Section 5 of AS 3660.3. A durable notice goes up somewhere easy to find, with the meter box suggested as a location. It records the system used, the date it was installed and the inspections the installer recommends.

Attachments such as carports, steps, decks and downpipes can give termites a hidden route into the house. The Housing Provisions call for an inspection zone between an attachment and the building, so a carport fixed to the house should be detailed with that gap in mind.