Three Car Garage (Triple Garage) in Australia: Sizes, Costs, Council Approval, and Design Options

What size is a three car garage in Australia?

A true three car garage (triple garage) normally provides three clear vehicle bays plus safe door swing and circulation. In Australia, common triple garage dimensions are:

• Typical footprint: 9.0 m (width) x 6.0–7.5 m (depth)
• Three car garage width: 8.4–9.6 m overall (3 bays at ~2.8–3.2 m each)
• Door clear opening: 2.4–3.0 m per bay; door height 2.1–2.7 m (choose 2.7 m for lifted 4WDs)
• Eave height: 2.7–3.6 m depending on vehicles, racking, or mezzanine storage

Popular triple garage sizes in Australian kit form include 9 x 6 m, 9 x 7 m, and 10.5 x 7 m. If you need workshop space, add 1–2 m of depth or a lean-to to create a 3 bay shed with awning.

What are the best shed materials for Perth’s climate?

For hot, dry summers and coastal exposure, most buyers choose Colorbond steel cladding over Zincalume for a triple garage or three bay shed in WA. Color selection, heat reflectivity, and marine-grade variants matter near the coast.

Colorbond vs Zincalume — Which is better for WA conditions?

Tip: Specify matching gutters/downpipes, cyclonic fixings (where required), and sarking/insulation to reduce heat and condensation.

Related terms to know: Colorbond vs Zincalume comparison, steel sheds Perth, custom Colorbond garages Perth, rural sheds NSW, custom carports Melbourne.

How much does a 3 bay shed or triple garage cost in 2025?

Indicative 2025 pricing in Australia (ex GST, supply-only unless noted):

• DIY 3 car garage kit (non-cyclonic, 9 x 6–7 m, Colorbond): $12,000–$25,000
• Installed triple garage (concrete slab, erection, doors, basic electrical): $28,000–$60,000+
• Cyclone-rated sheds QLD/WA Region C–D: +15–35% for heavier frames, wind-lock roller doors, extra fixings
• Concrete slab 100–125 mm with SL72/SL82 mesh and edge beams: $120–$220/m² region-dependent
• Lean-to/3 bay carport awning (3–4.5 m deep): $3,500–$12,000 depending on span and posts

Costs vary by wind rating, bay width, eave height, roof type (gable vs skillion), door automation, and site works (excavation, drainage, termite barriers, bushfire BAL requirements).

How do I choose the right 3 bay garage design?

• Width and depth: If you run roof racks or have a bull bar, target 3.0 m per bay and 7.0–7.5 m depth.
• Height: 2.7 m eaves or higher for 4WDs, trades vans, or a future mezzanine.
• Roof form: Gable for airflow and looks; skillion for economical spans and water fall to one side.
• Open vs enclosed: Consider a 3 bay carport or a three bay shed with two roller doors and one open bay.
• Awning: A 3 bay shed with awning delivers shaded work area or boat/caravan cover.
• Usage: Car storage, farm machinery storage, workshop, gym, or home business—plan power, lighting, and ventilation now.
• Corrosion zone: Choose Colorbond Ultra or additional coatings if you’re within coastal spray or industrial zones.

See also: Lean-to carport guide for adding covered parking beside or in front of a triple garage.

How to get council approval for your custom shed in WA

Process highlights for council-approved sheds WA:

1. Confirm planning requirements: setbacks, heights, site coverage, driveway widths.
2. Obtain site plan, elevations, and AS/NZS 1170.2 wind region assessment (N or C/D).
3. Engineering certification by a WA-registered practitioner for portal frames, footings, and hold-downs.
4. Lodge a Building Permit (BA1 owner-builder or BA2 via a registered builder) to your local council/shire.
5. On completion, arrange inspections as required and obtain occupancy/certificates where applicable.

Added 2024 WA wind-rating compliance notes: Many Perth metro sites are N2–N3. Coastal and hilltop locations may need N4 or higher; the North West can be Region D (cyclonic). Your engineering and roller doors must match the site’s design wind speed.

Other states at a glance

• QLD: cyclone-rated sheds QLD require Region C/D design north of Tropic of Capricorn and along exposed coasts. Council approval often needs RPEQ engineering and wind-lock roller doors.
• NSW: Some Exempt Development paths exist for certain rural sheds NSW, but most triple garages still need a Complying Development or DA/CC depending on size and zoning.
• VIC: Building Permit via a registered building surveyor; bushfire BAL ratings may apply in regional and peri-urban areas.

Always check your local council rules. National Construction Code (NCC 2022) and AS/NZS 1170.2 govern structural wind actions; AS/NZS 3500 for plumbing, and energy/insulation guidance from energy.gov.au.

Wind ratings and structural engineering for triple garages

Australia uses AS/NZS 1170.2 wind regions and terrain categories:

• Non-cyclonic: N1–N6 (common in southern states and inland)
• Cyclonic: C1–C4 (QLD coast, NT, and WA north-west including Karratha/Port Hedland)

Engineering changes with higher ratings: heavier portal frames, tighter purlin/girt spacings (e.g., C-section or Z-purlins), extra roof and wall screws, diaphragm bracing, deeper footings, and wind-lock rated roller doors.

Roof styles, doors, and ventilation

• Gable roof: Classic look, good ventilation, suits regional and suburban homes.
• Skillion roof (single fall): Clean modern aesthetic, simple drainage to one side; great for 3 bay shed designs with solar.
• Flat roof carport: Most economical for a 3 bay carport, but check maximum spans and drainage capacity.

Doors: Choose between roller doors (wind-lock for cyclonic), sectional doors (premium look), or a single wide door with removable mullions. Add PA doors and windows for access and airflow.

Ventilation: Ridge vents, whirlybirds, louvre windows, and open bays under a lean-to reduce heat build-up in summer.

Keeping cool and dry: insulation and condensation control

• Anticon blanket or foil sarking under roof sheets to manage condensation
• Ceiling/roof insulation (R2.0–R3.2) and wall batts (R1.5–R2.5) for comfort and noise
• Light-colour Colorbond to improve solar reflectance in hot regions (Perth, SA)
• Vapour-permeable membranes in cold climates to prevent interstitial condensation

Use-cases and layout ideas

• Three bay garage + workshop: Two parking bays plus one bay with benches and tool storage.
• 3 bay shed with awning: Park 2 cars inside, keep a boat or caravan under the lean-to.
• Farm machinery storage: High eaves (3.6–4.2 m), wider bays for implements; suitable for rural and lifestyle blocks.
• Affordable carports for Australian homes: A 3 bay carport can later be enclosed into a 3 bay garage.

Real builds: three case studies

Perth, WA — Custom Colorbond triple garage with lean-to

9 x 7 m three car garage, 10° gable, Colorbond Surfmist, 2.7 m eaves, plus 3.6 m lean-to. N3 wind region. Automated roller doors, vermin seals, R2.0 roof blanket. Used as car storage and home gym. Example of custom Colorbond garages Perth.

Cairns, QLD — Cyclone-rated triple garage

9 x 8 m enclosed triple garage, Region C, wind-lock roller doors, heavier purlins and extra roof screw patterns per cyclone-rated sheds QLD spec. Skillion roof facing leeward. Anticon and ridge ventilation to cut humidity.

Hunter Valley, NSW — Three bay shed with workshop

10.5 x 7 m, 3.2 m eaves, two roller doors plus one high-clearance opening for a ute with ladder racks. Includes mezzanine over rear third for storage; designed to suit rural sheds NSW zoning and setbacks.

DIY shed kits vs supply-and-install

Maintenance and warranties

• Wash down external cladding every 3–6 months; monthly in marine/industrial zones
• Clear gutters and downpipes before storm season; fit leaf guards where needed
• Check door balance, springs, and seals annually; lubricate moving parts
• Recoat touch-ups early to prevent corrosion at scratches and cut edges

BlueScope warranties apply when products and details suit the exposure category and are installed to guidelines. Always file project photos and invoices for warranty proof.

Frequently asked questions

What is the standard three car garage size?

Commonly 9 x 6–7.5 m. Allow ~3.0 m per bay and at least 6.0 m depth. Taller 2.7–3.0 m eaves suit 4WDs and roof racks.

Triple garage width: what should I allow?

8.4–9.6 m overall. If you want storage along the sides, go 9.0 m+ and consider 3.2 m bays.

Do I need council approval?

Almost always for a 3 bay garage. Smaller carports may be exempt in some councils, but triple garages typically require permits. Check setbacks, heights, and stormwater rules.

Can I convert my triple garage into a granny flat later?

Not without approvals. Habitable rooms must meet NCC requirements (thermal, fire, egress, waterproofing, energy). Plan services and compliance up front if you want future conversion options.

Flat roof vs gable vs skillion?

Gable is classic and ventilates well; skillion is modern and solar-friendly; flat is economical for carports but check drainage and span limits.

5-Step Buying Guide for Custom Sheds in Australia

1. Scope: Decide on use: parking, workshop, storage, or farm machinery storage. Pick bay count, height, and doors.
2. Site + wind: Get wind region (N or C/D), soil class, BAL rating, and check sewer/stormwater plans.
3. Spec: Choose Colorbond grade/colour, roof form, insulation, 3 bay shed designs with or without awning. Local suppliers: Compare Kit Sheds Torquay for COLORBOND options that suit triple-bay spans.
4. Approvals: Confirm council pathway and engineering. Seek council-approved sheds WA or local equivalents.
5. Build: Decide DIY kit vs installed. Lock in slab, power, drainage, and timelines.

Local codes, climate, and further reading

• Bureau of Meteorology: wind and cyclone regions map – BoM climate data
• HIA: Outdoor structures and 2025 renovation trends – HIA resources
• CSIRO: Building in coastal and bushfire-prone areas – CSIRO advice
• Australian Steel Institute: Steel framing design guidance – ASI publications

References: 2025 Australian Steel Market Outlook; 2025 HIA Outdoor Structures and Home Improvement Report; NCC 2022; AS/NZS 1170.2. Local council rules always prevail.

Who is this guide for?

Australian homeowners, renovators, and property investors comparing a 3 car shed, 3 bay garage, or three bay shed in metro and regional areas, including steel sheds Perth, custom carports Melbourne, and rural sheds NSW.

Ready to design your triple garage?

Tell us your preferred footprint (e.g., 9 x 7 m), eave height (2.7–3.6 m), roof type, and whether you want a 3 bay shed with awning. We’ll return an engineered, council-ready specification tailored to your wind region and budget.

Compliance note: Designs are engineered to NCC 2022 and AS/NZS 1170.2 with site-specific wind region (N/C/D) and terrain category, including options for cyclone-rated sheds QLD and coastal WA. Added coastal corrosion and maintenance guidance for long-term performance.