What size is a three car garage in Australia?

A true three car garage (triple garage) gives three clear vehicle bays plus circulation, door swing and storage. Standard kit footprints and custom builds vary by intended use (cars only, workshop, mezzanine or machinery). Choose bay width, depth and eave height to suit vehicles and storage needs.

Choosing bay width by vehicle type

• Sedans/city cars: 2.6–2.8 m bay width (allow 0.3–0.4 m clearance each side).
• SUVs/large sedans: 3.0–3.2 m bays recommended — especially with roof racks or side steps.
• 4WDs/work utes: 3.2–3.5 m bays for ladder racks, bull bars and easy entry.

Shelving, racking and aisle space

If you plan shelving along walls, allow 300–600 mm per side plus a minimum clear aisle of 600–900 mm between parked vehicles and benches. For safe circulation, depth of 7.0–7.5 m is common when benches or racking are fitted behind vehicles.

Mezzanine and high-eave examples

• 9 x 7 m + mezzanine (rear third): eave height 3.2–3.6 m, mezzanine clear headroom 2.0 m, mezzanine footprint ~3.0 x 7.0 m (storage only).
• Farm machinery/high eaves: 12 x 9 m footprint with eaves 4.0–4.5 m for tractors/implements and wide bay modules (4.0–5.0 m).

Design tip: For future flexibility, specify 3.2 m bays and 3.0–3.6 m eaves if budgets allow — this handles most SUVs, roof racks and a simple mezzanine.

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

Perth has hot, dry summers and coastal salt exposure in many suburbs. Choose cladding and coatings with corrosion resistance, good reflectivity and warranties suitable for marine zones. Colorbond is the common choice; Zincalume remains an economical alternative for inland sites.

Colorbond grades and coastal guidance

BlueScope offers standard Colorbond and Colorbond Ultra (enhanced corrosion resistance). Ultra or marine-grade finishes are recommended for properties within close proximity to breaking surf. Typical guidance suggests Ultra for sites within ~100–200 m of exposed surf — verify against BlueScope guidance for your address.

Learn more: Colorbond vs Zincalume comparison and see our local builds in custom Colorbond garages Perth.

Corrosion zones & marine-grade explanation

Australian corrosion exposure categories (AS/NZS guidance) classify sites by salt spray intensity and pollutant exposure. Marine-grade steel implies extra protective coatings or Colorbond Ultra finishes and increased inspection frequency. For detailed exposures, request a site-specific corrosion assessment from an engineer or coatings specialist.

Reference & warranty: See BlueScope’s Colorbond warranty and technical guides for coastal installation requirements: BlueScope.

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

Pricing varies widely by region, wind rating, site works and specification. Below are indicative 2025 figures (ex GST) and a short methodology note: Pricing compiled from supplier quotes, HIA 2025 market data and installer estimates; request three quotes for your site.

Cost breakdowns (indicative)

• Supply-only kit (Colorbond, 9 x 6–7 m, non-cyclonic): $12,000–$25,000.
• Installed turnkey (9 x 7 m): slab, erect, doors, basic electrics: $28,000–$60,000 depending on region and site works.
• Concrete slab (100–125 mm, mesh, edge beam): $120–$220/m² depending on access and soil class.
• Cyclone upgrade (Region C/D): +15–35% uplift for frames, doors and anchor systems.
• Extra site prep (rock excavation, retaining, stormwater): variable — allow contingency $2,000–$20,000.

Worked example — cyclone uplift

Base installed price: $35,000. Cyclone uplift 25% => $35,000 × 1.25 = $43,750. Add remote access premium or site works as required.

Perth metro vs remote regional examples

• Perth metro installed 9 x 7 m (N2–N3): $32,000–$48,000 — standard slab access, typical transport.
• Remote regional (river access, poor access): $45,000–$75,000 — higher transport, crane and labour uplift.
• DIY kit owner-build (no slab or electrical): save ~25–40% on installed price but add tools, plant hire and permit costs.

Source note: HIA Outdoor Structures 2025, supplier quotes and regional installer data inform these ranges. Final price always depends on site-specific engineering, wind region and council requirements.

Choosing the right triple garage design

Design flow: decide purpose → choose bay width/depth → pick roof form → select doors and ventilation → specify insulation and access. Use the flow to scope a specification before requesting quotes.

Decision flow checklist

1. Purpose: parking, workshop, business or mixed use (affects eave height and electrical needs).
2. Vehicles & clearance: choose bay width per vehicle type (see sizing section) and eave height for roof racks/mezzanine.
3. Roof form: gable for looks/ventilation, skillion for solar, flat for economical carport conversions.
4. Doors: roller, sectional or wind-lock roller for cyclonic regions.
5. Ventilation & insulation: ridge vents, whirlybirds, and R-value based on climate zone.

Layout suggestions (text floor plans)

2-car + workshop: 9 x 7 m with two 3.0 m bays left, 3.0 m rear workshop bench area. 3 cars + mezzanine: 10.5 x 7 m footprint, rear mezzanine 3 x 7 m at 3.2 m eaves.

Explore sample options and plan templates at our three bay shed designs page before you brief suppliers.

Getting council approval for custom sheds in WA (and other states overview)

Below is a practical, step-by-step approvals guide and state overview. Timeframes are indicative and vary by council.

Step-by-step approvals (typical timeframes)

1. Pre-check (1–2 weeks): Confirm zoning, setbacks, maximum site coverage and planning overlays with council.
2. Design & engineering (1–3 weeks): Prepare site plan, elevations, and an AS/NZS 1170.2 wind region assessment.
3. Lodge building permit (2–6 weeks): BA1 (owner-builder) or BA2 (registered builder) process in WA; supply required documentation.
4. Construction inspections (during build): Council or private certifier inspections as required.
5. Completion certification (1–2 weeks after final inspection): Occupancy or completion certificate where applicable.

When permits are NOT required (high-level)

Some councils exempt small carports or sheds under threshold sizes and heights. Examples: low-height carports under a specified site coverage or setback — but triple garages are commonly over exempt thresholds. Always check your local council portal for exact thresholds.

WA specifics (council-approved sheds WA)

In WA, provide a site plan, structural engineer’s drawings for portal frames and footings, and lodge BA1/BA2 permit applications with your local council. For more detail see the WA Building Commission and local council pages. For QLD cyclone design see cyclone-rated sheds QLD.

Other states at a glance

• QLD: RPEQ engineering often required for cyclonic regions; refer to regional council building guides.
• NSW: Some rural sheds may fit Exempt Development; otherwise DA/CC or Complying Development applies — see rural sheds NSW.
• VIC: Building Permit via building surveyor; consider BAL (bushfire attack level) assessments in peri-urban areas.

Compliance resources: National Construction Code (NCC 2022) and AS/NZS 1170.2 wind standards. For step-by-step help, review our 5-step buying checklist below.

Wind ratings and structural engineering for triple garages

Wind design follows AS/NZS 1170.2 which defines wind regions (N1–N6, C1–C4 for cyclonic). Site classification, terrain and shielding set design wind speeds; higher ratings increase structural requirements.

Wind region mapping (high-level)

• Non-cyclonic regions: N1–N6 common across southern and inland Australia (Perth metro often N2–N3).
• Cyclonic regions: C1–C4 apply in coastal QLD, NT and NW WA (e.g., Karratha/Port Hedland areas).

Engineering implications

Higher wind ratings typically require: heavier portal frames, closer purlin/girt spacing, diaphragm bracing, increased screw counts, wind-lock roller doors and deeper or reinforced footings. Typical footing depths vary by soil class but often range 300–600 mm for slab edge beams; deepened piers or reinforced pads may be needed in poor soils.

Doors: Wind-lock rated roller doors are essential in cyclonic zones — expect door upgrades to add roughly 5–12% to the door & installation cost depending on size and automation. See the cost section for uplift examples.

For site-specific assessment, follow the AS/NZS 1170.2 wind region assessment and engage a registered structural engineer.

Roof styles, doors, and ventilation

Roof style pros & cons

• Gable: Good ventilation and classic look; slightly more complex ridge framing; suitable for solar on dual pitches.
• Skillion: Modern, simple drainage to one side; ideal for large single-run solar arrays and economical framing.
• Flat roof carport: Lowest visual profile and cost but requires careful drainage and reduced spans.

Solar panels and roof choice

Skillion and gable roofs both suit solar installations. Skillion offers unshaded single-aspect orientation and simpler inverter runs.

Door selection matrix

Ventilation options and placement

Ridge vents and gable vents provide passive flow. Whirlybirds (rotating ventilators) are effective in hot, still summers. Place vents at high points: ridge and gable ends, and include louvre windows or powered extraction for workshops with fumes.

Keeping cool and dry: insulation and condensation control

Condensation occurs when warm moist air contacts cool metal surfaces. Use sarking, foil blankets and appropriate insulation to reduce condensation and internal temperature swings.

R-value recommendations by climate

• Perth / Mediterranean coast: R2.0–R3.0 roof insulation plus foil sarking to reflect heat.
• Tropical (Cairns region): Use vapour-permeable membranes and mechanical ventilation; insulation R1.5–R2.0.
• Temperate inland (Hunter Valley): R2.5 recommended for thermal comfort and condensation control.

Installation tips

• Install continuous foil sarking under roof sheets to create a condensation barrier and radiant reflector.
• Use high-quality roof blankets (Anticon style) tucked into purlins with ventilation paths.
• Insulated panel roofs (sandwich panels) reduce internal temperatures by up to 10°C and cut condensation risk.

Use-cases and layout ideas for triple garages

Triple garages are versatile: pure car storage, mixed workshop, boat/camper storage, home business or farm machinery. Below are text-based floor plan ideas you can adapt.

Layouts (text plans)

• Two-car + workshop: 9 x 7 m — bays 1–2 for cars, bay 3 fitted with benches and roller door or personnel door.
• Car + caravan + small workshop: 10.5 x 7 m — middle bay widened to 3.6 m for caravan access, rear bench space.
• Boat/camper storage: 11 x 7.5 m — one high-clearance bay (3.4–3.8 m eaves) plus two standard bays.

If you plan a future conversion to a home business or granny flat, pre-run services (electrical, greywater planning) and set aside space for additional insulation and doors.

Real builds: case studies from Perth, Cairns, and Hunter Valley

DIY shed kits vs supply-and-install

Choose DIY only if you have the experience, time and access to plant. Supply-and-install is best for compliance, warranty and single-point responsibility.

Owner-build readiness checklist

• Experience with steel frame erection, riveting and cladding.
• Access to lifting gear (telehandler or crane for large spans).
• Ability to coordinate slab contractor, electrician and plumber.
• Engineering drawings and permit-ready documentation.

Compare options in our DIY shed kits vs installed guide and check warranty implications on BlueScope pages.

Maintenance and warranties

12‑month maintenance schedule

• Monthly: clear leaves from gutters and check door seals.
• Quarterly: wash cladding in coastal areas; check fasteners and gutters for corrosion.
• Annually: service doors, inspect cut edges and touch up paint as required.
• Every 5 years: professional inspection of structural fixings in marine/industrial zones.

How to make a BlueScope claim — practical checklist

1. Gather purchase invoices, installer details and dated photos of the issue.
2. Confirm the exposure category and installation details meet BlueScope requirements.
3. Contact the supplier/installer first, then BlueScope if unresolved.
4. Keep records of all correspondence and repair quotes.

Read BlueScope warranty terms: BlueScope warranties. Note: warranties often require correct cut-edge treatment and installation to technical guides.

Frequently asked questions

See the FAQ block below for full answers and next steps.

5-Step Buying Guide for Custom Sheds in Australia

Follow this checklist to prepare for supplier quotes and council paperwork.

1. Scope & use: Document purpose, daily vehicle types, storage, workshop equipment and any business use. Add desired bay widths, eave height and mezzanine needs.
2. Site info: Collect site plan, orientation (north arrow), address, photos, access, soil notes and slope. Get your wind region from BOM and note any BAL/bushfire or heritage overlays.
3. Spec sheet to issue: Wind region, bay widths, footprint, eave height, roof form, Colorbond grade & colour, door types, insulation, electrical load and required engineering.
4. Supplier questions: Ask about lead time, inclusions (gutters, flashings), warranty steps, engineer certification and who lodges the permit. Request a sample contract and payment schedule.
5. Approvals & build: Confirm council pathway, who lodges BA1/BA2, inspection schedule and defect liability period. Keep a pack of all documents for warranty claims.

Use our council-approved sheds WA page for WA-specific filing examples and links to state portals.

Local codes, climate resources, and further reading

• Bureau of Meteorology: wind and cyclone regions map — BoM climate data
• National Construction Code (NCC 2022) summary — NCC 2022 (ABCB)
• AS/NZS 1170.2 wind actions overview — AS/NZS 1170.2
• BlueScope Colorbond warranty & technical guides — BlueScope
• HIA Outdoor Structures 2025 report — HIA
• CSIRO guidance on coastal building practices — CSIRO
• Australian Steel Institute design guidance — ASI

Sources & further reading: HIA 2025, BlueScope technical pages, AS/NZS standards and BOM wind region maps. Always check local council rules for your site.

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 and local carport solutions.

Ready to design your triple garage?

Request a free site appraisal and engineered specification — submit your footprint, wind region and photo/plot plan. We’ll provide a council-ready quote and options (DIY kit or supply & install).

Request a free appraisal

Legal disclaimer: This guide is general information only. Obtain site-specific engineering, soil tests and local council approvals before ordering or constructing a shed. We accept no liability for build outcomes based solely on this guide.

Frequently Asked Questions

1. What are the standard dimensions of a three car garage in Australia?

Standard footprints include 9 x 6 m, 9 x 7 m and 10.5 x 7 m. Internal clearances typically allow 2.6–3.2 m per bay and 2.7–3.6 m eave heights for taller vehicles or mezzanines. For tailored advice, consult the sizing section above or request a site appraisal.

2. How much does a triple garage cost to build in 2025?

Installed turnkey triple garages typically range $28,000–$60,000+ (ex GST) depending on slab, doors, wind rating and site prep. Supply-only kits may be $12,000–$25,000. For a site-specific estimate, see the costs section and request three local quotes.

3. What materials are best suited for three car garages in coastal WA?

Colorbond, particularly Colorbond Ultra or specified marine-grade finishes, is recommended within coastal exposure zones; light colours help reflect heat. Zincalume is cost-effective inland but may corrode faster near salt spray. Review BlueScope guidance and our materials section.

4. When do I need council approval for a triple garage in Australia?

Most triple garages require council approval (building permit and possibly planning). Exemptions are rare for three bays. Timeframes vary but expect 2–8 weeks for permits. See the approvals section and your local council portal for thresholds and forms.

5. What are the differences between Colorbond steel and Zincalume for garages?

Colorbond is painted with weather-resistant finishes and available in Colorbond Ultra for marine environments; it offers better aesthetics and heat-reflective colours. Zincalume is an aluminium-zinc alloy coated steel, cheaper but less decorative and potentially higher maintenance near coasts. See our comparison page.

6. How do wind ratings affect the design and cost of a three bay shed?

Higher wind regions (AS/NZS 1170.2 C1–C4 or elevated N categories) require stronger portal frames, closer purlin spacing, upgraded fixings and wind-lock doors. Expect a 15–35% cost uplift for cyclone-rated designs; see the wind ratings and cost sections for worked examples.

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

Conversion is possible but requires planning and building approvals to meet NCC habitable space rules (thermal, fire, egress, services). Pre-planning for services and higher eaves helps; consult the approvals and design sections and your local council before building.

8. What are the pros and cons of DIY shed kits versus professional installation?

DIY kits save money but require steel erection skills, lifting gear and permit management; incorrect installation can affect warranties. Supply-and-install costs more but simplifies approvals, warranty claims and engineering. See our DIY checklist and warranty guidance for next steps.