Double Car Port in Australia: Dimensions, Design, Cost, and Council Approval

Determining the Ideal Double Car Port Dimensions

Choosing the right footprint and clearances ensures functionality, street appeal, and compliance. In practice the “sweet spot” for most Australian households is a 6×6 m clear-span footprint, but site constraints, vehicle types and intended uses (storage, boat, caravan) change the brief. Key dimensional terms:

• Clear span: The unobstructed width between the inside faces of supporting posts—critical for door opening and turning (example: a 6.0 m clear span uses a portal frame or conventional posts at ~6.2 m centres).
• Clear height: The vertical distance from finished ground level to the underside of the roof or rafters—typical residential clear heights are 2.4–3.0 m depending on vehicles.
• Door clearance: Side clearance per car door to allow easy entry/exit—recommend 900–1,200 mm per side where space allows.
• Carport footprint: Overall outside-to-outside dimensions (roofline) used for planning and council lodgement.

Typical Dimensions by Vehicle Type

Use these practical targets when sizing your carport. Allow for bull bars, roof racks and trailer coupling where relevant (clearances are per vehicle unless noted):

• Sedans / small SUVs: aim for 5.8–6.0 m clear span × 5.5–6.0 m depth, clear height 2.4–2.7 m. Door clearance: 900–1,000 mm recommended.
• Large SUVs / dual-cab utes: 6.0–6.5 m span × 6.0–7.0 m depth, clear height 2.7–3.0 m to accommodate roof racks.
• Boat / caravan owners: 6.0–7.5 m span × 7.0–9.0 m depth, clear height 3.0–3.6 m to suit trailers and overhead gear.

Walkway clearance guidance: keep 800–1,000 mm clear on at least one side for safe egress and storage. When block width is limited, consider an attached carport to the dwelling to maximise covered area; freestanding gives flexibility and easement advantages.

Popular Car Port Sizes in Australia

Common footprints (and when to pick them):

• 6 × 6 m: Standard twin-car footprint for two sedans or small SUVs — best balance of cost and usability.
• 6 × 7 m: Extra depth for Utes with trays, tow bars or rear storage; recommended if you carry bikes or need a small rear storage zone.
• 6.5 × 6.5 m: Extra elbow room for larger SUVs and easier door opening — useful for families with prams and child seats.

Example layout — 6 × 6 m portal frame (two-post front, two-post rear): posts at the corners, 5.9 m clear span between inner faces, 2.7 m clear height. Example layout — attached 6 × 7 m: attach to fascia using engineered bracket, posts on outer line, allow 600–900 mm drip edge clearance to house walls.

Best Materials for Australian Climate with a Focus on Perth

Perth’s hot summers and coastal exposures require corrosion-aware choices and sun-smart colours. Use materials and fixings suited to your warranty zone and local council requirements.

BMT, Coatings and Fixings

Recommended Base Metal Thickness (BMT): for most non-cyclonic residential carports 0.42 BMT roofing sheeting is common; in higher-wind or coastal/cyclonic areas specify 0.48 BMT minimum (source: BlueScope technical notes; see BlueScope warranty map). Use hot-dip galvanised or stainless fixings in splash zones where salt spray is expected. For coastal houses within close proximity to surf, prefer stainless fasteners for flashings and cut-edge protection.

Colorbond vs Zincalume Selection Guide

Both materials are widely used; choice depends on aesthetics, thermal performance and warranty zone. See our dedicated guide on Colorbond steel for sheds for full details.

Warranty & zones: always check BlueScope’s warranty zone map for your postcode (warranty periods and required maintenance differ by distance to coast). For more on warranties and corrosion, refer to the BlueScope warranty information (external link).

When to Use Zincalume

Choose Zincalume for budget-sensitive projects or non-street-facing carports. Zincalume has an excellent base corrosion resistance but is less forgiving for visible cut edges and requires regular maintenance near marine environments. For coastal or splash-zone installs, upgrade fixings to stainless and seal cut edges.

Design Options for Functionality and Value

Design choices affect upfront costs and long-term performance. Focus on drainage, structural members, insulation and services routing before pouring footings or slab.

Roof Styles, Drainage and Lighting

Flat roofs suit modern homes and are cheaper but need adequate fall and larger gutters to avoid ponding. Gable roofs add street appeal and natural ventilation. Specify quad or box gutters with 90 mm downpipes to stormwater; in council-restricted areas a soakwell may be accepted. For electrical runs, plan conduit paths and locate service entry points prior to slab work—typical conduit depth for underground runs is 300 mm below finished surface unless in vehicle areas where a deeper path is required.

Insulated Panels & Thermal Performance

Insulated roof panels (sandwich panels) reduce radiant heat and rain noise compared with single-skin sheeting. Supplier tests show typical under-roof temperature reductions vary by insulation thickness, colour and ventilation—supplier data (e.g., Thermatech product literature) should be requested for the specific configuration. Do not rely on an absolute reduction figure without test data; instead ask for performance figures for your chosen colour and insulation R-value.

Posts and Structural Members

Galvanised RHS posts (e.g., 100×100 or 150×100 depending on span and wind rating) and powder-coated beams provide long life and a neat finish. In higher corrosion zones, specify hot-dip galvanised or stainless where exposed to salt. Portal frames are recommended where a full clear span is desired to avoid central posts.

Upgrade Cost Examples

• Insulated roof panels: typical premium delta +$2,000–$4,000 (depending on size and R-value).
• Powder-coating powder-finish posts/beams: +$300–$1,000 depending on finish and extent.
• Gutter and stormwater connection to mains: +$500–$1,200 depending on proximity and council requirements.

Engineering, Wind Ratings, and Compliance Requirements

Design must comply with AS/NZS 1170.2 (Wind actions) and AS/NZS 4600 (Cold-formed steel structures). Engineering ensures the structure is sized for the design wind speed at your site and for the correct importance level.

What AS/NZS 1170.2 and AS/NZS 4600 Mean for Your Carport

Terrain category describes the surrounding roughness (open ground vs suburban) and changes calculated wind pressures. Importance level (1–4) reflects the building’s consequence of failure (residential carports are typically Importance Level 2). Both inputs alter design wind speed and load cases. AS/NZS 4600 covers section properties, member checks and cold-formed steel detailing used in portal frames and purlin design (Australian Steel Institute guidance summarises how to apply these standards).

Reading Wind Rating Maps (N and C classifications)

Non-cyclonic areas are grouped N1–N4; cyclonic regions use C1–C4. Higher numbers mean increased design wind speeds and more robust fixings. For example, many Perth suburbs fall into N2–N3, while exposed coastal escarpments may be N4. Tropical north QLD towns fall into C classifications and demand cyclone-grade connections. Provide your engineer with the exact site coordinates so they can determine the correct map zone and factors (AS/NZS 1170.2 requires site-specific inputs).

Practical Checklist for an Engineering Pack

• Site plan with contours, finished floor level and nearby obstructions.
• Soil class or classification (if available) and any bore log or geotechnical notes for unusual soils.
• Specified wind classification (map zone) and terrain category assumptions.
• Detailed drawings: elevations, sections, connection details and footing specs.
• Footing types: examples include 450 mm dia × 900 mm deep bored piers with M16 anchor bolts for medium soils; slab anchorage or pad footings for other conditions—engineer to specify depth and reinforcement based on soil and frost if required.
• Hold-downs and washers: size and specification per engineer; in cyclone-prone areas use multiple hold-downs per post and larger washers per AS/NZS guidance.

To request certification, request engineering certification from your supplier during quoting so the engineer account number and scope are clear on the proposal.

How to Obtain Council Approval in WA and Beyond

Approval pathways differ by state. Below are practical steps and thresholds—always confirm with your certifier or local council.

Western Australia (WA)

1. Check the R-Codes and local planning policies for setbacks and street-facing materials (council websites list local variations).
2. Determine if the carport is exempt development (usually small, low-height structures meeting specific setbacks) or needs a building permit.
3. Lodge a DA or building permit with site plan, elevations, engineering pack and stormwater management details.
4. Include signed engineer’s certificate for wind rating and footings if required; arrange inspections as per certifier schedule.

See local council pages for exact thresholds. For WA-specific advice, consult providers of council-approved sheds in WA.

Victoria (VIC)

Victoria allows exempt development for certain small structures (size, height and setback limits apply). Where exempt development does not apply, a building permit is required. The Victorian Building Authority (VBA) publishes clear guides—check the VBA site and your local council.

New South Wales (NSW)

NSW offers Complying Development Certificates (CDC) for standardised builds that meet the rules; otherwise a DA is required. A CDC can be faster but has strict criteria, so confirm early with a certifier.

Queensland (QLD)

QLD requires cyclone detailing in northern zones and often needs certified engineering documentation lodged with the permit. If in a cyclonic zone, ensure your engineer uses C-classification inputs and that the installer is experienced with cyclone connections. See cyclone-rated sheds QLD for local partners and guidance.

Tip: Local planning staff or private certifiers will confirm whether your project is exempt, complying, or requires a full DA. Always get written confirmation before ordering materials.

DIY Kits vs Custom-Built Double Car Ports

Both DIY kits and custom supply-and-install options can be compliant and engineered. The right choice depends on your skillset, access, site complexity and whether you require cyclone-rated detailing.

Decision Flow & Site Complexity Checklist

Choose DIY if the site is level, easily accessible, local regs are simple and you have trades skills. Choose custom-built if you have sloping blocks, underground services, limited access for cranes or require cyclone-rated engineering. For cyclonic zones, only certified engineered kits or installer-supplied engineered builds are recommended.

Real-World Case Studies from Australia

Case study 1: Custom Colorbond double carport in Perth (6 × 6 m)

Use-case: Two SUVs and surfboard storage. Spec: Gable roof, COLORBOND Surfmist, 0.42 BMT sheeting, galvanised 100×100 RHS posts, portal frame delivering a 5.9 m clear span and 2.7 m clear height. Engineering: WA-registered engineer (report included with permit) specifying N3 wind inputs; footing spec: 450 mm diameter × 900 mm deep cast piers with M16 hold-down anchors. Timeline: Site survey (day 1), footing excavation & pour (day 7), structure install (day 21 after cure). Outcome: two-day install, planning approval obtained without neighbourhood objections.

• Key takeaways: Portal frames deliver a clean street look and full clear span; allow time for footings cure before erection.

Case study 2: Cyclone-rated double carport, North QLD (6 × 7 m)

Use-case: Dual-cab ute and boat trailer. Spec: Flat roof, 0.48 BMT, upgraded purlins and cyclone tie-downs with multiple hold-down washers; region classified C2. Engineering: cyclone-certified engineer supplied full connection and footing drawings; footings were deeper piers with reinforced concrete and multiple M20 hold-downs per column. Timeline: design and permits (3 weeks), deep pier works (1 week), structure install (3 days). Outcome: final inspection passed; strong performance in severe storms.

• Key takeaways: Cyclone areas require larger BMT, more hold-downs and careful logistics—factor additional time and cost.

Case study 3: Wide-span freestanding carport for machinery, rural NSW (8 × 7 m)

Use-case: Storage of tractor and implements. Spec: Portal clear-span 7.8 m, 0.48 BMT roofing, increased purlin spacing and deeper piers owing to expansive soils. Engineering included soil assessment and modified footing design. Outcome: successful installation with larger-than-average post sizes to resist uplift and bending from wind and equipment loads.

• Key takeaways: Rural and farm structures often require bespoke footing solutions—include geotech or soil notes in the engineering brief.

Cost Guide for Double Car Ports in 2025

Cost drivers include material selection, BMT, finishes, engineering, footings and access logistics. All figures are indicative and based on market conditions as of March–May 2025 (industry sources: Housing Industry Association, Australian Steel Institute).

Component Cost Breakdown (Indicative)

• Supply of standard 6×6 gable kit (0.42 BMT COLORBOND): $3,500–$6,000
• Engineering pack and certification: $600–$1,200 (or bundled in supply+install quotes)
• Footings (standard bored piers, per pier & labour): $150–$350 each depending on depth and access
• Supply & install labour (per 6×6): $3,000–$6,000 depending on region and complexity
• Council fees & permits: $200–$1,500 depending on state and valuation

Sample Itemised Quote — Standard 6×6 Gable (supply & install)

Supply COLORBOND gable roof 6×6 (0.42 BMT): $4,200; Engineering & drawings: $900; Footings & reinforced piers (4): $1,200; Labour & install: $3,200; Gutters & downpipes: $300; Permits & inspections allowance: $500; TOTAL ESTIMATE: $10,300 (ex. GST) — adjust for site, wind rating and finish.

Note: Cyclone-rated upgrades typically add $1,500–$4,000 depending on classification and number of hold-downs. Insulated panels add $2,000–$4,000 extra (size-dependent). Prices should be requested in writing and dated; see HIA and Australian Steel Institute market commentary for trends.

Climate and Site-Specific Planning Considerations

Design decisions must reflect climate and site specifics. Below are focused recommendations:

For Perth heat, choose lighter Thermatech colours to reduce radiative heat (supplier data can quantify reductions). For coastal corrosion, prefer hot-dip galvanised posts and stainless fixings within the immediate splash zone.

Step-by-Step Buying Guide for Custom Sheds

This 10-point checklist will help you progress from brief to handover:

1. Define your sizing brief (span, depth, clear height and uses) — refer to double carport dimensions.
2. Complete a site survey: levels, soil notes, services and access.
3. Select materials: COLORBOND or ZINCALUME, BMT, finishes and fasteners.
4. Ask suppliers for engineering scope and confirm engineer registration details.
5. Request an itemised quote with included permit support and estimated lead times.
6. Confirm council pathway and lodge required documents (site plan, elevations, engineering).
7. Prepare footings per engineer and arrange footing inspection.
8. Schedule structure install including crane or pickup as needed.
9. Arrange electrical works and conduit before slab/footings are poured where required.
10. Complete final inspection and obtain compliance documents and engineer sign-off.

Templated Questions to Ask Suppliers

• Are you ShedSafe-accredited and can you provide proof? (See ShedSafe membership and audit scope.)
• What is the BMT of roof sheeting and purlins?
• Do you include an engineer-signed design and certificate? (Provide engineer registration.)
• What are your lead times, warranties and exclusions?
• Can you provide itemised costs for upgrades and cyclone-rated options?

Technical Definitions and Resources

Quick references and standards:

• AS/NZS 1170.2 — Wind actions (standards summary: Standards Australia / industry guidance).
• AS/NZS 4600 — Cold-formed steel structures (design and detailing requirements).
• Australian Steel Institute — ShedSafe — accreditation program for suppliers (shedsafe.com.au).
• BlueScope / COLORBOND — warranty zone maps and Thermatech data (check BlueScope technical pages).
• BOM cyclone maps — Bureau of Meteorology cyclone region maps.