Size the carport around open doors, posts and tomorrow's vehicle

For one everyday car, aim for 3.5 m clear width and 6 m clear length. That aligns with the practical covered-space dimension used in Victorian residential planning guidance and gives enough room to open a door without leaning against a post. On an unrestricted side, 3.2 m can work for a compact vehicle. Between a house wall and posts, 3.5 m is far more forgiving.

For two cars side by side, 5.5 m clear internal width is the minimum planning benchmark worth remembering. We usually recommend a nominal 6 x 6 m structure as the starting point, then widen it to 6.5 or 7 m when both vehicles are SUVs, a child seat needs regular access, or a wall sits along one side. An extra 500 mm costs much less during design than moving posts after everyone discovers the passenger door cannot open.

Length deserves the same care. A typical 4.7 to 5 m vehicle needs space ahead and behind for walking, a towbar and rain protection. Six metres is sensible. A dual-cab ute with towbar can approach 5.5 m, so 6.5 m is more comfortable. If the roof ends exactly over the bumper, angled rain and summer sun still reach the vehicle.

A complete single steel carport commonly runs $5,500 to $9,500 across Pakenham in 2026. A double commonly runs $8,000 to $15,000. The lower end assumes straightforward access, flat Colorbond roofing, standard engineering and no planning complication. Gables, insulated panels, difficult excavation, high clearance and custom colours move the result upward.

A double uses roughly twice the roof area and slab, but not twice the whole budget. Both jobs need a site visit, drawings, engineering, surveyor involvement, mobilisation, drainage planning and inspections. That makes the marginal square metre cheaper on the larger roof. As a rough planning allowance, a standard slab can contribute $110 to $170 per m², roof and steel complexity varies widely, and approval plus professional documentation can contribute $1,200 to $3,000 per project.

Widening a double from 6 to 6.5 m can add roughly $1,200 to $3,000 once longer beams, extra roof area and slab are counted. Raising the clear height for a caravan can add $1,500 to $4,000 because posts, bracing, wind actions and possibly planning impact all change. It is poor value to save $1,500 on size and then park a $60,000 vehicle with one door unusable.

Compare these figures with the site's full 2026 pricing guide. Ask each builder to state external roof dimensions, clear internal dimensions and slab area separately. Three different numbers described as “6 x 6” can otherwise produce three different finished structures.

A useful single carport is normally well over Victoria's narrow 10 m² freestanding Class 10a permit exemption, so plan for a building permit unless a building surveyor confirms otherwise. Larger roofs also make setbacks, private open space, site coverage, easements and drainage more important. A carport forward of the house or on an overlay-affected property may need Cardinia Shire planning approval before the building permit. Read the local permit guide before locking in a kit size.

Allow 6 to 12 weeks for a routine design, engineering, approval, fabrication and build sequence. Site work is often 3 to 5 days. February to May is a useful local window because excavation is less likely to be in saturated winter clay and concrete avoids the harshest summer curing conditions. More season detail is in the Pakenham build timing guide.

A good quote states the proposed post grid, clear dimensions, highest and lowest beam clearance, roof overhang, vehicle assumptions and drainage connection. It also identifies whether the slab, permit, engineering, service location, excavation spoil and final certificate are included. Those details separate a finished parking space from a roof kit that creates six extra invoices.