What the QDC Actually Says About Driveway Gradients

The QDC is split into Mandatory Parts (MP) and Non-Mandatory Parts (NMP). Driveways sit in NMP 1.1, which legislation doesn't reference.

Councils still reference NMP 1.1, development conditions invoke it, and certifiers use it as the yardstick when nothing more specific applies. But it's guidance rather than a statutory requirement, and a local planning scheme or approval condition often imposes something different. Check the conditions on the approval before assuming NMP 1.1 governs.

NMP 1.1 offers two acceptable solutions, the first a maximum gradient of 1 in 5.

The second is the concession that matters on steep blocks. A driveway may reach a maximum gradient of 1 in 4, provided the length steeper than 1 in 5 does not exceed 6 metres. The ends of that 1:4 section also need a change in gradient, not less than 1 metre in length and not greater than 1 in 8.

Treating 1:8 as a general rate-of-change limit is conservative, so a profile drawn that way will usually satisfy NMP 1.1. The reverse case is where drawings fail. A designer who takes 1:8 per metre as the whole requirement can miss that the 1:4 concession also caps the steep run at 6 metres and requires a transition of at least a metre at both ends, not one.

On a short, steep block those two are often the binding conditions. A 1:4 section of 7 metres doesn't comply however gentle the transitions, and an 800 mm transition doesn't comply however shallow its grade.

AS/NZS 2890.1 covers off-street parking, including residential access, and it's the other document a certifier is likely to have open. The two don't conflict, but they aren't identical, so a driveway can satisfy one while a condition on the approval requires the other.

Whichever document the approval cites is the one to design to, within the tighter of the two where they differ.

NMP 1.1 also carries a performance requirement, that a vehicle travel the length of the driveway without scraping, scratching or being damaged.

That's why the transition rules exist. A profile that satisfies every number on the page can still ground a long-overhang vehicle. Why a minimum-length transition isn't always enough covers what to do where the site allows more room.

A driveway long section is easier to assess when its numbers are stated rather than scaled off the page.

• The boundary RL and the finished garage slab RL
• Each zone's length, and its gradient expressed as a ratio
• The location and length of every transition
• The resulting platform level at the garage

DrivewayIQ holds every zone to the limits of the rule pack selected for the job, so the rate-of-change limit isn't fixed. It's 1:8 under our AS 2890.1 pack and 1:12 under our Brisbane one, matching the council's published figure. The measured rate of change is reported next to the limit that applies, because 1:8 read on its own looks fine to someone whose council requires 1:12. Select the right pack, and confirm the figure your council publishes before treating a pass as compliance.