The short answer is 1 in 5, which is 20%, or about 11 degrees. That's the usual maximum for a residential driveway in Queensland.
You're allowed 1 in 4 (25%, about 14 degrees), but only if the steep section stays short and is eased at both ends.
The numbers, three ways
Your builder says ratios, you'll see percentages, some sources use degrees. Same number.
| Ratio | Percentage | Degrees | Meaning |
|---|---|---|---|
| 1 in 4 | 25% | 14.0° | Steepest allowed, short runs only |
| 1 in 5 | 20% | 11.3° | The standard maximum |
| 1 in 6 | 16.7% | 9.5° | Comfortable |
| 1 in 8 | 12.5% | 7.1° | Transition grade |
| 1 in 20 | 5% | 2.9° | Near flat |
Divide 1 by the second number for the percentage. 1 ÷ 5 = 20%. Bigger second number, flatter driveway.
When 1 in 4 is allowed
NMP 1.1 of the Queensland Development Code offers two acceptable solutions. A 1 in 5 maximum, or 1 in 4 subject to conditions.
Those conditions are where drawings get knocked back:
- The length steeper than 1 in 5 must not exceed 6 metres.
- A transition is required at each end of the steep section.
- Each transition must be at least 1 metre long and no steeper than 1 in 8.
On a short block those conditions bite first. A 7-metre run at 1 in 4 fails however gentle its transitions. More in what the QDC says about driveway gradients.
The maximum is rarely the problem
Your driveway can sit under every limit and still ground a car. The damage comes from how *abruptly* the slope changes, not how steep it gets.
A sharp break from flat street to 1 in 4 drops your front bumper while the rear wheels are still level. Spread it over a metre or more and the car rides through untouched.
That's what the transition rule is for, and why rate of grade change beats the headline number.
Checking your own
- Measure the height difference between the street boundary and the garage floor.
- Divide it by the driveway length. A 1.5 m rise over 8 m is 1 in 5.3.
- Find the steepest section, not the average. That's the one that governs.
- If any part exceeds 1 in 5, measure that run. Over 6 m and it doesn't meet the concession.
- Check both ends of the steep part for at least 1 m of easing.
For councils and AS 2890.1, see driveway gradients in Queensland.
Disclaimer
General information, not advice. This summarises QDC NMP 1.1 as published rather than reproducing it. NMP 1.1 is a non-mandatory part of the code, and local planning schemes, council standard drawings and conditions on individual approvals may require something different. Confirm with your council or a qualified certifier.
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