Driveway Slope
If your vehicle is a specially adapted off-roader like this Land Rover then driveway slope is not going to be an issue.
For the rest of us it is something you should be aware of.
If you have lowered your suspension, installed a body kit, or have a sports car then it could be critical.
Maximum and Minimum Slopes
For proper drainage of the driveway you will need a minimum gradient of 1 in 100 (1%, or 10 mm per metre)
This could be either along the driveway or cross fall.
Local Authorities rules on maximum slopes do vary (so check) but typical gradients are:
- Public areas 1 in 20 (5%, or 50mm per metre) in the public footpath area or
- Within the property boundary 1 in 4 (25%, or 250mm per metre) .
Transitions
At the top of slopes there is a risk of the underside of the vehicle grounding.
At the bottom of the slope the front or rear of the vehicle can ground.
For standard vehicles a change in gradient of 12.5% is typically the point where problems can start to occur. (For lowered vehicles it may be much less than 10%)
A typical way to minimise the risk is to have a transition section of around 2m long between the two gradients.
For example
To go from a Flat slab (gradient 0%) to a gradient of 15% a transition section would be 7.5% ( [0% + 15%] / 2 )