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) .
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.
To go from a Flat slab (gradient 0%) to a gradient of 15% a transition section would be 7.5% ( [0% + 15%] / 2 )