I'm drawing plans for a planning application to put a drive way into my garden. I'm considering a 6m level parking bay and a ramp of 2.5m long falling 0.54m down to the road. (all 3m wide).
If my sums are correct that's a gradient of 21.6% or 1 in 4.63.
I've mocked up this slope with some canes and it doesn't look too steep but...
an old post to this site refers to 1 in 10 as very steep
a local raod which is very steep is signed as 20%
(but obvioulsly I can still drive up it )
My aim is to keep as much of the garden as possible level but I don't want to end up with realy difficult access. Any thoughts on my preposed gradient would be appreciated.
Also, I'm thinking of concrete with a brushed surface rather than tarmac on the grounds of grip and cost. Am I thinking correct?
1:10 is steep for pedestrians and is considered too steep for disabled persons - the regulation is a maximum gradient of 1:12 for not more than 5 metres. However, for vehicles, 1:5 is not too much of a problem - local cars are coping on that 20% gradient, which is the same as 1:5.
You need to be careful that you don't create a grounding spot where the gradient meets the flat. Use a gradual transition to ensure no point is more than 150mm higher than a 2.4m straightedge.
Tarmac on a gradient such as this is never a good idea. It's difficult to lay (laying it is not too bad: it's the compacting that is a nightmare) and it tends to scuff too easily. Concrete, either cast in situ or as concrete block paving/flags is a much better option.
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