How to Calculate the Gradient of Your Driveway

Are you lucky enough to have a driveway outside of your property? If you do, is it a sloped or level driveway? That’s actually a bit of a trick question, as in most cases there should be no such thing as a level driveway. Even if your driveway looks completely level, the likelihood is that it will have been built on a gradient to ensure rainwater can run off into the drains. A completely level and flat driveway will often collect rainwater, causing drainage problems that may even run into your home. In this article we will show you how to calculate the gradient of your driveway, so you know just how sloped it is and should be.

The Difference Between Flat and Level Driveway

Flat and level may mean the same thing to you in everyday, general language use. However, there is an important difference in the surfacing world. A driveway can be level but not flat and the same vice versa. In some circumstances, there may even be more than one gradient to deal with and work around. A level driveway is one that is close to being horizontal; whereas a flat tarmac driveway means the surface shows no undulations. So it is possible to have a flat driveway on a server slope.

Calculating the Gradient

The typical gradient required for good drainage is between 1:60 and 1:80. What this ratio means is over the length of a driveway, the end that features drainage channels should be one unit lower for every 60/80 units of length. So for example, if a driveway is 8 metres long, the drainage end should be 10cm lower than the opposite end (using the 1:80 ratios). The one major factor that affects the choice of ratio is the choice of material. Concrete and Tarmac surfaces need steeper 1:60 blocks, whereas paving can typically get away with a shallower angle.

Remember the Centre

It’s also important to consider the central area of your driveway, which in most cases should be higher than all of the edges. This is also to make sure that rainwater runs off to the sides rather than collecting in the middle. The same ratios as mentioned before should be used to calculate the gradient either side of the central area. If any part of your drive meets a house wall, the top surface must be at least 6 inches (15cm) below the damp-proof course. If your driveway has multiple angles, is curved or features various junctions, then calculating your different gradients can be quite challenging. If you find yourself in this position, choose one fixed starting point and measure out from there; it should all fall into place naturally.

Permeable Paving

If you are currently thinking of converting your front garden into a driveway, you must adhere to the latest government rulings regarding paving materials. Nowadays, it is very difficult to use anything other than permeable paving materials on your driveway – which isn’t a bad thing at all! These come with their own drainage qualities which means that gradients and not so important for permeable paving systems. Often, these systems are purposefully laid flat to encourage water retention, so that more water returns to the water table rather than running exclusively into the drains. For more advice on your possible draining solutions or for help with your driveway aspirations, give our team a call today on 01952 840 838.