In this blog, we will tell you whether or not gravel can be laid on top of tarmac and the answer to this question. Asphalt is a type of material that combines with other materials in order to form a mixture which gets laid down on roads as the final layer of a road surface. The final outer layer can have more than one mix of materials underneath such as gravel or sand which are used to give the surface a rougher appearance.
Unfortunately, the answer is that you should really take the tarmac up first if you want to replace it with a gravel driveway. Gravel, being a ‘soft’ driveway medium, needs a soft bedding.
Health and Safety
The problem with laying gravel on any hard surface, such as Tarmac or Concrete, is that it will roll around. This is unsafe and also means that you’ll lose the gravel quite quickly. As cars drive over it the gravel will be squeezed out to the sides and into whatever borders the driveway.
Obviously, we’re not sure of the exact situation with your driveway, but if you are able to build border walls about 3-4in (8-10cm) high that retain the gravel, then it might stay in place. But car tyres would probably dig furrows quite quickly, so you’d have to regularly rake the gravel back in place.
You would also have to put down three or four times the amount of gravel than you would normally, so it would cost a lot more than an ordinary gravel drive. It would still have the potential to be unsafe for people walking on it too, so we must advise strongly against this course of action.
Another problem with laying gravel on top of a harder surface is that you’re likely to get a poor finish. The gravel will get knocked by cars as they drive over it, leaving the stones underneath loose and careless. This can affect how your car drives if there are potholes in the driveway where stones have been forced into low points in the surface.
Taking up the tarmac drive shouldn’t be that big a deal anyway. Unless you have a very long drive all you need to do is spend a Saturday with a strong pick, a shovel and a skip. Break the top layer up, being careful not to go down more than a few inches and, assuming the tarmac had proper foundations, you should be left with a reasonably good surface to lay gravel on.
Don’t try to smooth the revealed foundation too much, as any undulations will help to keep the gravel in place. Depending on the surface that you reveal, you many even want to put down a layer of sharp sand to give something for the gravel to bed into.
Pick the Right Gravel
Of course, there are many different types of gravel. If you want to go for something that’s a bit sharper, this will help the gravel bind together. Smooth, small, round stones can be a bit too keen to roll away to where they aren’t wanted.
Gravel that’s less ‘finished’ also has the benefit of generally being cheaper than smooth, round products. But if you go too far down that road you can end up with gravel that is painful to walk on. The best advice is try to get to see a lot of samples before you decide what to buy.
In conclusion , it is possible to lay gravel onto tarmac provided you build a retaining wall with inwards joint on each side of the drive. With this method would be suited towards short, private drives providing access to your house and garden. However, we do not recommend this as the long term outcome will not be satisfactory and therefore we cannot endorse it. The best course of action would be to remove the existing tarmac and lay a new surface. We hope this blog has provided you with the answer to your question.