Yes – in most cases, you do need to consider drainage when installing a tarmac driveway. Since tarmac is not a permeable surface, water needs to be directed somewhere safe. Without proper drainage, you could face pooling, surface damage, or even fall foul of planning regulations.
Let’s take a closer look at when drainage is required, what your options are, and what happens if you ignore it.
Why Drainage Is Important
Tarmac is a solid, water-resistant surface. That’s great for durability – but it also means water can’t soak through it. If rainwater has nowhere to go, it can:
- Pool in low spots
- Weaken the surface over time
- Cause frost damage in winter
- Overflow into public drains or neighbouring properties
More importantly, UK planning regulations require proper drainage for driveways over 5 square metres if they use impermeable materials like tarmac.
Legal Requirements
Since 2008, planning rules in England state that you do not need planning permission if:
- The driveway uses a permeable surface (like gravel or permeable tarmac), or
- Rainwater drains into a lawn, flowerbed, soakaway, or other permeable area on your property
But if water runs off onto the public road or footpath, or into the mains drainage system without permission, you may need to apply for planning consent – or be required to retrofit drainage later.
There are several ways to manage drainage effectively without needing planning permission:
- Channel drains – Installed across the front of the driveway to catch water and direct it to a soakaway
- Soakaways – Underground pits filled with gravel or crates that absorb water slowly into the ground
- Permeable borders – Grass or gravel strips along the edge to help absorb runoff
- Driveway slope – The simplest option, if possible, is to gently slope the driveway so water flows onto your own garden or lawn
All of these options help keep surface water off public drains and prevent water damage to the driveway itself.
What Happens If You Skip Drainage?
Ignoring drainage might save a bit of money upfront – but it usually comes back to bite.
- Standing water can seep into small cracks and freeze in winter, breaking up the surface
- You could be forced to redo the work if it breaches planning rules
- Your driveway might become slippery or even unusable in heavy rain
Proper drainage isn’t just a legal box-tick – it’s key to making sure your driveway lasts.
Final Thoughts
Yes – drainage is essential for most tarmac driveways. Whether you’re installing a brand new surface or replacing an old one, it’s worth spending the time and money to get water management right.
The good news is that most reputable contractors will include drainage solutions as part of the quote – and advise on what’s required based on the slope, ground type, and location.