How to build a tarmac driveway
Comstock Images/Comstock/Getty Images
A tarmac driveway can have a service life of 30 years or more if it is built correctly. Tarmac driveways can also be called tarmacadam, asphalt, bitumen or blacktop driveways and are generally cheaper than concrete or paving.
It is recommended you have a contractor in to actually lay the tarmac because the working window is very short, and once hot tarmac cools down it is no longer workable. To reduce costs, you can pool with neighbours who also want to have their driveway done, as the major costs are in getting the heavy machinery to your site.
Plan exactly where you want your driveway to go and mark it out using either small marker stakes or spray paint on the ground. Excavate it to a depth of 160 to 180 mm below the level you want the finished driveway to be. Use a shovel and wheelbarrow if you want to save money or get a Bobcat in if you want to save time.
Retain the edges of the driveway. If an edge abuts a garden wall, that is an ideal situation, but otherwise use edging kerbstones, stone, concrete blocks or timber, although timber will not last as long. Lay them in concrete with at least 75 mm below the base and so the top is at the desired driveway level. Check everything is aligned properly and allow the concrete to set for at least 24 hours.
Spread gravel between your driveway edging to a depth of around 100 mm. This can be leveled out using a shovel and/or rake. Compact the gravel using a roller or vibrating plate compactor. The tarmac contractor will be using a roller so you could arrange for them to compact the sub-base just before they lay the binder course.
Lay the binder course; this is the first of the two tarmac layers and has larger size aggregates of about 20 mm. Lay this as quickly as possible as it is delivered hot, and roll it as soon as it is laid. Normally it takes six to eight passes of the roller to consolidate it well. The binder course is normally about 50 mm deep.
Lay the surface course: this has smaller size aggregates to give a finer looking and hard wearing top surface. This is laid in the same manner as the binder course and can be done immediately after it. Care must be taken with leveling the surface course so that the driveway is flat and comes to the required level. Allow 24 hours before driving on the new surface.
- Dip shovels and rakes in diesel when leveling hot tarmac. This prevents it sticking to the metal.
- The heavy machinery used to deliver, lay and roll tarmac can be noisy so it is best to give your neighbours advance warning.
- Do not seal a new tarmac driveway until it has at least 90 days to cure and harden, but preferably six to nine months. After that you can use a coal-tar based sealer every three to five years to keep it looking good.
- Comstock Images/Comstock/Getty Images