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Laying Concrete on Your Drive or Patio

By: Chris Hogan MSc - Updated: 10 Oct 2016 | comments*Discuss
 
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Laying a concrete driveway is a job that householders often take on as a DIY task, and there's no reason why you shouldn't achieve a good, long-lasting job, as long as you take care in the preparation and the laying. Unless you have a very long drive, it's likely that you'll have to mix the concrete yourself from raw materials, so the first job is to buy, hire or borrow a cement mixer.

Prepare the Tools and Site

Once you know when your mixer's going to be available you can prepare the ground. Do this by removing whatever is on the top layer of the site. Whether it's an old drive, grass or just dirt, you'll need to go down about 10cm. If the ground is very poor, you might need to go down another 10cm then fill that up with crushed and levelled hardcore (see our article Excavating For A Driveway on this site).

Make sure there are no weeds left and treat the site with a general purpose weedkiller if there are any doubts. Then set up boundaries to keep the concrete in the right place when it's poured on. This can be existing walls, decorative stone blocks or bricks, or temporary wooden barriers that will be removed once the concrete has set properly (see our article Formwork For Concrete Drives on this site). Any temporary barriers, known as shuttering or formwork, will need to be treated with release agent so that they can be removed afterward without damaging the concrete.

Get the Concrete Down

Lay down a damp-proof membrane which will stop the wet concrete from drying out too quickly, and also protect it from any chemicals (such as chlorides) in the base or sub-base, which might attack the underside of the concrete. Once that's down it's time to mix up the concrete according to the manufacturer's instructions. It can be levelled off initially with a spade or strong rake before being tamped down.

Tamping involves taking a timber with a straight edge and using it to tap down on the surface of the drive across its width, working from one end to the other. This spreads the concrete evenly along the drive and levels it, but also brings trapped air to the surface and makes sure the concrete is firmly bedded down onto the aggregate in the sub-base.

Finishing with Care

Concrete is often finished with mechanical smoothing machines once it's begun to cure, but for a domestic drive you're unlikely to want to go to the trouble. Apart from anything else, a smooth surface can be treacherous in the winter, so it's probably best left well tamped and then finished with a course brush, stoking parallel to the driveway. The resulting grooves will help drainage and give grip when it's wet.

With a house driveway it's not really necessary to worry too much about the drying out and curing processes. If it's likely to be a cold night, then sacking, straw or old carpet can be used to cover the drive overnight. It ought to be checked after 10-12 hours so that any minor flaws can be touched up or smoothed over before it hardens completely.

When to Use Your Driveway

After 24 hours you can take the shuttering away from the edges. It can be left for up to three days if necessary, but any earlier and the edge won't form properly. Take care when you are removing it to avoid damaging the edge. Keep everyone and anything off the drive for the first couple of days, and cars should not be used on the drive for at least five days. After that, it's yours to use and admire.

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[Add a Comment]
I had a driveway laid recently but thought it a little odd that the tarmac wasn't raked flat before rollering. It was barrowed in long heaped channels and rollered. This has left some stripes in the tarmac and weak spots that are crumbling. Is this a normal way of rollering tarmac?
Milly - 10-Oct-16 @ 10:13 AM
When you lay a tarmac path should it be flat or domed when it is finished? What height difference should you have from one side of the path to the other, to allow rain water run off away from the building?
Taffy - 25-Feb-16 @ 3:15 PM
Nitram - Your Question:
My garage was extended forward years ago, resulting in a portion of the old Tarmac drive being inside the garage. Over the years this has deteriorated. I would like to lay concrete to match the existing base. Having dug up some Tarmac I see that it goes down 5cm before I hit hardcore.Talking to ready mix concrete companies they recommend a minimum of 10cm of concrete so I'd have to dig the hardcore out, which is something I'd rather not do.Is there something I could lay over the Tarmac or failing that just dig out to a depth of 5cm and fill from there? Note the garage will only be used for pedestrian traffic - no cars.

Our Response:
If you're not planning on using it for vehicles and it will not be exposed to the elements (being indoors), a depth of 5cm should be sufficient.
DrivewayExpert - 26-Aug-15 @ 11:35 AM
My garage was extended forward years ago, resulting in a portion of the old Tarmac drive being inside the garage. Over the years this has deteriorated. I would like to lay concrete to match the existing base. Having dug up some Tarmac I see that it goes down 5cm before I hithardcore. Talking to ready mix concrete companies they recommend a minimum of 10cm of concrete so I'd have to dig the hardcore out, which is something I'd rather not do. Is there something I could lay over the Tarmac or failing that just dig out to a depth of 5cm and fill from there?Note the garage will only be used for pedestrian traffic - no cars.
Nitram - 24-Aug-15 @ 10:14 AM
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