Tarmacing Your Driveway
Installing a tarmac driveway properly can mean the difference between a driveway that will last few years and a driveway that can last up to 20 or even 30 years.
We only get one chance to get the job done properly. Whether you’re removing and replacing an existing tarmac driveway, or having a brand new one installed, the process is pretty much identical.
Doing it properly!
There are tarmac driveways that look just as good as they have for a decade and driveways that last no more than a year or a few months. Don’t fall into the trap of countless home-owners who have lost several thousands of dollars because of a botched driveway project.
This means avoiding inexperienced or fly-by-night contractors. Here’s how to install a tarmac driveway the right way.
First is the preparation of the sub-grade. Proper sub-grade preparation is extremely important for a driveway that will last a lifetime. In short, the better the sub-grade preparation, the better the driveway.
Drainage planning is the most crucial part of all. Excavating and fine-grading the soil is the first step in proper water drainage. We want to ensure the following two things:
The water runs away from the garage or house to avoid flooding.
The water runs off of the tarmac itself. This is because we want to avoid water pooling and sitting on the surface of the tarmac to avoid pavement failures and premature degradation.
You’ll also need to ensure that the surface on which you’re installing the tarmac is stable. This requires moving the following types of material from the earth:
Rocks and gravel
Material like rocks or gravel should be removed prior to grading and paving the driveway. A good rule of thumb is that anything that moves beneath our feet should not be paved on and should be removed from the driveway prior to installing the tarmac.
Any soft and unstable material
If the planned driveway area consists of any unstable material like clay, sand, or topsoil, this should also be removed and a strong base material like road base, recycled concrete, or limestone just to name a few options, should be laid down prior to installing the new hot tarmac.
This stabilises the sub-grade and will result in a stronger, more durable driveway.
A note on long driveways
When it comes to long driveways, contrary to popular belief, they should not be graded with a crown in them. Long driveways should be graded flat, but with a slight pitch to either side to get the water to run off of the surface of the tarmac.
Driveways with crowns have absolutely no advantage over others. As a matter of fact, crowning can actually cause premature deterioration and pavement failure. Crowning long driveways is also a very common way for tarmac contractors to rip home-owners off.
So avoid crowns at all costs!
Once the grading is complete, the sub-grade should then be compacted with the rollers before installing the tarmac.
Next, a herbicide should be put down to minimize vegetation growth. Weeds growing up through the tarmac can cause irreparable damage and eventually pavement failure.
Laying the Tarmac
Now we’re ready to go about laying the tarmac. The tarmac should be installed using a tarmac paving machine and not by hand. This will provide a consistent average depth of tarmac throughout the driveway and a much smoother finish to the surface.
Some areas that are too small for the equipment to get to will need to be installed by hand which can slightly raise the overall cost.
Experienced tarmac-rakers are also an integral part of a nicely finished surface.
When the tarmac is being laid from the paving machine, it’s not compacted yet. Therefore it needs to be compacted. An experienced contractor is incredibly crucial for this step. The tarmac should be compacted soon after it’s laid out of the paving machine while it’s still hot.
Should excessive cooling occur before rolling, it’s not going to get compacted well enough.
Conversely, too little compaction will cause water to penetrate the tarmac and that’ll cause it to deteriorate much faster, cutting the life-expectancy dramatically.
On the other hand, too much compaction while it’s still hot can cause the tarmac to stretch and crack causing premature pavement failure.
The most important aspect of laying tarmac is undoubtedly the thickness. The thickness is going to determine whether it lasts only a few months or 20 to 30 years as it should.
Installing in 2 Lifts
Some contractors may also offer to install a driveway in two lifts. What this means is, they’ll install one layer of tarmac, compact it, then start at the beginning of the driveway again, and install a second layer of tarmac, then compact that layer.
This is not an essential requirement and is often overkill for a driveway, but it has the advantage of providing a more durable driveway, a much smoother ride, and a much more beautifully finished surface.
It does also cost more money since there are more time, labour, and materials required. So be ready to pay additional costs if you opt for a driveway that’s installed in 2 lifts.
Compacting the Edges
Edges are greatly strengthened through compaction and this also makes them less prone to cracking and deterioration.
During the grading process, some of the sub-grade material should have been left along the edges so that once the driveway is complete, that material can be pulled up to the edge of the asphalt.
This gives the driveway the appearance of sitting down in the soil, rather than just being laid out on top, leaving the edges exposed. This will also help create a nice strong shoulder to transition from the asphalt, in turn helping to minimize cracking in the event that a vehicle drives off of the edge.
Guarding the Driveway against Traffic
At this point, the project is completed. All that remains is to set up danger tape and cones to prevent vehicles from driving over the surface while it’s cooling down.