How Is a Tarmac Driveway Laid? The Process, Layer by Layer

Tarmac driveways are built from the ground up in layers: dig out to around 175-200mm below the finished level, lay and compact a crushed stone sub-base, set the edging, then lay a hot binder course and a hot surface course, each rolled while still hot. Most of what decides whether a drive lasts 15 to 20 years or cracks within two happens before any tarmac arrives. Here is the process step by step, as it should be done on a domestic drive.

Before anyone digs: levels, falls and drainage

The first job is on paper and with a level. The finished surface has to sit below the house damp-proof course; building regulations guidance (Approved Document C) puts the damp-proof course at least 150mm above adjoining ground. It also has to fall away from the house so water runs off. Pavingexpert recommends a minimum fall of 1:80 for tarmac, with 1:40-1:60 preferred.

Then drainage. Standard tarmac is impermeable, and in England a new or replacement front drive over 5m² that is not permeable needs to drain onto your own land (a lawn, border or soakaway) or it needs planning permission. That usually means a channel drain at the low point, a soakaway, or falls towards a border. It has to be designed before excavation, because it sets the levels for everything else.

Step 1: break out and excavate

The old surface comes out, along with topsoil, roots and any soft material. Pavingexpert's typical specification digs to at least 200mm below finished level; on its construction page the dig is roughly surface course plus binder course plus sub-base, around 175mm minimum on typical residential work. Soft spots are dug out deeper and backfilled with compacted stone.

Roots and buried rubbish are where drives fail later. On one of our tarmac driveways in Finchfield, the job involved removing five large tree roots and fitting a new drainage system where there had been none.

Step 2: membrane where needed

A geotextile membrane over the formation is not always needed. Pavingexpert suggests one where deep-rooted, pernicious weeds are a problem or where there is doubt about the ground underneath. It separates the sub-base from the soil so the two do not mix.

Step 3: sub-base

The sub-base is the real structure of the drive. It is crushed stone, usually MOT Type 1, laid in layers and compacted with a plate compactor or roller until it is tight and level. Pavingexpert's typical domestic specification calls for a minimum of 100mm; many installers lay more on soft or clay ground. The Finchfield drive above took 16 tonnes of Type 1.

The sub-base is shaped to the same falls as the finished surface, so the tarmac layers on top are an even thickness everywhere. The depths of each layer are set out in how thick tarmac should be on a driveway.

Step 4: edging and drainage

Free edges need restraint. Pavingexpert says edgings or kerbs must be used on free edges, because unrestrained tarmac crumbles. Kerbs, blocks or setts are laid on a concrete bed and haunched behind, so they are solid before the tarmac is laid against them. Channel drains, gullies and any ducts for lighting or EV cables go in now too.

Step 5: binder course

The binder course is the load-bearing asphalt layer, typically around 50mm of dense mix with 20mm stone. It arrives hot from the plant, is spread by hand or machine to an even depth, and is rolled while hot. Pavingexpert recommends at least 40mm and preferably 50mm. If the surface course is not laid within a week, the binder course should be sealed with a sealing grit, and before the surface course goes on it gets a bond coat so the layers stick together.

Step 6: surface course

The surface course is the finish: typically 20-30mm of a fine dense mix, usually 6mm stone on a drive. It is spread over the binder course, raked to level around kerbs, covers and thresholds, and rolled straight away. Pavingexpert allows a deviation of no more than 6mm from the correct level on the surface. Joints with existing surfaces are cut square and sealed.

Step 7: rolling and finishing

Compaction is what turns loose hot material into a dense, durable layer. Domestic drives are usually rolled with a twin-drum vibrating roller, with plate compactors or hand rollers in tight corners. Timing matters: rolled too late, the material has cooled and will not compact; rolled too soon, it shoves and marks. The British Standard BS 594987 covers the transport, laying and compaction of asphalt.

You can usually walk on a new drive after a few hours, but keep cars off for several days and avoid turning wheels on the spot for the first weeks.

Why hot tarmac is not a DIY job

Hot tarmac has a short working window between the lorry and the roller. A crew has to spread, rake and roll a full load before it cools, keep the thickness even, and work the joints, all with heavy kit. Get it wrong and you have a drive with cold joints, thin patches and roller marks that cannot be fixed without digging it out. The groundwork is also heavy: tonnes of spoil out, tonnes of stone in. For small repairs, cold lay is the homeowner's product; a new drive is a crew's job.

Paths and smaller areas

Paths and patios follow the same principles, with a lighter build where only feet will use them, and tarmac paths need just as much attention to edging and falls as the drive.

How we lay tarmac drives

We dig new drives out rather than laying over old ground, build a compacted base, and lay hot tarmac with our own team, from breaking out the old surface to the final roll. That is what our tarmac drives are built on, and it is why they carry a 10-year guarantee. If you want the same process on a pattern imprinted surface, our pattern imprinted concrete driveways start with the same groundwork.

Our tarmac work around Wolverhampton goes back over 25 years. Book a free site visit and we will walk you through the plan for your drive.