Asphalt Driveway glossary of terms & specifications
14 technical terms, material grades and Irish standards explained in plain English so you know exactly what is on a written quote.
Sorted A to Z for quick reference when comparing specifications.
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Key asphalt driveway terms explained
ACO Linear Channel Drain
A grated polymer-concrete drainage channel set in concrete across the road threshold or garage door to intercept surface rainwater run-off and connect it to a soakaway or storm drain.
Binder Course (60mm Base Course)
A coarse 14mm or 20mm hot-mix macadam structural layer compacted to 50mm–60mm directly over the Clause 804 stone sub-base before the fine top wearing course is laid.
Bitumen Emulsion Tack Coat (K1-40)
A sticky cationic bitumen spray applied over a cleaned existing tarmac or concrete driveway so a new 30mm–40mm SMA overlay bonds monolithically without slipping.
Clause 804 Sub-Base
Crushed, graded quarry stone spread over a geotextile membrane and compacted in layers to 150mm–200mm with a vibrating roller to carry cars, SUVs and oil lorries without rutting.
Cold-Lay Repair Macadam
Bagged solvent-cut bitumen macadam used only for temporary pothole patching; never suitable for surfacing a full residential driveway, which requires hot-mix quarry asphalt laid at 130°C–160°C.
Dense Bitumen Macadam (DBM / Tarmac)
Traditional continuously graded tarmacadam; durable and cost-effective, though slightly more open-textured than modern Stone Mastic Asphalt (SMA) under tight power-steering turns.
Geotextile Separation Membrane
A heavy woven or non-woven fabric laid over soft clay subsoil before importing Clause 804 stone so soil cannot pump upwards into the sub-base over time.
Granite Sett Entrance Apron
Three to five rows of 100×100mm or 200×100mm silver or oatmeal granite cobbles haunched in concrete across the gateway to frame the blacktop and absorb heavy wheel impact at the road edge.
Hot-Rolled Asphalt (HRA)
A dense sand-and-bitumen matrix with coated stone chippings rolled into the surface, widely used on public roads and heavy traffic entrances.
Key-Cut Rebate Chase
A 35mm-deep groove saw-cut into existing tarmac at the road threshold and garage door so a new resurfacing overlay finishes completely flush rather than leaving a raised lip.
Penetration-Grade Bitumen
Refinery bitumen binder graded by hardness (typically 70/100 or 100/150 pen in Ireland) that binds heated stone aggregate together once compacted and cooled.
Soakaway Crate / Rubble Pit
An underground void filled with clean single-sized stone or modular geocellular crates wrapped in geotextile membrane that lets driveway rainwater percolate into the garden subsoil.
Stone Mastic Asphalt (SMA)
A premium gap-graded hot asphalt rich in bitumen and cellulose fibres with a tight stone-on-stone skeleton (6mm or 10mm) that resists power-steering scuffing, weeds and frost.
Tar and Chip (Surface Dressing)
Hot bitumen emulsion sprayed onto a prepared base and dressed with 10mm–14mm washed stone chippings, rolled in to give a traditional country-house gravel look on long rural avenues.
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Questions homeowners ask
How much does an asphalt driveway cost in Ireland?
Resurfacing a sound existing tarmac or concrete driveway with a 40mm SMA asphalt overlay costs €55 to €80 per m² (€2,800 to €4,200 for a typical 50 m² 2-car driveway). A full dig-out with a 150–200mm compacted Clause 804 stone sub-base, 60mm binder course and 40mm SMA surface course costs €75 to €115 per m² (€3,800 to €5,800 for 50 m², or €6,000 to €9,000 for an 80 m² 3–4 car driveway).
What is the difference between SMA asphalt and tarmacadam?
Traditional tarmacadam uses graded stone in a softer binder that can scuff when modern heavy cars or EVs turn their power steering on the spot. Stone Mastic Asphalt (SMA) uses a gap-graded stone skeleton bound with fibre-modified bitumen — the stones lock directly together, giving a denser, smoother, scuff-resistant surface that lasts 20 to 25 years.
Can you lay new asphalt over an existing concrete or tarmac driveway?
Yes, provided the existing slab or tarmac is structurally sound, does not rock or hold deep puddles, and the threshold height at your house damp-proof course (DPC) and road footpath allows an extra 40mm depth. An overlay costs €55 to €80 per m² after sweeping, joint-sealing and spraying a hot K1-40 bitumen tack coat.
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