Asphalt Thickness Guide: How Thick Should Asphalt Be?
Asphalt thickness in Pakistan follows NHA General Specifications. This guide gives standard thicknesses for driveways, parking lots and highways.
Residential Driveways (Pakistan)
- Light vehicles: 40 mm Class B over 100 mm aggregate base.
- Heavier vehicles: 50 mm Class A over 150 mm aggregate.
Commercial Parking
- Standard: 50 mm wearing + 75 mm base = 125 mm on 200 mm sub-base.
- Heavy-duty (containers, trucks): 50 mm wearing + 100 mm base on 300 mm aggregate.
Roads (NHA-Aligned)
- Provincial roads: 50 mm wearing + 75 mm base.
- National highways: 50 mm wearing + 100 mm base + sub-base.
- Motorways: Multi-lift design, 200–300 mm asphalt total.
Overlays
Overlays are placed on an existing sound surface to extend life:
- Driveway overlay: 1.5–2 in (40–50 mm).
- Parking lot overlay: 1.5–2 in after milling 1 in.
Climate Considerations
In freeze-thaw climates, add 0.5–1 in to baseline figures and consider a deeper base course. In hot climates, focus on binder grade rather than extra thickness.
The Base Course Matters More Than You Think
Cutting the asphalt depth by 0.5 in saves perhaps 5% on material. Cutting the aggregate base often shortens pavement life by years. If budget is tight, never economize on the base.