Tarmac Calculator
Calculate asphalt and tarmac requirements for your paving project with precision
Calculate Your Tarmac Requirements
What These Results Mean
Tarmac Thickness Guidelines
Proper tarmac thickness is crucial for longevity and performance. The required depth varies based on the application and expected load.
| Application | Minimum Thickness | Recommended Thickness | Sub-base Required |
|---|---|---|---|
| Residential Driveway | 50mm | 70-100mm | 150mm Type 1 |
| Car Park (Light Traffic) | 75mm | 100-125mm | 200mm Type 1 |
| Road Surface | 100mm | 150-200mm | 300mm+ Type 1 |
| Heavy Duty Industrial | 150mm | 200-250mm | 400mm+ Type 1 |
| Footpath/Cycle Path | 30mm | 40-50mm | 100mm Type 1 |
How to Calculate Tarmac Requirements
Basic Calculation Method
Calculating tarmac requirements involves three key measurements and a standard density conversion:
- Area Calculation: Length × Width = Area in square metres (m²)
- Volume Calculation: Area × Depth (in metres) = Volume in cubic metres (m³)
- Weight Conversion: Volume × 2.4 = Weight in tonnes
Standard Asphalt Density
Hot mix asphalt typically has a density of 2.4 tonnes per cubic metre (2,400 kg/m³). This density can vary slightly depending on the aggregate type and mix design, but 2.4 is the industry standard for calculations.
Waste Factor Considerations
Always add 5-10% extra material to account for:
- Compaction losses during installation
- Minor spillage and wastage
- Irregular surface variations
- Edge trimming requirements
Types of Tarmac Applications
Residential Driveways
For domestic driveways, a two-layer system is typically used:
- Binder Course: 50-60mm of coarse asphalt for structural strength
- Surface Course: 20-30mm of fine asphalt for smooth finish
Commercial Car Parks
Car parks require greater thickness to handle repeated loading:
- Base layer: 75-100mm depending on traffic volume
- Enhanced sub-base preparation essential
- Proper drainage considerations
Road Surfaces
Public roads need robust construction for heavy vehicle loads:
- Multiple layer construction with base, binder and surface courses
- Total thickness typically 150-250mm
- Specialist mix designs for different traffic categories
Frequently Asked Questions
How accurate is this tarmac calculator?
This calculator provides estimates accurate to within 5% when proper measurements are entered. It uses industry-standard density values of 2.4 tonnes per cubic metre and includes standard waste factors. For critical projects, always consult with your supplier for final quantities.
What’s the difference between tarmac and asphalt?
Tarmac historically used tar as a binder, whilst modern asphalt uses bitumen. Today, the terms are often used interchangeably as most surfaces use bitumen-based asphalt. Both provide durable, weather-resistant paving solutions.
How much does tarmac cost per tonne in the UK?
Tarmac costs typically range from £45-80 per tonne depending on location, quantity, and specification. Hot mix asphalt for driveways averages £55-65 per tonne delivered. Specialist mixes or coloured asphalt cost more.
Do I need planning permission for a tarmac driveway?
Most residential driveways under 5 square metres don’t require planning permission. Larger driveways need either permeable surfacing or proper drainage to soakaways. Check with your local planning authority for specific requirements.
How long does tarmac take to cure?
Tarmac can typically support foot traffic within 2-4 hours and light vehicle traffic within 24 hours. Full curing takes 6-12 months, during which the surface continues to harden and improve.
Can tarmac be laid in winter?
Tarmac can be laid in temperatures above 5°C, but optimal conditions are above 10°C with dry weather. Cold weather slows curing and may affect compaction quality. Professional contractors adjust mix temperatures accordingly.
Sub-base Preparation
Importance of Proper Sub-base
The sub-base provides the foundation for your tarmac surface. Poor preparation leads to cracking, settlement, and premature failure.
Sub-base Materials
- Type 1 Aggregate: Primary crushed stone, well-graded for excellent compaction
- MOT Type 1: Ministry of Transport specification aggregate
- Recycled Concrete: Environmentally friendly alternative for some applications
Installation Process
- Excavate to required depth plus sub-base thickness
- Install geotextile membrane if ground conditions are poor
- Lay sub-base material in lifts of 75mm maximum
- Compact each lift with appropriate machinery
- Check levels and falls for drainage