MOT Type 2 – What Is It?
Free-draining clean stone sub-base for permeable applications
MOT Type 2 Sub-Base Material
What It's Used For
MOT Type 2 is specifically designed for applications requiring drainage while maintaining structural support.
- Drainage layers beneath structures
- French drain construction
- Soakaway surrounds
- Permeable paving sub-base
- Trench backfill where drainage needed
- Behind retaining walls
Material Composition
Clean graded crushed stone with minimal fines, allowing water to pass through freely while maintaining stability.
- 40mm to 4mm graded stone
- Maximum 5% fines content
- Angular crushed aggregate
- High void ratio for drainage
- Typically limestone or granite
Key Differences from Type 1
Understanding when to use Type 2 instead of Type 1 is critical for project success.
- No binding fines - remains permeable
- Won't compact to solid mass
- Better drainage characteristics
- Less stable than Type 1 when compacted
- Not suitable for direct trafficking
Load Sizes Available
Flexible delivery options to match your drainage project requirements.
- 20-tonne loads (standard)
- 10-tonne loads (smaller projects)
- Grab lorry delivery available
- Bulk bags for restricted access
Technical Specifications
| Property | Specification |
|---|---|
| Standard | Department of Transport Type 2 |
| Size Range | 40mm to 4mm nominal |
| Grading | Single-sized aggregate, minimal fines |
| Fines Content | Maximum 5% passing 4mm sieve |
| Permeability | High - free draining material |
| Void Ratio | Approximately 30-35% when compacted |
| Documentation | Grading certificates and source documentation provided |
Frequently Asked Questions
When should I use Type 2 instead of Type 1?
Use Type 2 when drainage is the priority. It's ideal for French drains, soakaways, behind retaining walls, or under permeable paving. Type 1 is better for load-bearing applications like driveways and roads where you need a solid, compacted base.
Can MOT Type 2 be used under driveways?
Not directly. Type 2 can be used as a drainage layer beneath Type 1, but shouldn't be the only sub-base under trafficked areas. Without fines to bind it, Type 2 remains loose and can cause rutting under vehicle loads.
How much Type 2 do I need for drainage?
For French drains, typically 150-300mm depth around perforated pipes. For soakaways, surround crates with minimum 150mm on all sides. Coverage: approximately 2 tonnes per 10m² at 100mm depth.
Does Type 2 need compacting?
Light compaction only - just enough to stabilise but not close the voids. Over-compaction defeats the purpose by reducing drainage capacity. Use a vibrating plate on low frequency or hand tamp.
Can I mix Type 1 and Type 2?
No - mixing defeats the purpose of both materials. Type 2's drainage properties are lost when fines are added, and Type 1's binding properties are compromised when diluted with clean stone.
What's the drainage rate of Type 2?
Properly laid Type 2 has a permeability rate of approximately 1-10 metres per day, depending on compaction. This makes it ideal for SuDS (Sustainable Drainage Systems) applications where water needs to infiltrate quickly.
Need MOT Type 2 for Drainage?
Free-draining aggregate delivered across London with grading certificates.
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