10-20mm Shingle – What Is It?
Clean washed gravel for drainage, concrete and decorative uses
10-20mm Pea Shingle
What It's Used For
10-20mm shingle is versatile clean stone ideal for both functional drainage and decorative applications.
- French drain construction
- Soakaway systems
- Drainage behind retaining walls
- Concrete aggregate (with sand)
- Decorative pathways and drives
- Garden borders and features
- Pipe bedding and surround
- Permeable paving sub-base
Material Properties
Natural rounded river gravel or angular crushed stone, washed clean of fines.
- Single-sized aggregate 10-20mm
- No fines or sand content
- Typically Thames Valley gravel
- Rounded or angular available
- Natural colour variation
- 35-40% void ratio for drainage
- Non-frost susceptible
Drainage Applications
Why 10-20mm is the standard size for drainage systems.
- Optimal balance of flow and stability
- Won't wash away like smaller sizes
- Won't block pipes like larger sizes
- Self-compacting without closing voids
- Allows geotextile wrapping
- Prevents soil migration
Decorative Uses
Popular for landscaping due to its neat appearance and practical benefits.
- Driveway surface (with grid system)
- Garden pathways
- Mulch alternative around plants
- Japanese garden features
- Pond surrounds
- Available in bulk or bags
Technical Specifications
| Property | Specification |
|---|---|
| British Standard | BS EN 12620 (Aggregates for Concrete) |
| Size Designation | 10/20 (10mm to 20mm) |
| Grading Limits | 85-99% passing 20mm, 0-20% passing 10mm |
| Fines Content | Maximum 1% passing 0.063mm |
| Shape | Rounded (river) or Angular (crushed) |
| Bulk Density | Approximately 1.5 tonnes/m³ |
| Permeability | High - typically 5-50m/day |
Frequently Asked Questions
What's the difference between 10mm and 20mm shingle?
10mm shingle (actually 6-10mm) is smaller, better for decorative paths but can migrate. 20mm shingle (actually 10-20mm nominal) is the standard for drainage - large enough to stay put, small enough for good water flow. The 10-20mm size is most versatile for both drainage and decorative uses.
How much 10-20mm shingle for a French drain?
For a standard 300mm wide x 600mm deep trench with 100mm perforated pipe: approximately 0.15m³ per linear metre, or 225kg. Always surround pipe with minimum 50mm shingle on all sides. Add 10% for settlement.
Can I use 10-20mm shingle for concrete?
Yes, but you must add sharp sand. Mix ratio: 1 cement : 2 sharp sand : 3 shingle (1:2:3) for strong concrete. Without sand, concrete won't bind properly as the shingle alone has too many voids. For drainage concrete (pervious), use shingle only with less cement.
How deep for a shingle driveway?
Minimum 50mm depth on solid sub-base, ideally 75mm for regular car use. Must have solid edge restraints to prevent spread. Consider cellular grid systems to prevent rutting. Not suitable for heavy vehicles without reinforcement. Top up annually as it settles.
Rounded or angular shingle - which is better?
Rounded (river gravel) is better for decorative use - comfortable underfoot, doesn't compact. Angular (crushed) is better for drainage and sub-bases - interlocks better, more stable. Both work for French drains, but angular gives slightly better flow rates.
How much area does a tonne cover?
At 50mm depth, 1 tonne covers approximately 12-13m². At 75mm depth (recommended for driveways), 1 tonne covers 8-9m². For drainage trenches, calculate volume needed and multiply by 1.5 tonnes/m³.
Need 10-20mm Shingle?
Clean gravel for drainage and landscaping. Bulk loads or bags available.
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