4/20 mm pipe bedding for larger diameter runs
4/20 mm graded bedding is the workhorse size for larger-diameter and deeper drainage. The wider grading gives strong interlock and good haunch support under 225 mm and above, and it places quickly in volume — which matters when a trench run is measured in hundreds of metres rather than tens.
Key specifications
- Nominal size
- 4/20 mm graded
- Typical use class
- Bedding, haunch and surround
- Material
- Primary crushed rock or gravel
- Compaction
- Strong interlock, good haunch support
- Supply formats
- Loose tipper, grab lorry, artic, bulk bag
- Typical load
- 16–20 t tipper, 28–29 t artic
Typical uses
- Bedding and surround to 225 mm and larger drainage
- Deep trench work where haunch support is critical
- High-volume adopted sewer and highway drainage runs
- Attenuation and soakaway fill where void ratio matters
Lead time and delivery
Stocked line — most postcodes in England and Wales are dispatched within 24–72 hours of order confirmation. Scotland and Highland deliveries are typically 3–5 working days. Programmed civils schedules are booked in advance and delivered to your call-off dates.
Tipper, grab and artic haulage. Where we are also removing surplus from your site the same lorry returns loaded, cutting haulage cost and empty running.
Frequently asked questions
Is 4/20 mm suitable for adopted sewers?
It is widely used for adopted drainage bedding and surround, but the size and class must match the adopting authority's detail and your engineer's specification. We can supply grading and test data to support submission.
Can you deliver 4/20 mm in artic loads?
Yes — for bulk civils programmes we deliver 28–29 tonne artic loads direct to site on a booked call-off schedule, which is the lowest cost per tonne where access allows.
Other bedding and capping sizes
Related pages
Everything you need to spec, price and move material — tools, services and the exact material pages they relate to.
- Aggregate calculatorWork out tonnes and tipper loads from area and depth before you order.
- Aggregates, sub-base & cappingMOT Type 1, 6F2 and 6F5, ballast, sands and single-size bedding stone.
- Tipper & artic hireRigid and artic bulk haulage for aggregate in and muck out on one movement.
- Recycled aggregatesRecycled Type 1 and pipe bedding where the spec allows a secondary material.
- Instant RFQ builderList materials, quantities, postcode and date in one consolidated request.
- Areas we coverCity-by-city delivery and haulage coverage across England, Scotland and Wales.