Sub-base & capping

6F5 capping to SHW Clause 613

6F5 is a coarse graded capping material to Specification for Highway Works Clause 613, used to build a working platform over weak subgrades before the sub-base goes down. On soft ground it is far more economical than importing extra Type 1, and it spreads and compacts into a stable layer that protects the formation through the wet.

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Key specifications

Grading: Coarse graded, nominal 0–125 mm
Specification: SHW Clause 613 capping (Class 6F5)
Material: Primary crushed rock
Typical layer thickness: Commonly 300–600 mm, per design
Supply formats: Loose tipper, artic bulk loads
Typical load: 16–20 t tipper, 28–29 t artic

Typical uses

Capping layer over weak or CBR-deficient subgrades
Temporary haul roads and site working platforms
Highways and adopted road construction to SHW spec
Bulk fill and level-up on earthworks schemes

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

What is the difference between 6F5 and 6F2 capping?

Both are capping materials under SHW Clause 613. 6F5 is typically a coarser graded fill used where a thicker, robust platform is needed; 6F2 is the finer of the two gradings and is widely used as general capping fill. Follow your earthworks specification for which class is required.

How thick should a 6F5 capping layer be?

Thickness is a design decision based on subgrade CBR and the loading above — commonly 300–600 mm. Your geotechnical engineer should specify it; we supply the tonnage against the design.

Other bedding and capping sizes

Pipe Bedding 4/10 mm Pipe Bedding 10 mm Pipe Bedding 4/14 mm Pipe Bedding 14 mm Pipe Bedding 4/20 mm Pipe Bedding 20 mm All aggregates

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