UK Standard

SHW Clause 803 / 805 — MOT Type 1 & Type 3 Sub-Base

Specification for Highway Works (SHW) — Series 800, Clauses 803 & 805

In short: MOT Type 1 (SHW Clause 803) and MOT Type 3 (SHW Clause 805) are the granular sub-base materials specified in the UK's Specification for Highway Works — Type 1 compacts to a dense load-bearing base, Type 3 has reduced fines to drain freely.

What SHW Clause 803 / 805 covers

The SHW (part of the Manual of Contract Documents for Highway Works) is the UK national standard for road construction; using SHW-compliant sub-base means your project meets the same engineering specification as public highways.

Clause 803 (Type 1) is the default dense, largely impermeable base for driveways and patios; Clause 805 (Type 3) is the free-draining choice for SuDS-compliant permeable paving.

Recycled grades 6F1/6F2/6F4/6F5 are SHW capping and fill materials; graded crushed concrete (6F2/6F5) can substitute for Type 1 on many domestic jobs.

SHW sub-base materials
Material Clause Drainage Best for
MOT Type 1 803 Low (dense) Driveways, patios — the default
MOT Type 3 805 High (free-draining) Permeable / SuDS paving
6F2 / 6F5 (recycled) 6F series Variable Budget sub-base / fill

Apply this standard

Calculators that use SHW Clause 803 / 805

Sub-Base (MOT Type 1)
Hardcore tonnes with 20% wacker-plate compaction factor built in.
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Paving Slab Calculator
Slab count for any patio area, factoring in joint gaps and wastage.
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Block Paving Calculator
Block-paving count and bags of kiln-dried jointing sand for any area.
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Patio Material Estimator
Full shopping list: MOT Type 1, sharp-sand bed and slab count for any patio size.
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Driveway Project Estimator
MOT sub-base, sharp-sand bedding and block-paver count for driveways.
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Official source: Specification for Highway Works (MCHW). Figures on this page are a plain-English summary for estimating purposes — always refer to the published standard for compliance.