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Lay a patio sub-base.
Excavate, compact MOT type-1 to 100-150mm — the foundation that decides whether a patio lasts 5 or 25 years.
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Costs, timelines, pitfalls and the right questions to ask before any groundworks starts on patio Sub-Base Construction.
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Inadequate sub-base depth
Cheap installs skimp. 100mm minimum, 150mm for heavy use.
Wrong material
Sand or gravel inadequate. Must be compactable aggregate (Type 1 MOT).
No compaction
Loose sub-base settles. Vibrate-compact 95%+ density.
Drainage falls wrong
Patio drains to house = damp. 1:80 minimum away from building.
Costs & timeline
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Indicative UK ranges and what affects price.
Cost range
By job type
Inc. VAT · 2026
Source: NMT quotes
Source: NMT quotes
Sub-base per m²Type 1 MOT 100-150mm
£15–£50/m²
Type 1 MOT per tonneMaterial only
£30–£80
Excavation per m²Plus disposal
£10–£30/m²
Sub-base for 30m² patioStandard install
£500–£1.5k
Geotextile membranePer m², optional
£3–£10/m²
Compaction (vibrating plate)Usually included
£1–£1
!
Quote spread is typically ± 18% — always get 3 quotes.
At a glance
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Quality patio sub-base prevents sinking and ensures durability. Type 1 MOT compacted 100-150mm. Expect to pay £15–£50 per m² for UK patio sub-base preparation.
What Does the Work Involve?
Excavate to 250-300mm depth below finished patio level. Lay Type 1 MOT (sub-base aggregate). Vibrate-compact to 95%+ density. Layer in 100-150mm. Surface level for slab/paving installation. Drainage falls 1:80 to drain.
Typical Costs
| Item | Low (£) | High (£) | Notes |
|---|---|---|---|
| Sub-base per m² | 15 | 50 | Type 1 MOT 100-150mm |
| Type 1 MOT per tonne | 30 | 80 | Material only |
| Excavation per m² | 10 | 30 | Plus disposal |
| Sub-base for 30m² patio | 500 | 1,500 | Standard install |
| Heavy-duty sub-base (vehicles) | +£20 | +£60 | Per m² |
| Geotextile membrane | 3 | 10 | Per m², optional |
| Compaction (vibrating plate) | 0 | 0 | Usually included |
How Long Does It Take?
30m² sub-base prep: 2-3 days. Larger: 3-5 days.
DIY or Professional?
DIY with care. Mini-digger and plate compactor hire. Most homeowners use specialist for quality.
Choosing the Right Tradesperson
Landscaper, groundworker, or paving specialist. APL member.
UK Regulations
SuDS principles for permeable surfaces. Building Regs Part H for drainage.
Common Problems
- Inadequate sub-base depth: Cheap installs skimp. 100mm minimum, 150mm for heavy use.
- Wrong material: Sand or gravel inadequate. Must be compactable aggregate (Type 1 MOT).
- No compaction: Loose sub-base settles. Vibrate-compact 95%+ density.
- Drainage falls wrong: Patio drains to house = damp. 1:80 minimum away from building.
Frequently Asked Questions
How deep should sub-base be?
Pedestrian: 100mm. Heavy use (vehicles): 150-200mm. Type 1 MOT compacted.
Sand or gravel sub-base?
Type 1 MOT (graded aggregate) only. Sand and pure gravel inadequate — won't compact properly.
Sub-base for typical patio?
30m² patio: 100-150mm Type 1 MOT = 3-5 tonnes aggregate. £150-£400 material.
Geotextile under sub-base?
Optional but recommended on soft soils. Prevents subsoil contamination. £3-£10/m².
Compaction essential?
Yes — without 95%+ compaction, patio sinks. Hire vibrating plate compactor £30-£60/day.
How long does sub-base last?
Properly installed Type 1 MOT: 50+ years. Becomes part of permanent landscape.
This guide was written with AI assistance and is intended for general information only. Prices are estimates based on UK averages and may vary by region. Always get at least three quotes and consult a qualified professional before starting any work.
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