Subsidence, Drainage & Patio Longevity in Farnham

Why Patios Fail in Farnham

1. Inadequate Excavation Depth

Many villages around Farnham have sandy soils (Lower Bourne, Rowledge, Frensham) that require deeper excavation to reach stable ground. Too many builders only dig 50–80mm — when 150–250mm is needed.

2. Clay Soil Movement

Upper Hale and Heath End sit on clay pockets which expand when wet and shrink when dry — causing patios to:

• lift in winter
• sink or crack in summer
• separate from edges or steps

3. Tree Roots

Roots from oak, pine and chestnut (common in Rowledge, Wrecclesham, Tilford) lift patios from below or remove moisture causing sinking.

4. Poor Drainage Design

• Wrong fall direction
• No channels where needed
• Insufficient soakaway capacity
• Patios built flat on clay

5. Sub-Base Migration (Sandy Soils)

Sandy soils shift without:

• Geotextile membrane
• Proper compaction
• Concrete haunching on edges

How We Build Long-Lasting Patios in Farnham

1. Correct Depth Excavation

We dig down until we reach stable ground — not just a shallow skim.

2. Reinforced Sub-Bases

• Type 1 for sandy areas
• Type 3 for clay or drainage-prone zones
• Geo-grid for unstable or steep slopes

3. Proper Drainage Strategy

• Falls of 1:60–1:80 depending on material
• Linear channels at property edges
• French drains near retaining walls
• Soakaways sized according to soil type

4. Full Mortar or Pedestal Installation

We never dot-and-dab porcelain or sandstone. Full-bed mortar ensures structural uniformity and prevents water pockets.

5. Concrete Reinforced Edges

All edges are haunched properly to prevent lateral spreading.

6. Root Zone Management

• Root barriers when needed
• Deep dig-outs around mature trees
• Soil stabilisation in moisture-variable zones

Recognising Early Signs of Patio Subsidence

• Pooling water in localised areas
• Slabs gradually separating or gapping
• Risers drifting out of alignment
• Edges sinking or lifting
• Visible dips or ridges

Subsidence Risk by Village

• Rowledge: Root-heavy, sandy ground → movement risk
• Wrecclesham: Mixed soils → varying stability
• Lower Bourne: Sandy → sub-base migration risk
• Frensham: Slopes + mature trees → root uplift
• Tilford: Moisture-variable zones → soft ground
• Upper Hale: Clay → shrink–swell movement
• Heath End: Clay → drainage critical

How We Prevent Sinking & Movement

• Geo-grid reinforcement where needed
• Deep compaction in layers
• Laser-levelled formation layers
• Drainage corrections and French drains
• Concrete foundations for steps and edges

Areas We Cover

Farnham · Lower Bourne · Wrecclesham · Rowledge · Frensham · Upper Hale · Heath End · Runfold · Tilford · Crondall · Ewshot · Boundstone

Concerned About Patio Movement or Subsidence?

If your Farnham patio is already moving, or you want to make sure a new terrace is built to last, we’d be pleased to visit, review the levels and ground conditions and suggest practical, long-term solutions.

Request a Site Assessment

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