Subsidence, Drainage & Patio Longevity in Godalming

What Do We Mean by Subsidence?

In simple terms, subsidence is the downward movement of the ground supporting a structure. In gardens, this can look like:

• Sunken or dipped patio areas.
• Cracked or stepped paving joints.
• Leaning or settled retaining walls.
• Gaps opening up between walls and paving.

In severe cases, subsidence can affect houses, but this guide focuses on garden and patio movement. Where house structures are involved, we will always recommend appropriate professional advice.

Why Patios Move in Godalming

Common causes we see across Godalming, Milford, Farncombe, Witley, Busbridge and neighbouring areas include:

• Insufficient sub-base depth under the patio.
• Poor compaction of sub-base or underlying soil.
• Clay shrink–swell driven by weather and tree roots.
• Waterlogging due to poor surface or sub-surface drainage.
• Old made ground settling under load.

Most of these problems can be avoided with correct ground preparation and drainage design. Our page on retaining walls & level changes also covers how supporting structures influence movement.

Clay Soils & Seasonal Movement

Clay-dominated areas like Witley, Milford and some lower-lying Godalming plots experience:

• Expansion in wet winters.
• Shrinkage in hot, dry summers.
• Additional drying from tree and hedge roots.

This can cause minor seasonal movement even in well-built patios, but poor construction amplifies the effect dramatically. For a deeper look at local soil behaviour, see Soil Types & Ground Conditions in Godalming.

The Role of Drainage in Patio Longevity

Water is one of the main enemies of long-term stability. Good design ensures:

• Water flows away from the property and key structures.
• No “ponding” areas where water sits on or behind the patio.
• Soakaways and French drains are used where appropriate.
• Retaining walls have adequate back drainage and weep holes.

Our separate guide Garden Drainage & Groundworks in Godalming explains these systems in more detail.

How We Build Long-Lasting Patios in Godalming

To maximise patio life, we focus heavily on three areas:

1. Sub-Base Specification

• Correct excavation depth (usually 150–250mm below finished level).
• Use of MOT Type 1 or similar, compacted in layers.
• Deeper build-ups on clay or made ground.
• Geotextile membranes where needed.

2. Proper Laying Techniques

• Full mortar bed for porcelain and stone.
• Priming slurry for porcelain slabs.
• Accurately maintained falls for surface water runoff.
• High-quality jointing materials appropriate to the stone and setting.

3. Integrated Drainage

• Channel or slot drains at thresholds.
• Falls leading to safe discharge points.
• Consideration of neighbouring properties and shared boundaries.

Warning Signs Your Patio Has a Problem

Look out for:

• Water pooling regularly on the surface.
• Slabs that rock or move underfoot.
• Visible dips, troughs or settled bands.
• Cracked or broken pointing, especially in repeated patterns.
• Soil washing out from edges after heavy rain.

Can an Existing Patio Be Saved?

It depends on what’s going on underneath.

Sometimes we can:

• Lift and relay certain areas with improved sub-base.
• Improve surface and sub-surface drainage around the patio.
• Repoint or re-joint surfaces where the structure is sound.

In other cases — particularly where the old patio has almost no proper sub-base — a full rebuild is the only long-term solution.

When Is Movement a Structural Concern?

Localised patio movement is usually a cosmetic and usability issue rather than a structural emergency. It becomes more serious if:

• Movement is close to the house foundations.
• Retaining walls supporting large level changes are leaning significantly.
• Cracks extend through walls, steps and building structures.

In such cases we may suggest independent structural assessment alongside any landscaping work. Our planning permission guide for Godalming also outlines when retaining walls trigger extra checks.

Designing for Longevity in Godalming Gardens

For new projects in Godalming, Milford, Farncombe, Witley, Busbridge, Charterhouse, Hurtmore and nearby villages, we always:

• Assess soil type and ground conditions.
• Look at tree positions and root influence zones.
• Consider drainage both on and below the surface.
• Specify realistic sub-base depths and reinforcement where needed.
• Match paving type (porcelain, sandstone, etc.) to ground conditions and usage.

The goal isn’t just to make the garden look good on completion day — it’s to ensure it still works years later.

Frequently Asked Questions

Can you build a stable patio on clay soil?

Yes. With proper excavation, sub-base, drainage and construction, patios can perform very well on clay soil. Many of our projects in Witley and Milford sit on clay and remain stable because the groundwork was done properly.

Will porcelain crack more than sandstone if the ground moves?

Porcelain is strong but less forgiving than some natural stones. That’s why good groundwork is even more important for porcelain projects, and why we often recommend deeper sub-bases and careful jointing.

How long should a properly built patio last?

Many well-constructed patios last decades, especially if drainage and groundwork are correct from the start and joints are maintained over time.

Can you fix a sinking patio in Godalming?

In many cases we can, either by lifting and relaying affected areas or rebuilding sections with better foundations and drainage. During a site visit we’ll assess whether local repairs are sensible or if a full rebuild is more cost-effective long term.

Which areas do you cover?

Godalming, Milford, Farncombe, Witley, Busbridge, Charterhouse, Hurtmore, Hambledon, Chiddingfold and the wider Surrey Hills area.

Concerned About Movement or Drainage in Your Patio?

If your existing patio is sinking, cracking or holding water — or you want to ensure a new patio is built to last — we’d be pleased to take a look and advise.

Arrange a Patio Assessment

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