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Raised paving
New patios, driveways or paths installed too close to or above the original DPC line.
Bridged DPC specialists
High Ground Levels Causing Damp
Diagnosis-led solutions for paving, soil, render and other materials that bridge the damp proof course and allow moisture to affect internal walls.
- Source-focused repairs
- Surveyor-led service
- South West London & Surrey
Correct the cause
What is a bridged damp proof course?
A damp proof course is intended to interrupt moisture moving through masonry. When patios, driveways, soil, render or internal floor build-ups sit above or too close to it, moisture can bypass the barrier. This is known as bridging.
A commonly used construction benchmark is approximately 150 mm of clearance between external ground and the DPC. Thresholds, drains and older property details may require a tailored approach, so the surrounding construction should be inspected before work is specified.
What to look for
Common signs and bridging defects
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Soil against the wall
Flower beds, landscaping or accumulated soil holding moisture against masonry above the DPC.
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Bridged render
External render or coatings continuing below the DPC and creating a route around the barrier.
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Covered air bricks
High ground obstructing subfloor vents and reducing airflow beneath suspended timber floors.
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Poor falls or drainage
Hard surfaces directing rain towards the building or allowing water to pool at the wall.
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Low-level internal damp
Peeling decoration, stained plaster or salt deposits corresponding with high external levels.
Important: Similar symptoms can come from leaks, penetrating damp or genuine rising damp. Ground-level correction should follow an inspection of the whole area.
A proportionate solution
How high ground level damp may be corrected
Inspect & measure
Locate the DPC, compare internal and external levels and identify drainage, render and ventilation issues.
Choose the repair
Agree whether ground reduction, a paving cutback, render removal or a drained channel is appropriate.
Correct the bridge
Carry out the specified external work while protecting thresholds, services and surrounding finishes.
Repair finishes
Allow the wall to dry and replace damaged or salt-contaminated internal plaster where required.
Available repair options
Ground reduction, channels and French drains
The best option depends on available depth, drainage falls, thresholds, underground services and where collected water can discharge safely.
- Lower soil or external ground where practical
- Cut paving or concrete back from the wall
- Remove render or coatings bridging the DPC
- Form an appropriate drained channel where specified
- Restore or protect subfloor ventilation openings
- Repair affected internal plaster after the moisture source is addressed
Local property preservation
Bridged DPC solutions across South West London and Surrey
Atruss Preservation investigates high ground levels in Wimbledon, Wandsworth, Putney, Kingston, Sutton, Epsom, Banstead, Reigate, Weybridge and surrounding districts.
Related services
Repairs that may also be relevant
Frequently asked questions
Questions about high ground levels
How do high ground levels cause damp?
Paving, soil or other materials above or close to the damp proof course can let moisture bypass the barrier and affect the wall internally.
How much clearance should there be below a DPC?
A commonly used benchmark is around 150 mm. The appropriate solution still depends on thresholds, drainage, air bricks and the construction of the property.
Can a French drain solve high ground level damp?
A correctly designed drained channel may help where ground cannot be fully lowered. Its outlet, depth and maintenance requirements must be considered; a gravel-filled trench without effective drainage is not automatically a solution.
Is a new injected DPC always needed?
No. If an existing DPC is being bridged, removing the bridge or correcting drainage may be the primary repair. Injection should only be specified when supported by the investigation.
Will the internal plaster need replacing?
Plaster that has deteriorated or become contaminated with moisture-attracting salts may need replacement after the external cause is corrected. The required extent depends on its condition.
Concerned about high ground levels?
Call Atruss Preservation to discuss the wall, paving and drainage around your property.