The Hidden Threat of Elevated Ground Levels: A Local Morecambe Surveyor Perspective
As a residential RICS surveyor serving Morecambe, Heysham and surrounds, one of the most common damp-related issues I come across is where external ground levels are too high in relation to the property’s damp-proof course (DPC). A recent survey of a detached Morecambe bungalow highlighted this exact problem, with dampness found affecting an external corner of the building.
Identifying the Issue
During my inspection, I used a relative moisture meter to assess the internal wall at the affected corner. Elevated moisture readings were recorded up to approximately one metre high, with visual signs of dampness including peeling paint and minor plaster deterioration. Externally, it was clear that the ground level had been raised over time, likely due to landscaping and paving works, bringing it close to or above the DPC. This allowed moisture to bridge the protective barrier, leading to penetrating damp.
Why Does This Happen?
Over time, homeowners may unknowingly contribute to this problem by adding driveways, flower beds, patios, or paths without considering the impact on the property’s damp-proofing. If the ground level rises too high, moisture can bypass the DPC, resulting in damp issues internally. In bungalows, where the floor level is typically close to the external ground, the risk is even greater.
Risks and Consequences
Persistent dampness in walls can lead to:
- Deterioration of internal finishes – Plaster damage, paint peeling, and staining.
- Timber decay – Increased risk of rot in skirting boards, floor joists, and structural timbers.
- Mould growth – Leading to poor indoor air quality and potential health issues.
- Reduced thermal efficiency – Damp walls lose heat more quickly, leading to higher energy costs.
Recommended Solutions
To mitigate this issue, I advised the homeowner on the following remedial actions:
- Lower the external ground level – Ideally, the DPC should be at least 150mm above external surfaces to prevent moisture ingress.
- Improve drainage – Ensure that any hard landscaping slopes away from the property to divert water.
- Consider a French drain – Installing a gravel-filled trench or a perforated drainage pipe can help channel excess water away.
- Check for additional contributing factors – Blocked gutters, defective pointing, or bridging by render should also be addressed.
Final Thoughts
High external ground levels may seem harmless, but they can cause significant damp problems if left unchecked. As surveyors, it’s crucial to identify these risks early and provide practical solutions to homeowners in our RICS survey reports. Regular property maintenance, awareness of DPC positioning, and effective drainage measures can go a long way in preventing costly damp-related damage.
Why is this important?
Damp in residential properties in the UK refers to the presence of unwanted moisture within a building’s structure, which can lead to various issues, including damage to walls, floors, and ceilings, as well as potential health risks. It is a common problem in UK homes due to the climate, older housing stock, and poor ventilation.
Types of Damp in Residential Properties
- Rising Damp
- Caused by moisture from the ground moving up through porous building materials, such as bricks and mortar.
- Typically affects ground-floor walls and can result in peeling paint, stained plaster, and tide marks.
- Often occurs when the damp-proof course (DPC) is missing, damaged, or bridged by high external ground levels.
- Penetrating Damp
- Occurs when water enters a building through external defects like damaged roof tiles, cracked brickwork, faulty pointing, or leaking gutters.
- Usually appears as localized damp patches on walls or ceilings that worsen in wet weather.
- Condensation Damp
- The most common type of damp, caused by excess moisture in the air condensing on cold surfaces.
- Typically seen in areas with poor ventilation, such as bathrooms, kitchens, and bedrooms.
- Leads to mould growth, peeling wallpaper, and a musty smell.
Signs of Damp in a Home
- Peeling or bubbling paint and wallpaper
- Damp, discoloured patches on walls and ceilings
- A musty smell
- Black mould or mildew growth
- Cold or clammy walls
- Decayed timber (skirting boards, floorboards, or window frames)
How to Prevent and Treat Damp
- Improve ventilation – Use extractor fans, keep windows open when possible, and install trickle vents.
- Repair external defects – Fix leaks, clear gutters, and maintain pointing and brickwork.
- Use a dehumidifier – Helps reduce excess moisture in the air, especially in winter.
- Lower ground levels – Ensure external ground levels are at least 150mm below the DPC.
- Apply damp-proofing solutions – This includes injecting a chemical DPC or installing waterproof membranes where necessary.
Illuminati Surveyors – your trusted Blackpool surveyor serving Morecambe, Blackpool, Fylde Coast & Lancashire.
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Disclaimer: The information contained in this blog is provided for general guidance only and does not constitute legal, financial, medical, or other professional advice. No warranty, express or implied, is given as to the accuracy or completeness of the information. Reliance on any information provided is at your own risk.
