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How to Measure Dampness in Walls

Have you ever noticed unsightly stains on your walls or a musty odour in your home? If so, you may be dealing with the common issue of rising damp. This problem can cause extensive damage to your property if left untreated. But how can you detect rising damp in the first place? The answer is simple: moisture metres. In this ultimate guide, we’ll explore how to measure wall dampness using moisture metres. From understanding the causes of rising damp to selecting the right moisture metre and interpreting the results, this guide has everything you need to know. So, let’s get started and learn how to protect your home from the damaging effects of rising damp.

Understanding Dampness in Walls

Dampness in walls can manifest in various forms, such as rising damp, penetrating damp, or condensation. Each type has its causes and signs but typically results from excess moisture entering the walls from either external sources or internal activities. In London, the combination of historical buildings and rainy weather exacerbates the problem. Recognising the early signs of dampness, like mould growth, peeling wallpaper, or a musty smell, can prevent more severe damage.

The Importance of Measuring Dampness

Neglecting dampness in your property can have several adverse effects on your health and your house’s structure. Dampness can lead to the growth of mould and other harmful microorganisms that can cause allergies and respiratory problems. In addition, the moisture can weaken the structure of your property, leading to potential structural damage. 

Understanding the extent of dampness within your walls is essential to ensuring your property’s safety and well-being. Only by addressing the root cause of the dampness can you prevent future occurrences and safeguard the integrity of your property.

Tools for Measuring Dampness in Walls

Dealing with damp weather in London requires keeping walls free from moisture to prevent mould growth, structural damage, and reduced thermal efficiency. Various tools and methods are available to measure dampness in walls. Here are some of the most effective ones:

Moisture Metres

These are perhaps the most common and straightforward tools used to measure the moisture content in walls. Moisture metres come in two main types: pin-type and pinless. Pin-type metres measure moisture at various depths by inserting pins into the wall, while pinless metres use electromagnetic sensors to measure moisture without causing any damage to the wall surfaces.

Thermal Imaging Cameras

Also known as infrared cameras, these devices detect temperature variations on the surface of walls, which can indicate the presence of moisture. Since damp areas tend to be cooler, thermal imaging can highlight potential issues that are not visible to the naked eye.


These instruments measure the relative humidity in the air, which can be a useful indirect measure of dampness in walls, especially when used in conjunction with other tools. High levels of humidity in a room can suggest that there may be excess moisture within the walls.

Calcium Chloride Kits

This is a more traditional method, which involves placing a measured amount of calcium chloride in a small dish, exposing it to the air in a room (typically on a flat surface against the wall), and then weighing it after a set period to determine how much moisture it has absorbed from the air. This method is more commonly used for floors but can also be applied to walls, especially for diagnosing dampness issues in concrete and masonry.


A borescope is an optical device consisting of a rigid or flexible tube with an eyepiece on one end and a lens on the other. It can be inserted into small holes drilled into the wall to look for signs of moisture or damage inside the structure without causing significant damage to the wall.

Chemical Moisture Detectors

These tools use chemical indicators that change colour when they come into contact with moisture. They can be used directly on the wall surfaces or within drilled holes to detect the presence of water.

To use damp measuring tools effectively, it’s crucial to understand how they function and what the readings indicate. It’s wise to consider engaging a professional surveyor or damp specialist if you suspect a significant damp issue. 

In London, where historical buildings are prevalent, it’s essential to approach damp measurement and treatment with caution to avoid causing damage to valuable or delicate structures. 

How to Prepare Your Wall For Dampness Measurement

Before you start measuring the dampness in your walls, it’s crucial to prepare adequately to ensure accurate readings and to protect the structure of your building, especially if it’s an older or historical property.

Visual Inspection: Begin with a thorough visual inspection of the affected area. Look for signs of dampness such as peeling paint, mould growth, staining, or salt deposits. Note the areas where these signs are most apparent.

Clear the Area: Remove any furniture or obstacles from the area where you plan to measure dampness. This ensures that you have full access to the walls and can get accurate measurements.

Choose the Right Time: The best time to measure wall dampness is during or after the rainy season, when walls are most likely damp. However, avoid measuring immediately after heavy rain, as external walls may be wet, which could skew your readings.

Select the Appropriate Tools: Choose the most suitable tools depending on the severity and nature of the dampness. For a general assessment, a moisture metre might suffice. For more in-depth analysis, consider thermal imaging cameras or borescopes.

Safety Precautions: If you’re using pin-type moisture metres, ensure you have the necessary equipment to repair any small holes you make in the walls. Wear protective gloves and eyewear when handling tools and inspecting potentially mould-infested areas.

Step-by-Step Guide to Measuring Dampness

  • Start with a Moisture Metre: Begin by using your chosen moisture meter. For pin-type metres, insert the pins into the wall at various heights and locations, starting from the bottom (near the floor) and moving upwards. For pinless metres, press the device against the wall at different points.
  • Record the Readings: Take note of the moisture level readings in different parts of the wall. Compare these readings to the normal moisture levels for your type of wall material.
  • Use Supplementary Tools: If necessary, use a thermal imaging camera to identify cooler, potentially damp areas that were not detected by the moisture meter. Use a borescope to inspect inside the wall if you suspect internal issues.
  • Map the Dampness: Mark the areas of dampness on the wall with non-permanent markings to help visualise the extent and pattern of the dampness.
  • Confirm with Secondary Tools: Cross-verify areas of high moisture with other tools like a hygrometer or calcium chloride kits to ensure accurate readings.

Step-by-Step Guide to Using a Moisture Metre

Correctly using a moisture metre starts with calibrating the device according to the manufacturer’s instructions to ensure accurate readings. For timber, gently insert the pins of the metre into the wood; for masonry, place the sensor flat against the plaster, mortar, or brick. Move the metre across different areas to gauge the total moisture content, paying special attention to places where high readings might suggest water ingress. Always measure moisture at various heights to track the moisture level effectively, as this can help pinpoint sources of dampness, such as rising damp or penetrating damp.

Interpreting the Results: What Does the Moisture Level Indicate?

Understanding metre readings is essential for diagnosing problems. A high moisture reading in timber could indicate excess moisture that may lead to decay or fungal growth. In masonry, persistently high levels of moisture may signal capillary moisture content, a characteristic sign of rising damp. Comparing these results to baseline or “normal” moisture levels for the specific material under similar environmental conditions will help determine the severity of the damp problem and the urgency of remediation efforts.

The Importance of Professional Damp Assessment Over DIY

The significance of professional damp assessment over DIY methods cannot be overstated, particularly when dealing with complex or extensive damp problems. Professionals offer a wealth of experience, accuracy, and access to advanced diagnostic tools that the average homeowner lacks. 

When you choose Environ Property Services, we will determine the exact cause of any dampness in your property. Whether it’s due to a hidden leak, poor ventilation, or a structural problem, we will identify the root of the issue and apply the appropriate treatment. This not only saves you time and money in the long run, but it also ensures the structural integrity and health of your property. Our professional assessment is a valuable investment that you won’t regret.

Environ Property Services: Reclaim Your London Property From Damp

Is persistent dampness turning your London home into a health hazard? Don’t wait any longer! Environ Property Services is here to help you breathe easy with our expert damp-proofing solutions.

Why Choose Environ Property Services?

  • Damp Survey: We start with a thorough inspection to pinpoint the exact cause of your damp problem.
  • Expert Diagnosis & Solutions: Our highly trained professionals don’t just treat symptoms – we tackle the root cause for a long-lasting fix.
  • Family-Owned & Customer-Focused: We treat your property with the same care we would our own, prioritising excellent service and clear communication.
  • Advanced Techniques & Proven Results: We use industry-leading methods to combat all types of dampness, from rising dampness to condensation.
  • Comprehensive Services: We offer a full range of solutions, including timber proofing, basement waterproofing, and woodworm treatment.

Request your Damp Survey Today! Let us create a healthier, happier living environment for you and your family.

How Moisture Affects Timber and Masonry

Moisture can severely affect the structural integrity of buildings. In timber, it can cause warping, swelling, and eventually decay. Similarly, masonry is not resistant to moisture and can freeze in cold weather, leading to cracking or contributing to the breakdown of mortar. Some materials are hygroscopic, which means they absorb moisture from the air, worsening damp problems.

The Role of Ventilation in Managing Humidity and Damp

Ensuring effective ventilation is crucial for managing indoor humidity levels and preventing condensation, a common source of moisture that can exacerbate building damp issues. To reduce the risk of dampness, it is recommended to ensure that air circulates freely by using extractor fans in areas like bathrooms and kitchens and opening windows regularly. Following these steps can significantly reduce the risk of dampness in your building.

Frequently Asked Questions

What types of moisture metres are best for detecting dampness in walls?

There are two main types of moisture metres: pin-type and pinless. 

Can I use a moisture metre to measure different wall materials?

Yes, moisture metres can be used on various wall materials, including plaster, brick, and wood. However, for accurate readings, it’s essential to calibrate the metre according to the type of material. Some metres have settings specifically for different materials.

How do I know if the moisture level in my wall is too high?

Moisture levels vary depending on the material and environmental conditions. Generally, a reading above 17% in wood is considered high, while in masonry, any reading above 5% could indicate dampness.

Final Thoughts

Measuring dampness in walls with moisture metres is crucial in protecting your property from the adverse effects of rising damp. By understanding the causes of damp, selecting the right tools, and accurately interpreting the results, you can effectively identify and address dampness issues. Early detection and intervention are key to preventing structural damage and health problems associated with damp walls. If you’re unsure about your moisture metre readings or how to tackle the dampness, don’t hesitate to get professional help. Contact us today for a damp survey!

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