Indoor Air Quality Monitoring for Condensation

Condensation is a common problem that affects many properties across the UK, and it is estimated that over 839,000 homes in the UK have problems with damp, the majority of these coming from private rented, local authority or housing association tenures (English Housing Survey 2020-2021).

Moisture production is caused by everyday living, from cooking to having a shower. Unless there is adequate ventilation, the moisture will remain in the atmosphere, and as the room air temperature drops, the ability for air to hold moisture reduces, and condensation will form on cool surfaces such as cold outside walls. This excess moisture can often be spotted in the corners of windows or around window frames, in or behind wardrobes and cupboards and often forms on cold north-facing walls. This is particularly common in solid wall properties where there is no cavity to stop the transfer of wind driven rain or cold to the living areas. This is known as condensation.

Sometimes the source of the condensation problem is difficult to understand, as it takes a delicate balance between ventilation, heating and insulation to create a welcoming atmosphere inside the property. This means that properties may suffer from condensation on one day, and then not for a few days. Even sensible changes like fitting double glazing or extra insulation can cause a property to shift equilibrium. This often occurs because adequate ventilation is not maintained and the property becomes warmer, but more humid as well.

Air monitoring systems can be used to collect data from inside the property over a period of time to fully understand the patterns of temperature and humidity that affect the formation of condensation. They are placed around the property, with the data collected used to help determine the root cause of the problem.

Peter Cox trained surveyors use diagnostics such as temperature and humidity levels to understand any issues, before identifying any areas that require attention. This is often carried out in partnership with a condensation survey, with all findings detailed in a survey report, along with recommendations to help prevent the condensation problem affecting the property.

When a property is suffering from a condensation problem it's important to understand the source of the moisture, and the areas most affected by the problem. This is different in every property due to the way it was built, the direction it faces in relation to the sun, and the efforts taken to reduce natural ventilation and draughts. This can make it more difficult to fully understand a condensation problem affecting a property, so having accurate information is a useful tool to provide a long term solution to the issues affecting the occupant.

Government guidance (Understanding and addressing the health risks of damp and mould in the home, 2024) suggests landlords consider “forms of physical testing, such as thermography” and “environmental monitoring” for complex cases of damp and condensation when identifying root causes of problems in tenanted premises. 

The report also states that “smart sensors may be a useful aid to monitor temperature, humidity and indoor air quality and to identify at-risk properties.” This makes air monitoring systems a useful tool for local authorities and social housing providers to fully understand issues facing their housing stock, while providing answers to the source of the issue, when a full condensation survey has been undertaken.

Moist stale air in homes can lead to damp walls, mould growth and can pose health risks for occupants. Sometimes wiping away mould will not solve the root cause of the problem and action must be taken to stop the condensation from forming in the first place. Often properties require improvements to ventilation, such as extractor fans being installed in bathrooms and kitchens, but in some cases there may be more complex issues causing the problem.

Using air monitors you are able to paint a picture of the internal environment within a home, identifying spikes in humidity, temperature fluctuations and other real time data that affect the air quality. Air quality monitors can be deployed and condensation surveys undertaken either between tenancies or during tenancies, depending on the issues being experienced.

As well as the indoor air quality report, our surveyor will complete a comprehensive condensation survey of the property with a detailed and thorough report of their findings. This will be presented in an easy to understand format, and will include recommendations if necessary, highlighting the need for any further remedial measures such as the installation of positive input ventilation (PIV units), extractor fans, topping up insulation or thermal plastering.

If you are concerned about condensation and mould in your home, or the housing stock that you manage, we can provide expert advice and solutions long term.

We can provide you with an expert condensation survey from experienced and specialist surveyors - with the right training and knowledge to fully understand the problems facing your property. Their findings in the report will be backed by evidence found using the air monitoring system, which can help build a holistic understanding of the condensation issues facing your property.

We have both CSRT and CSTDB qualified surveyors operating from a network of local branches across the UK who bring years of experience with them.

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  What is a condensation monitor?

  A condensation monitor is a device or series of monitors that are used to measure humidity, temperature, VOC's, CO2 and other relevant information at critical locations such as kitchens, bathrooms and bedrooms. The information gathered is then used to provide a solution to the problem through improvements to ventilation, heating or insulation. This means that a condensation or mould problem can be removed from the property in question.

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  How can you measure condensation?

  The conditions causing condensation to form in a property can be measured in several ways, but the two most important factors are the relative humidity (RH) within a property and the surface temperatures. The point at which condensation will form is known as the dew point. Air monitoring devices can be used to measure RH and the internal temperature in different rooms, providing an accurate understanding of when condensation is most likely to occur.

  Ultimately the best way to measure condensation in a property is to have a fully qualified surveyor carry out a condensation survey, as they are equipped with specialist tools which can be used to accurately diagnose the issues. Condensation often forms on cold surfaces at night when air temperature drops, but disappears during the day when air temperature rises and more moisture can be held in suspension. Constant monitoring is used to visualise these trends.

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  How to fix a condensation problem?

  To fix a condensation problem in your home you must either improve ventilation by opening windows, install extractor fans or PIV units, or make active steps to reduce the amount of moisture created. Sometimes condensation will form on cold surfaces, like uninsulated walls, so these may require thermal improvements such as thermal plastering. It is advisable to have a condensation survey to fully understand the problem affecting your property or housing stock.

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  Do humidity monitors work?

  Yes, humidity monitors work when placed throughout a property by using sensors to measure the amount of moisture in the air, and temperatures within the property. This data can then be analysed to understand what could be causing the problem, and provide recommendations to prevent condensation and mould growth in the future.

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  What are the symptoms of bad air quality in the home?

  The most obvious symptom of bad air quality within a home is the formation of black mould on cold surfaces, such as walls, windows, ceilings and furnishings. Symptoms of poor indoor air quality often include headaches, dizziness, eye, nose, and throat irritation.

  These issues can be of particular concern for the immunosuppressed, very young, elderly or those with a specific allergy. It can lead to reactions such as sneezing, coughing, and wheezing, or symptoms of respiratory issues like asthma. Moist stale air may also contain dust mite allergens and volatile organic compounds (from cleaning products, hair spray, deodorant, scented candles etc.), which can contribute to asthma symptoms.

  Awaab’s Law was brought in to help social housing providers address mould and damp problems, and provide preventative measures within strict timeframes.