From Damp to Mould – Your Guide to Keeping Your Home Healthy

The fabric of a building can be damaged by all sorts of factors, many of them related to the British weather – we’re getting used to increasingly cold and wet winters and boiling hot summers, as climate change has its way. If not dealt with promptly, issues such as condensation and leaks can lead to destructive conditions such as mould, which can affect both the health of a building and that of the people who live in it. Worse, catastrophic events such as floods and storms can cause major damage overnight, and without planning, can take months or years to repair. So how can we take care of the health of our buildings as well as we do our own?

The answers start with the basic design of structures. It’s widely accepted that airtightness and moisture control are two of the most important parts of building design. Air barrier systems in the form of airtight membranes are suitable for use both on-site and also in offsite construction methods. Typically installed on the inner side of the insulation within external wall and roof structures, these airtight membranes have a dual purpose; to restrict the flow of moisture from inside a building into the fabric, and to create an airtight layer on the internal envelope of a building.


Moisture is an inevitable result of having people living in a building – it’s generated through breathing, cooking and washing. When this warm moisture vapour passes into the fabric of the building and cools down within the structure, so-called interstitial condensation can occur. This can cause a number of problems, from promoting mould and structural damage to reduced thermal performance. Part of the solution to the moisture problem lies in airtight construction. When there are no unintended gaps in the building envelope that allow air to leak in or out of the building, we avoid reducing the energy efficiency of a building that can create a draughty, unhealthy, uncomfortable building environment.

Fire-rated non-combustible membranes can enhance the building’s fabric in terms of airtightness, energy efficiency and moisture management, while providing exceptional fire safety to the building and its occupants, particularly where where high levels of fire performance are desirable or mandatory, such as high-rise projects, public buildings, hospitals, hotels and universities. Some ‘smart’ membranes are designed to intelligently control moisture vapour, summer drying conditions but equally protecting the construction in winter.

In cases where water damage is caused by leakage, leak detection systems can prevent extreme damage in the first place, or can locate sources of leaks to minimise damage after the event. There are many different possible sources of water leaks in a building; anything from exterior water mains to central heating or underfloor heating, hot or cold water systems, ground source heat pumps and loft water tanks to swimming pools or spas. Specialist leak detection equipment can detect leaks through all types of internal floors or external hard surfaces including concrete and tarmac, outdoors in fields or open spaces, under landscaped gardens and even under buildings. In sealed systems such as heating circuits and heating systems, tiny invisible leaks known as Micro Leaks can result in a slow and constant loss of pressure in the system with no obvious cause. Micro Leaks tend to occur more often in heating circuits and hot water pipes, and as the water is hotter, it evaporates far more quickly leaving little or no trace. The constant loss of pressure will eventually lead to a boiler breakdown. Finding, diagnosing and repairing these leaks will ensure that your heating system won’t fail you when you need it the most.


A water leak outside or on the ground floor can be there for a long time without being spotted, and water mains and cold feed supply pipes can leak freely with no surface evidence while causing enormous damage to a property. Remember that the feed pipe from the water main to your home is usually your responsibility, not that of the water supplier. If you have a water meter and you find that your usage shoots up unexpectedly, you may have an exterior leak, which if not shut down promptly could land you with a large bill.

Specialist leak detections services can use a wide variety of technologies to find the source of a problem without knocking holes in your walls and floors, including ultrasonic devices which can listen for exact leak locations up to 2.5 metres below the surface, tracer gasses, a safe mixture of hydrogen and nitrogen forced into pipework at safe working pressures, with gas sniffers then pinpoint the leak location, damp meters which can detect damp and moisture from up to 2.5cm behind the surfaces of floors and walls, and endoscope cameras, small diameter ‘snake’ cameras which can see for instance behind bath panels, into boxing, and into voids in floors, ceilings and walls.]

Another problem which can lead in the long term to health problems for both people and properties is humidity, the amount of water vapour present in the air. Excess humidity can lead to growth of mould and mildew, and even structural damage, particularly to wood. Mould can even grow in carpets and can be hard to eliminate. On the other hand, excessively dry indoor air can lead to warping or cracking of wood furniture and building materials. The recommended humidity level for dwellings is 40-59 per cent. The most important percentage to remember is 60 percent relative humidity – at this point your home becomes a veritable incubator for bacteria and virus growth. In the winter you can lower humidity by raising air temperature or running fans to improve air circulation. Ventilator fans in the kitchen and bathroom can be left running for 15 minutes or longer to clear out lingering moisture. For better control of humidity, dehumidifiers can control humidity levels in the home, workplace and other indoor areas such as swimming pools, garages and boats.


A dehumidifier is usually used for comfort or health reasons, as well as protecting cars, caravans and other equipment from mould, rust and deterioration due to excess humidity. The six signs that you need a humidifier in your home are: Condensation on windows and glass doors, mould spots on walls, rot on wooden floors and furniture, musty smells, allergy symptoms such as sneezing and watering eyes, and visible water damage to ceilings and walls.

Dehumidifiers can prevent mould growth and stop the moisture from reducing the lifespan of window frames or bathroom ceilings and walls, and have a range of other health benefits too. Air at a controlled lower humidity is easier for people suffering from asthma to breathe, and also reduces the number of asthma triggers such as dust mites. Many humidifiers are fitted with filters to capture fine impurities in the air and to disrupt microbe reproduction. Dehumidifiers can also reduce energy costs; due to the reduction in water particles in the air, lower humidity levels allow for significantly cheaper heating during winter months as you can run the heating less and at a lower temperature. During summer months, dehumidifiers can be paired with air conditioning systems units to control the temperature of your home more effectively and cost-efficiently.

Iain Mantrippe of The Dwelling Doctors ( says: “Few problems are as interconnected and potentially hazardous in the realm of home maintenance and health as mould, condensation, and inadequate ventilation. Moisture is the primary cause of indoor air quality problems, and insufficient ventilation traps moist air inside, providing an ideal breeding ground for mould and mildew.

“Mould is not just unsightly, unpleasant-smelling, and damaging to wall coverings, furniture and carpets; it is also a health hazard. Mould spores can trigger respiratory issues, allergies, and asthma attacks, especially in vulnerable individuals such as the young, elderly, or those with pre-existing health conditions.

“Effective ventilation is the key to successfully tackling issues related to moisture accumulation and condensation. In high-moisture areas such as kitchens and bathrooms, it is crucial to have extractor fans that can efficiently exhaust moisture at the source.

“Tackling the issues of mould and condensation requires a proactive approach. By addressing the root causes and employing effective ventilation measures, we can protect our homes and health from the numerous problems these conditions can cause”.


The UK is experiencing a year-on-year rise in homes requiring treatment for damp and mould, with some areas seeing an unprecedented spike in residential properties experiencing this problem. Overall local authorities have seen a huge 66.67% rise in complaints during 2022/23 compared to the year before and housing associations saw a 70.23% increase during the same time period (USwitch Mouldy Nation Report.) Mould can spread fast, causing expensive structural damage, so start to treat the problem straightaway. A professional mould removal company will charge you from between £300-£400 per day to solve the problem and a painter and decorator will cost you another £200-£300 per day to ensure your rooms are permanently mould free. Plumbers’ prices can vary widely depending on where in the UK you are anywhere up to £500.00 per day.

To effectively remove mould, use HG mould remover ( to deal with the issue head on. HG mould remover eliminates all mould and is suitable for a wide range of surfaces including plastered walls, tiles, bathroom seals and more. With a targeted spray action HG mould remover is easy to use directly onto mould or mildew in damp areas. Damp can contribute to wood rot, either wet rot and dry rot, which are caused by fungal decay in building timbers. If you do have these problems – or an infestation of woodworm, the larvae of wood-boring beetles which like damp conditions – it’s time to call in the specialists. Treating woodworm and rot can be as simple as a chemical spray, but it can become necessary to replace structural timbers within a property. ■

This feature was originally published in Property & Home With Martin Roberts, Spring/Summer 2024. See more here

See also: The Best Quiet Washing Machines for Your Home

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