Did you know that over a third of UK homes are considered poorly insulated? It’s no wonder so many of us are familiar with issues like recurring mould, discoloured walls, or persistent odours. Poor insulation and condensation issues often go hand-in-hand. So, if you’re seeing these effects, they often signal deeper problems. Consider these statistics:
- In 2022, around 11.5% of Scottish properties had damp or condensation problems.
- In Wales, about 600,000 people lived in cold and damp conditions in 2024.
- Northern Ireland had around 9,300 homes fail housing fitness standards due to damp in 2016.
- In England, about 3.8% of homes, or roughly 912,000 households, faced damp issues in 2021, and this
number is steadily increasing.
It’s easy to think of condensation as just a bit of water, but when it’s left unchecked this is the kind of trouble that it causes. Whether condensation and mould are problems that you’re facing personally, they’re causing trouble for someone you care about, or it’s just an issue you want to avoid in the future, this article is for you.
So, what is condensation, how can you spot early warning signs, and what can you do to stop it at the source?
What is Condensation?
Anytime warm, moist air comes into contact with a colder surface, the moisture in the air will cool rapidly, causing condensation. You’ve likely observed this in everyday situations, such as the fog on your bathroom mirror after a shower or the water running down your kitchen window after cooking a hot meal. Condensation is around us all the time!
This process is particularly common during winter, when we take warmer baths, dry wet clothes on radiators, and generally spend more time keeping warm indoors. You may notice water droplets accumulating on your window panes, doors, walls, or tiles during cold mornings. This is because cold air from outside enters the warm interior, cools down, and releases moisture, which appears as the water droplets you see on these surfaces.
However, condensation becomes more problematic when it occurs unexpectedly and in areas not designed to handle it.
For instance, while bathrooms are built to manage some level of condensation and are typically well-ventilated, other areas like bedroom walls are not.
When condensation on walls happens, it can lead to issues such as damp patches, peeling wallpaper, discoloration, and mould growth. Over time, this accumulated moisture can damage your home and negatively impact your health.
It’s essential to understand that once you start seeing mould, your property faces much costlier repairs. It’s a difficult, expensive, and often an overwhelming process to completely eradicate mould growth, manage and resolve moisture issues, and finally restore your home to good health; all of which goes to show how dangerous condensation can be and how it can limit your chances to have a warm, safe, and comfortable home.
Common Conditions That Promote Condensation
From simple day-to-day activities such as cooking, showering, and even breathing, to functional issues in your home, such as poor insulation or a lack of ventilation, there are plenty of potential causes for condensation.
However, if you understand what causes condensation, you can take proactive measures to prevent it and protect your home. So, let’s take a look into some of the most common contributors to condensation and what you can do about them.
High Humidity and Poor Ventilation
When moist air isn’t properly vented, it can accumulate and condense on cold surfaces. Our day-to-day activities constantly raise the level of humid air inside the home, and kitchens and bathrooms are particularly vulnerable due to activities like cooking and showering. With inadequate ventilation, there is no way for the humid air to leave your home, meaning condensation issues are inevitable.
Solution:
1. Keep windows and vents unobstructed. Use dehumidifiers, extractor fans, and trickle vents to keep humidity levels low.
2. Another brilliant solution is to install a Mechanical Ventilation with Heat Recovery (MVHR) system to keep the air in your home fresh, clean, and moisture free.
Lack of Insulation
As mentioned earlier, condensation often occurs when there’s a significant temperature difference between indoor and outdoor environments. This is only an issue if your home is not well insulated or the insulation is affected by thermal bridging.
Insulation acts as a barrier, restricting heat loss or gain, and keeps the property at an even temperature all year round. A lack of insulation will promote temperature differences and allow more moisture to creep in through your walls and cool down on the surface.
Solution:
1. Insulate your property, including pipes and ducts, well enough to minimise temperature differences.
2. Ensure continuity in insulation
Poor Installation
Lack of Vapour Barriers or Breathable Membranes
When insulation is not installed correctly, gaps can form between the insulation and the building, allowing cold air to enter and mix with warm, moist indoor air. This is especially common around windows, doors, and other openings in the building, which can be especially difficult to insulate well.
Additionally, if insulation is not properly supported, it can sag, leaving parts of the building exposed to temperature differences.
Improperly sealed vapour barriers or breathable membranes can also cause problems, as they let moisture pass through walls and ceilings. In most cases, this is how insulation ends up absorbing moisture, which compromises its effectiveness and could potentially even lead to mould growth.
That’s not all, there are many other ways to choose the wrong kind of insulation for the job, for example:
- Using absorbent insulation, such as fibreglass, in
humid areas without a vapour barrier. - Using a shed conversion insulation product to
insulate walls or roofs that require much higher
thermal performance.
Any time an insulation product or installation technique fails to meet the recommended thermal performance, moisture management, or installation standards, it will eventually lead to problems with the property. These could be temperature differences, condensation, damage to the structure, and in many cases it is all of these and more.
Solutions:
1. Ensure insulation is not compressed and is the appropriate thickness for the space, especially in tight areas like attics and walls.
2. Hire qualified professionals to install insulation properly and eliminate gaps. If you need help finding an installer, get in touch with us.
3. Adhere to manufacturer instructions regarding thickness, coverage, and installation techniques.
4. Use appropriate low-emissivity tape or sealant to tightly seal all joints and edges of vapour barriers.
5. Choose insulation materials suited to the climate and specific purpose of application within the building.
Vapour control solutions such as vapour barriers and breather membranes are key elements of any insulation build up. If you are installing insulation internally, you want to avoid moisture created by everyday tasks from getting through the insulation and into the fabric of the building.
Similarly, if you are insulating externally, you want to prevent water from rain or fog from passing through the insulation and causing damage. However, not all insulation types are vapour-resistant or even watertight, which means they risk becoming partially or completely ineffective once wet.
What’s worse than losing its thermal properties is that they promote interstitial condensation, which is an issue where condensation occurs within the building structure itself (walls, roofs, or floors)! The thing that makes interstitial condensation so dangerous is that it may not be immediately visible from the outside, making it hard to recognise and address. Learn more?
Solution:
1. For any insulation without an integrated Vapour Control Layer, make sure to add an external membrane to secure your home.
SuperFOIL has a range of Breathable and Vapour control multifoil products with integrated membranes, ensuring a continuous, watertight, and well-sealed insulation system in one product. This means you don’t have to worry about purchasing or installing additional membranes.
Watch how we install our Vapour control product SF40 under the rafters and Breathable SF40BB over the rafters.
Failing To Seal Gaps And Cracks
Any opening in your home is a condensation risk. However, gaps and cracks in your insulation build-up are particularly risky, because these are openings that aren’t supposed to be there. You can’t monitor and address the condensation caused by these issues, because you won’t know to look for it, and in many cases this condensation will be happening in areas you can’t even see!
Solution:
1. Choose insulation products that reduce or eliminate repeating cold bridges and make a continuous insulation envelope easy to achieve. Multifoil insulation such as SuperFOIL is a perfect choice to assist here.
2. Use cavity closers to close gaps around windows and doors in cavity-wall construction to minimise temperature difference caused by thermal bridging.
Water Leaks
Any water leaks from broken pipes, or damaged gutters can allow water to penetrate the building’s fabrics and can eventually lead to major damp patches that spread across the property rapidly.
Solution:
1. Identify broken pipes, blocked gutters, gaps, cracks and any other plumbing related issues and be sure to fix it immediately to keep water from reaching your insulation along with other building elements.
Struggling to find the right product?
Don’t worry, we’re here to help! Our team is always available to give a hand with product recommendations, build-up solutions, U-value calculations, condensation risk analysis, or even a free discovery session. All our services are entirely free of charge, and our experts are always here to help you achieve the best results.
Now, if you’re an installer or a builder, you might also want to consider taking part in our free insulation certification programme? It’s a great programme, assuming you want to learn more about multifoil insulation and how you can earn a little extra cash too!
Learn more about our Approved Installer Programme here: https://www.superfoil.co.uk/services/approved-installer-programme/
Answering Your Questions About Condensation & Insulation
1. Can insulation cause condensation, damp and mould issues in your home?
Insulation on its own cannot cause condensation. However, the right insulation product used in the wrong way could end up contributing to condensation issues. For example, insulation being improperly installed such as too many layers fitted on top of each other or if it is too tightly packed, installing without appropriate ventilation, or a non-breathable and non-watertight product used externally on the roofs are all examples of poor installation practices that will invite condensation. If you are not familiar with installing insulation, make sure to trust your project with experienced and professional installers.
2. Can minimising condensation improve energy bills?
Minimising condensation can improve energy bills! Keeping a damp and leaky property warm is hard. So, taking care of those issues will make it much easier to heat the property and retain warmth. This minimises the need for prolonged heating in winter, saving energy and reducing your electricity bills.
3. How much insulation is too much insulation?
In the UK, achieving the appropriate level of insulation in a building is not just about the quantity of insulation material but about reaching specific U-values, which measure how effective the insulation is at stopping heat loss. The lower the U-value, the better the material is at insulating. To know more about specific u-value requirements, visit our building regs page. To get your own customised calculations, Visit our u-value calculations page.
4. How do I know what product is right for my old home?
The way houses are built over the years has changed, and many insulation types have evolved to adjust to that demand. For instance, if your home is old and built on a porous or vapour-open wall structure, they could naturally absorb and evaporate moisture out. This means any insulation you choose for this property should be vapour open or, in other words, breathable to allow moisture to escape outside freely. However, if your property is a moisture-closed structure, using breathable insulation could be a mistake, and you need a product that ensures a high level of vapour resistance on the warm side of the construction.
5. What are the health risks of damp?
People exposed to damp or mouldy environments may experience respiratory issues like coughing, wheezing, and even asthma attacks. Worse, damp environments could lead to mould growth, which could also trigger allergic reactions such as sneezing, skin rashes, and irritated eyes.In more severe cases, prolonged exposure to dampness and mould can weaken the immune system, making individuals more susceptible to infections; young children, the elderly, and those with existing health conditions are particularly susceptible to this risk.
According to the “Health inequalities: cold or damp homes” report published by the House of Commons Library, the NHS spends an estimated £1.4 billion on treating illnesses associated with living in cold or damp housing, each year.
6. Who is responsible for damp or moisture related problems in a rented property?
In a rented property, the landlord is generally responsible for addressing damp or moisture-related problems. However, tenants also have a role in managing and minimising vapour and condensation occurring from their daily indoor activities.
If dampness is due to structural issues, like a leaky roof or inadequate ventilation, it is the landlord’s responsibility to fix it. Tenants should promptly report any signs of damp or mould to the landlord to allow for timely repairs.
7. What are landlords’ responsibilities?
Landlords are responsible for identifying and fixing the underlying causes of mould or condensation problems in their properties. This may involve making structural adjustments, such as improving insulation and ventilation, to protect tenants’ health.
Landlords should also communicate with tenants about how to minimise condensation through everyday actions, like using extractor fans and keeping rooms ventilated. By addressing these issues, landlords ensure a healthier living environment for their tenants.
