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14 Ways To Help Reduce Condensation In Your Property

By EnviroVent Oct 10, 2014

Condensation on windows occurs because water vapour in the air deposits itself on surfaces that are at lower temperatures. When moist air comes into contact with the cold impermeable surface of your windows, it releases some of this moisture onto the glass as water droplets. This is condensation.

Condensation occurs when warm air collides with cold surfaces, or when there's too much humidity in your home. Condensation is caused by airborne moisture, millions of minute particles of water suspended in the air. When it comes into contact with a colder surface like glass, a cold ceiling or wall, it reaches dew point and turns back into water droplets. When it meets the cold glass of your bedroom windows, the air becomes unable to hold so much moisture, which condenses. Condensation is the result of hot and humid air coming into contact with a cold surface. When this warm, moist air meets this too-cold surface, the moisture in it condenses. In the medium to long term, condensation may cause mould and peel off the paint on the edges of your windows. The cures for condensation are heating (to keep surfaces above dew point temperature) and ventilation (to expel the warm, moisture-laden air to the outside).

Condensation on windows occurs because water vapour in the air deposits itself on surfaces that are at lower temperatures. When moist air comes into contact with the cold impermeable surface of your windows, it releases some of this moisture onto the glass as water droplets. 

There are three basic ways to control the problem of condensation, by looking at relative humidity, ventilation and insulation:

  • Control humidity. Control the relative humidity in your home through the use of extractor fans in kitchens and bathrooms.
  • Provide ventilation. Or ensure there is adequate ventilation.
  • Add insulation.

Damp can cause mould on walls and furniture and cause wooden window frames to rot. It's also unhealthy. Some damp is caused by condensation. Condensation occurs when moist air comes into contact with a colder surface like a wall, window, mirror etc. The air can't hold the moisture and tiny drops of water appear. Moisture in the air will form condensation (droplets of liquid water) when it comes into contact with a cold surface such as a window. Ventilate so the moist air leaves the house – always use the extractor fan when you're cooking, showering or bathing, leave any window vents open, and don't block off any other vents.

This moisture can build up and form patches of mould. It might help to occasionally wipe down walls and window frames with a fungicidal wash. If you're removing mould caused by condensation, the NHS recommends that you wipe it away with a cloth dipped in soapy water. When you're done, use a dry cloth to remove any moisture, and throw both cloths away. 

Most damp walls in modern housing are caused by condensation. You can usually tell by the pattern of the damp and damage, but do not be fooled by the amount of water involved. Some people think they must have a leak because their walls are so wet, but condensation can release a huge amount of water, so that is not a good gauge of whether the problem is condensation or water ingress.

Condensation inside double glazing   

A key condensation culprit are windows, condensation around windows can be hard to keep on top of especially when raining as rain will  inevitably leave water marks on windows. The best way to keep on top of condensation around windows is to be on the look out for any damage to the sealant around the windows as this will allow water in. Try to wipe down window sills to ensure no excess moisture enters your property's air and open windows as often as possible to allow air to circulate. 

Rooms like kitchens and bathrooms are optimum environments for condensation, as bathrooms are usually wet, damp  and moist. Showering and bathing inevitably cause water droplets to form on walls and windows and if not properly ventilated and dried quickly, linger and cause excess moisture to form. The warmth from the steam also keeps the condensation, which you can mostly see on bathroom windows. It is very difficult to keep on top of condensation in bathrooms as the biggest prevention is ventilation which is something that can be hard to create and maintain in bathrooms and kitchens. 

Condensation on bedroom windows maybe noticed last, especially if it is a room not used very often. Signs to look out for with condensation around bedroom windows are; water on the window sill, damage to window frames and it is also important that you don't ignore black mould on soft furnishings like curtains or cushions.  

Interior window condensation is caused by excessive moisture in the house, and it often occurs in the winter when the warm air inside the house condenses on the cold windows. Condensation between window panes occurs when the seal between the panes is broken or when the desiccant inside the windows is saturated. Exterior window condensation is simply dew and occurs when the window is colder than the dew point. However can you get condensation on double glazed windows?

While condensation can be worse on single glazed windows (due to the internal surface of the window being much colder than the internal surface of a double glazed window) replacing single glazed windows with double glazing is not enough to eliminate the problem. The reason being is that although the inside of your new windows will be warmer, they will simultaneously eliminate draughts. This will reduce ventilation, and contribute to the build-up of moisture. 

Whilst this does not happen often, condensation can form on the outside pane of a double-glazed window. When it does, it is usually because the unit is performing well and very thermally efficient. It is not an indication that there is anything wrong.The reason it happens is because the external air is warmer than the temperature of the glazed pane’s surface – and the dew point of the air is higher. It is more likely to occur at night or early in the morning when temperatures are low, particularly if there is a clear sky and almost no wind.

Although it can be a pain to have limited visibility until the condensation on the outside pane clears, it’s a good sign that your windows are extremely energy efficient and constructed using low-emissive glass. If you do want to eradicate the issue, there are a few simple steps you can take.

The first is to allow more air and wind to flow past your windows, as this will reduce the chances of this condensation forming. To prevent the window’s surface area from cooling to the point where condensation forms, you could consider creating more areas of shading as this can help to retain warmth. Positioning tall trees, shrubs, plants or some form of shelter may help you do this.

Could the double glazing be faulty?

Condensation within double glazing typically suggests that there is a problem with the sealed unit of the windows. This means that a point in the edge seal of the window has failed and is allowing moisture enter in the form of condensation. This form of moisture/condensation in double glazing is often the sign that the sealant between the glass and frame will have to be renewed. 

On older or poorer quality units, the sealant used to create the seal (around the windows) may be of a low grade or become loose over time. If the seal and bead that’s supposed to hold the glass in the frame deteriorates, moisture and water can get into the frame. Allowing large amounts of water to settle in the frame like this for a long period of time will eventually affect the ‘air gap’ seal surrounding the two panes of glass.

Sometimes, the uPVC frames themselves will crack and allow water to gather. Another reason why you may see condensation in double glazing is because of a fault with the ‘spacer’ bar. Most double-glazed windows now feature a ‘spacer’ in between the two panes of glass and this is full of desiccant, a highly-absorptive material which sucks up any moisture in the ‘air gap’ void.

If there is even the slightest imperfection in the seal, this desiccant can quickly become saturated by any moist air or water which enters. When it cannot retain any more, the moisture then begins to appear as condensation. 

In reality, the issue could have been there for quite some time but has only become apparent because the desiccant is no longer doing its job.

If you have condensation in double glazing then it is a sign that the sealant has failed and this usually means that it will have to be replaced or sealed. If the windows are dated then replacing the whole unit can be recommended so that the same problem does not occur again.


Have you heard about interstitial condensation?

Interstitial condensation creates structural damping that occurs when moist air penetrates inside the hidden space within an enclosed wall, roof or floor cavity structure. When that moisture laden air reaches a layer inside the interstitial structure that is at dew point temperature, it will condense into liquid water.

The moisture laden air can penetrate into hidden interstitial wall cavity from the exterior in warm outdoor temperatures and inside the building during cold outdoor temperatures.  The resulting structural damage, along with mould and bacteria growth may occur without any visible surface indications until significant damage or extensive mould and bacteria growth has occurred. 

Mould Removal

If you find a colony of toxic mould, it is very important that you do not disturb it. Touching or moving the mould can cause an enormous amount of harmful spores to be released in the air, to the detriment of you and the people you share your home with.

For other, more common strains of mould, there is a wide variety of mould treatments available that clean the mould, which are easy to use on your own.

A simple solution for removing non-toxic mould from your home is to clean it using a non-toxic, mould cleaning solution. When the mould has been eradicated, it is important to dry the surface thoroughly, in order to prevent the mould from returning.

Another simple yet short-term solution is to kill the mould and nasty marks on your walls with bleach. If you do wish to try this tactic remember to wear thick clothes (you don't mind getting ruined), rubber gloves and a face guard as both the mould and bleach fumes can be dangerous to inhale. To clean mould off your walls, follow these steps -

  • Simply mix one part bleach to four parts water.
  • Using a damp cloth gently scrub until the mould is gone.
  • Once finished, dry the area well with a soft cloth.

Remember however, this is not a long term solution and you really need to tackle the cause of the mould to ensure it doesn't come back.

The Cure to Condensation

The reason condensation appears in your property is due to a lack of adequate ventilation which causes humidity levels to rise. As we spend more time indoors and make our property more energy efficient the build up of moisture and humidity levels increase.

There are three basic ways to control the problem of condensation, by looking at relative humidity, ventilation and insulation:

  • Control humidity. Control the relative humidity in your home through the use of extractor fans in kitchens and bathrooms.
  • Provide ventilation - ensure there is adequate ventilation throughout the property. 
  • Add insulation.

In fact, four people living in a 3 bedroom property would create 112 pints of moisture a week from just breathing, cooking, showering and boiling the kettle.

So how can you reduce the condensation in your property?

So when the air is very warm, like after a hot shower, a lot of condensation will form on the cold coils. Of course the amount of condensation that forms is also proportional to the humidity in the air, so a humid bathroom creates the 'ideal' environment for a refrigerant dehumidifier to extract moisture, but does a dehumidifier really do enough?  

The usual top go-to suggestion for reducing condensation is to purchase a dehumidifier, they're easy to pick up and failry inexpensive. However, many are unaware of the several cons that are also associated with dehumidifiers. For example dehumidifiers blow out warm air from the back, which in the summer months can create an excessive and overbearing heat. Dehumidifiers also increase your energy costs meaning whilst they are cheap to purchase, can end up being a costly investment. 

If you constantly have to wipe condensation off your windows and have a dehumidifier running for lengthy periods of time (costing you money) then you may want to think about having a whole house ventilation system installed as a permanent solution to condensation and to improve the air quality indoors for your tenants or family. 

There are also several easy steps you can take to reduce moisture in the home and minimise the risk of condensation.

18 Tips To Reduce Condensation and Damp

1. Ensure Washing Machine Is Correctly Vented

If you have a washing machine or tumble dryer in your property, ensure that it is vented correctly. From just one load of washing two litres of water is emitted into the air, this effect is only magnified if the machine is fitted in a kitchen as cooking will only add to the condensation.   

2. Dry Clothes Outdoors

Where possible, try to dry your clothes outdoors to prevent excess moisture from building up in your property. If you are unable to dry your clothes outdoor then keep them in a bathroom with the door closed and windows open until the clothes are fully dry.

3. Close Kitchen & Bathroom Doors

Bathrooms and kitchens are the worst culprits for condensation. When cooking food, boiling the kettle or taking a shower, ensure that your kitchen or bathroom door is kept closed to prevent the moisture in the air from going into colder rooms which will cause condensation to form if it touches a cold surface.

4. Use Pan Lids When Cooking

When cooking ensure that you cover your pans with a lid to reduce moisture being created from the water boiling. Also, ensure you are using an extractor hood if you have one above the cooker or an extractor fan if you have one installed, these are designed to help reduce moisture created when cooking.

Remember, don’t turn off your extractor fan as soon as you finish cooking as the moisture can still be in the air even when you have finished, instead leave it on afterwards for 10-15 minutes to help to clear the humid air. Another option is to purchase an extractor fan with intelligent humidity sensors which speed up when you start boiling water and slow down once humidity levels have returned to normal.

5. Turn On Extractor Fan When Taking A Shower

Similar to when cooking in the kitchen, when you are taking a shower or having a bath ensure that you turn on your extractor fan to remove the steam and moisture that is created when running warm water in a cold environment. This will help reduce the amount of condensation that appears on your bathroom windows and walls.

6. Stop Using Portable Gas & Paraffin Heaters

Portable gas bottles and paraffin heaters produce a lot of moisture, along with a lot of toxic fumes. Not only is this form of heat causing excess condensation in your property, it is also a health and safety hazard which is stated in most tenancy agreements as not allowed in rented flats.

7. Cover Up Fish Tanks & Aquariums

Many families have house pets and plants which produce a lot of moisture. Make sure you cover up your aquarium or fish tanks to prevent excess moisture. If damp patches start to appear on your walls or you start to notice more surface condensation on your windows and walls near to your house plants then look to move them outdoors.

8. Wipe Down Cold Surfaces

If you don’t have an extractor fan in your bathroom or kitchen then make sure that you wipe down any cold surfaces when you have been cooking or taking a shower to remove any moisture that may have settled on the surface. This excess moisture in the air sits on the surface and will quickly turn to mould if left untreated.

9. Don't Overfill Wardrobes & Cupboards

Do not overfill your wardrobes or kitchen cupboards. A lack of ventilation and air moisture trapped in warm overfilled cupboards can become a breeding ground for mould as the air is not able to circulate freely inside. You might notice a musty smell or clothes might have a damp feeling to them which is a sure sign that the cupboard is overfilled.

10. Move Furniture Away From External Walls

For the same reason as above, make sure that your furniture is at least 50mm away from the surrounding walls so that air can circulate around the property. Try to ensure that your wardrobes are placed against internal walls in your bedroom which will be less cold than external walls and less likely to cause damp and mould problems.

11. Ensure Your Property Has Adequate Heating

Ensuring an adequate amount of heating in your property will improve the internal temperature of surfaces in the house and reduce the likelihood of condensation. Also, make sure your home is energy efficient by ensuring you have insulated walls and double glazed windows installed so the heat doesn't escape from the property.

12. Open Windows When Weather Outside Is Warmer

If you use a room on a regular basis, such as a living room and the weather is not cold outside, open a window slightly to improve the ventilation in the room. Breathing is a major cause of condensation so this will help to improve the ventilation in your property.

13. Install Double Glazing, Loft & Wall Insulation

Double glazing, loft insulation and draft proofing will help to reduce the amount of heat that is lost from a property. Installing insulation will help to keep the temperature of the surfaces inside your property at a higher level.

14. Install An Extractor Fan

Adequate ventilation is essential to allow the moisture to escape from a property before it turns into condensation. Installing an energy-efficient extractor fan in the kitchen and bathroom can improve the humidity levels and prevent condensation.

An alternative approach would be to have a whole house ventilation system installed in your home, ATMOS® can provide a condensation-free environment and can help reduce the moisture levels throughout your home.

Here are some additional tips that will help cure your condensation woes:

15. Check the windows

Over time the sealant around your windows may become damaged and start to allow rain to seep into your home. The water entering the property will cause an excess in the moisture levels resulting in condensation. This type of condensation is known as exterior condensation as it allows the moisture in from outside.   

16. Monitor the moisture

Condensation is the result of excess moisture and is something that can sneak up on us, by investing in a moisture meter you can keep track of these levels before it's too late.

17. Check the exterior for any damage

Have a good inspection of the exterior of your property, look for cracks and any damage that could be letting water in. Over time parts of your property deteriorate, so it's best to look into replacing window panes or the whole window or having the roof re-done. 

18. Use bath mats

Make sure you have a decent size bath mat for your bathroom to avoid saturating bathroom floors when getting a bath or shower. The bath mat should help soak up some of the moisture, helping to reduce the condensation in the room.  


The cure for condensation lies in preventing the condensation from ever occurring in the first place. If you are suffering from condensation problems then we may be able to help you. We have over 30 years experience in the industry and work across the whole of the UK to solve condensation and mould problems. We have local ventilation experts available, who can carry out a detailed survey and create a report which will tell you exactly what is causing the problem and how to rectify it.

If you are not sure if the problem is condensation or whether it could be rising damp or due to a leak from the roof or guttering then get in touch to arrange a free home survey and a local ventilation expert will contact you to arrange a suitable time to check whether the problem in your home is due to condensation.

To book your free home survey click here.