I have been asked this question many times (How to Reduce Condensation in my home). Condensation appears when air that is saturated with moisture meets a cold surface. Let's assume you reading this post because you have condensation running down your windows at home. Or you have noticed a slight discoloration on the ceiling. In this post, we will look at how condensation is formed in the home. Thereafter we will look at ways to prevent condensation in the home. It seems many homeowners in the Cape, in particular, have a problem with condensation. This, however, is our long cold and very damp winters. Warmer homes have fewer condensation problems than cold homes.

As winter arrives it brings our attention to the damp and condensation problems that are lurking in our homes. This is probably one of the most common types of dampness in your Home. In fact, this will cause wallpaper to lift. Damp patches to appear on walls and a build-up of moisture on your windows as well as your ceiling.

If this condensation is not treated it will lead to mold growth which can be potentially harmful. This can lead to health issues and breathing difficulties.

The reality is that four people living in an average size home can create as much as 8 Liters a day of condensation in your home. Condensation is also caused by bathing boiling a kettle as well as cooking.

moisture causing condensationWhat is Condensation and How Does it Form?

Lets first define what Condensation is and what causes it. Water in the air settles on much colder surfaces like windows walls and ceiling and make them wet. Very much like a glass filled with cold water sweating on the outside.

If moisture is left unattended this will eventually effect paintwork wallpaper as well as ceilings.

Metal windows, as well as older wooden windows, are well known for assisting in creating more condensation in the home.

Dampness also encourages the growth of mold spores which thrive in these moist areas. This mostly leads to black sooty mold on windows, and you might also notice mold on walls. Even on curtains, where cold has been allowed to build up over time. This will also have a strong odor.

All air contains water vapor the amount of water that the air carries is affected by the temperature of the air. This is Called Relative Humidity.

Hot air carries more moisture than cold air. This means as the air rises it is able to carry a higher volume of water.

Once the air is saturated with water vapor (at any given temperature) it will deposit beads of water (condensation). On any surface that is cold enough. The temperature of the surface at which this moisture will form is called the ‘dew point’.  (For an example, take a cold glass bottle out of the fridge. The glass will immediately sweat on the outside.

what-causes-condensationCauses Of Condensation In The Home

One of the biggest factors causing Condensation is the DEW point in the home. Colder homes will have a low DEW point. This means condensation forms far easier. Warmer insulated homes will have a higher DEW point as the home is between 4-8 degrees warmer in winter.Therefore increasing the DEW point and reducing condensation.

In fact, cold homes are a natural starting point when it comes to condensation. Uninsulated homes are far colder inside than insulated homes. The fact is as much as 4-8 degrees warmer in winter and cooler in summer. This warmer temperature in the home increases the DEW point. How this works is the airborne moisture in the air makes contact with a cold surface and forms condensation.

An insulated home as stated earlier improves indoor temperature by 4-8 degrees as mentioned earlier. Therefore the home is warmer and the DEW point for warm airborne moisture is increased. Thereby reducing the ability of the airborne moist air from condensation.

Some of the biggest culprits in causing Condensation are Cooking and bathing or showering. In fact, another culprit that causes condensation is wet clothes on a drying rack. As a result of these factors, the moisture gets into the air and attaches itself to windows wall or ceiling.

what-causes-condensationReduce Condensation in your home?

An insulated home will reduce the cold in the home. A well-insulated home will retain heat much longer than an uninsulated home. So heating throughout the home should reduce condensation in most homes. If the air in the home is freezing remember that if the dew point is low you will have condensation in the home. When there is cold air that meets warm air from breathing or bathing or cooking. If the air is warmer then there is less of a problem.

Remove condensation from wall and windows. One of the best options for removing the moisture from walls and windows is a small battery powered vacuum made by Karcher specifically for windows and walls. These portable vacuums have a small tank on the back. Therefore once the moisture on walls and windows is removed the water can be tipped out into the basin. Thereby leaving no moisture in the bathroom.

An alternative method is to buy a small squeegee from your local hardware. This, in fact, works very well. Remember by removing all the moisture from the windows in the home will reduce the cycle of the moisture drying in the day.

 Do not pack too much clothing etc into bedroom wardrobes etc as this will help mold growth in these areas. If there is no space for airflow then the clothes etc will become moldy.

Make sure your home has enough heating as a warmer home will reduce condensation.

 Insulating the roof space with Roof Insulation and fitting Double glazed windows will make the room warmer and this, in turn, will reduce the condensation.

 Make sure your home can breathe check all vents and extractor fans and roof extractor whirly birds are a great help in certain applications.

drying wet clothes in the home causes condensationDrying Wet Clothes In The Home Causes Condensation

In cases where wet clothes are hanging on a dryer rather take the option of putting these in a tumble dryer. Alternatively, take the wet washing to be dried at your local laundry. Never dry washing inside the home in winter.

What can we do then to dry clothes? Rather move the clothes dryer to the garage or an outside room. When using a washing machine be sure to make sure the washing machine can be vented out of the home rather than in the home. In fact, if possible move the washing machine out of the home into a garage or laundry room if you have one.

Firstly warm air in the home meats water and this becomes airborne water. How did this start? Clothes or towels are wet and are maybe getting hung near a heater or over a heater to dry. As these clothes dry the moisture is released into the room.

Secondly, airborne water and cold surfaces like windows ceilings and walls will then form condensation. As the clothes are dried the moisture is removed from the clothes. Clothes being dried over a heater will cause airborne moisture. When this airborne moisture makes contact with any cold surface it reaches DEW POINT.

This causes a cycle were walls ceiling and windows will end up with condensation. Take a glass of cold fridge water and watch how the glass sweats on the outside. The fact is the cold glass meets the warm exterior and forms condensation on the outside of the glass.

reduce-condensation-when-cookingReduce Condensation When Cooking

Cooking as we know is another major contributor to condensation and mold. Therefore wherever possible make sure to keep the lids on the pots while cooking. This will reduce cooking time as well as save up to 25% on electricity.

As a matter of fact, if your stove has an extractor make sure to use this. And be sure to set the extractor on max to reduce the condensation especially on wet cold days. When cooking in the kitchen it is very important to open a window.

When boiling water in a kettle be sure to stop the kettle just before the water has boiled. Thereafter Immediately put cold water into the kettle to stop the kettle steaming. This simple act reduces the amount of steam when stopping just before boiling and by pouring cold water steam is canceled with immediate effect.

This will allow moisture to escape therefore reducing the potential for the condensation. In fact, if your kitchen is not open plan and there is a door from kitchen to the rest of the home close this door. This will reduce the potential for the condensation to shift to other areas of the home. However be careful opening windows on cold rainy days as the outside air on these days will be full of airborne water.

To avoid mold growth one would have to wipe down the walls and ceiling regularly and use a dehumidifier. The best option is to get rid of the problem rather than try and make a plan to get through winter after winter.

reduce condensation in bathroomsReduce Condensation in Bathrooms

Bathrooms as we well know are major contributors of condensation in the home. In order to reduce the condensation in the bathroom area, there are a few simple steps.

Firstly install an extractor. However, it is far more effective if the extractor takes the air out of the bathroom through an extractor on the window or wall. This is a better alternative to releasing this moisture into the roof space. Releasing moisture into the roof space can affect other areas of the home.

Most importantly wen selecting an extraction fan for your bathroom, be sure to select a good quality extractor that has a high volume intake. In addition, try and have your extractor set to switch of a few minutes after your shower or bath.

In this manner, you ensure that almost all the moisture is removed. Also, open the window in the bathroom to allow more moisture out. However, if you feel the temperature outside is too cold to dry clothes naturally do not open the window. The reason for this is that you will be inviting more cold air with moisture into the home.

Finally when painting the walls and ceiling of the bathroom make sure to use an eggshell based paint or a paint that is specifically made for bathrooms. In fact, this will prevent moisture in the air sinking into the walls. This, in fact, will start leaving unsightly marks on the walls and ceilings. The end result would then be mold on walls and ceilings.

how to treat condensation on walls and windowsHow to Treat Condensation on the Walls and Windows

Condensation on the windows should rather not be wiped with a cloth or towel. Especially if these will be left in the bathroom or the home. As they will cause more condensation a with the cold air.

Rather remove the cloth after removing the moisture on the windows from the home. One of the best options for removing the moisture from walls and windows is a small battery powered vacuum made by Karcher specifically for windows and walls.

These portable vacuums have a small tank on the back. Therefore once the moisture on walls and windows is removed the water can be tipped out into the basin. Thereby leaving no moisture in the bathroom.

An alternative method is to buy a small squeegee from your local hardware. This, in fact, works very well. Remember by removing all the moisture from the windows in the home will reduce the cycle of the moisture drying in the day.

dehumidifierA Dehumidifier A Good Way How To Reduce Condensation

In fact, a great option for reducing moisture or condensation in your home is also to buy a small dehumidifier. A small dehumidifier can remove as much as 12 liters of water a day.

This, in fact, is great and the added benefit is the dehumidifier be removing the moisture leaves the walls and ceiling warmer.

As a result of condensation where would you find mold or black mold. Firstly the ceiling above is especially in the corners near or on the cornices. Secondly, lower down the wall near the skirting. Also around window frames.

Other Areas Contributing to Condensation

Window condensation – Beads of water on windows

Pools of Water on the windowsill

Beads of water on external walls

Patches of damp showing on external walls

 Damp patches on ceilings

 Another area is damp patches in the corners of rooms

Damp internal walls

Black mold on window frames, window recesses, and windowsills

This black mold in cupboards is easily visible

Black mold on curtains and clothes

Wet internal walls

In fact, black mold on carpets – can be a symptom  but is more often a sign of penetrating damp especially if you don’t have any of the symptoms above

Black mold on walls – particularly corners and recesses with little air flow

Diagnosing Condensation

Is it rising damp or condensation? Let us look at the rising damp myth, which is that all damp at low level must be rising damp. Let us be clear here, it is rarely rising damp. It is usually condensation although it can also be penetrating damp.  Where water is getting in through damaged or shoddily built areas such as through a roof leak. Cracks render failed wall ties and damaged brickwork or badly fitted window frames. Rising damp may occur in certain circumstances but it is very rare in modern housing.

questions and answers about condensationImportant Condensation Questions and Answers


Question – “I have black mold on my external walls and not on the internal walls in the same room, so it must be coming in from outside”

Answer – The interior surface of external walls tends to be the coolest surface in the room, so they naturally attract condensation.

Question – “My walls are wet, not damp or moldy, so it can’t possibly be just condensation”

Answer – Yes it can! There is no such thing as ‘just condensation’. It can be a cause of major structural damage as well as damaging paintwork, soft furnishings, and clothes if allowed to carry on unchecked.

Question: We have a three bedroom home and ever since we changed the metal window frames for new PVC double glazed window frames. We have a substantial amount of condensation in the home. Some rooms far more than others. We have no condensation in our bedroom were we have heating but in other parts of the home like our lounge etc, there is condensation.

Answer: Warm moist air meets surfaces that are cooler than its dew point temperature. The problem with heating some rooms and not others is that the warm air in the heated rooms will absorb water vapor. And then migrate throughout the house. When it meets the cold glass of your bedroom windows, the air becomes unable to hold so much moisture, which condenses.

The best option is to make the home warm enough and increase the dew point.

Refer to Insulation products that will give you the right R-value products like The Isotherm 145mm thick and the Aerolite 135mm thick are ideal to use and remember to use a fireplace or heater as well.