Condensation on walls is a common issue, especially in the UK. If you've ever rented, you will likely have had discussions with your landlord about reducing condensation. And if you own a home, you might be even more vigilant about looking out for signs of condensation forming. But what exactly is condensation and what causes it? What are the best methods to reduce condensation? Read on for everything you need to know.
Water can be in three different states: ice, liquid water, and water vapour. We shouldn't need to worry about ice in the home but the movement between water droplets and water vapour is key to the issue of condensation.
You can think of condensation as the opposite of evaporation. When water heats up, it turns into water vapour and evaporates into the air.
Condensation is the same process but the other way around. When warm air containing water vapour cools down and reaches its dew point, the water vapour forms water droplets. This is why you will see dew on grass first thing in the morning.
Condensation is most obvious when warm moist air hits a cold surface. You will see water droplets on cold cans of drink, for example.
Condensation on walls is due to this same process. Warm air inside the home hits a cold wall and the water vapour forms water droplets.
So condensation is formed when water vapour in moist air hits cold surfaces and forms water droplets. When we take this process and look at how we live in our houses, it becomes clear quite quickly what might be causing condensation problems.
There are two routes to condensation problems. The first is excess moisture in the air. The more water vapour there is, the more water will be left on the surfaces of your house when it cools down.
The second is ventilation. Adequate ventilation will allow damp air to leave the property efficiently. This will mean that the air in the home is less humid, reducing the amount of water on your walls.
Check out: What Causes Condensation On Windows
When you stop and think about it, you realise just how many of our day-to-day behaviours create moisture. Every time you boil a kettle to make a cup of tea, water vapour is released. The same happens every time you cook a meal or have a bath or shower. If you dry clothes indoors, this will also release water vapour, as well doing the dishes.
Most homes are equipped with ventilation. This can be things like extractor fans, trickle vents, a PIV system, or mechanical ventilation. If there isn't enough ventilation, then the moist air will have less chance of escaping your home before the vapour forms water.
If you notice condensation on internal walls, alarm bells should be ringing. Yes, a little bit of water never hurts anybody. But it isn't the visible water droplets that are the problem. It's what can happen when the water is left to build up over a long period.
If a condensation problem is left for too long, it will lead to damp walls, mildew, and mould growth. This combination can cause health problems for the people living in the home.
These include:
These health problems are more likely for vulnerable people, including babies and small children, the elderly, and people with pre-existing health conditions.
Damp and condensation don't just cause problems for the people living in the home, they can also damage the property itself.
Water seeping into external walls, ceilings, and other elements of the house can start to corrode the construction materials. Mould growth can also worm its way through, causing structural damage.
If the damp gets so bad that it starts affecting the structure of the building, then extensive repair work may need to be completed.
Condensation occurs in every home at some point and you may not be able to stop condensation altogether. What you can do, however, is reduce the amount of moisture present in the air. While at the same time working to increase ventilation.
This two-pronged approach means that you can reduce condensation to as close to zero as possible. By preventing water vapour in the first place as well as efficiently removing damp air quickly, there won't be time for much condensation to form.
Dig Deeper: How To Get Rid Of Condensation In Your Property
The more moisture in the air, the more condensation you will have. And there are some quick and easy steps you can take to reduce moisture.
When you are cooking, make sure to use pan lids as much as you can, and always turn the extractor fans on. This will reduce the water that escapes into the air. Try not to boil the kettle more than you need to.
Close the door to the kitchen when you are cooking to stop water from getting into the entire house and keep the windows open if you can.
Turn the extractor fans on and leave them on for 30 minutes after you have finished bathing or showering. Opening windows as soon as you are done can also help. Shut the door while you are bathing and keep it shut for 30 minutes afterwards.
Drying clothes indoors is pretty contentious. Everyone knows that it causes a problem with condensation but it is sometimes difficult to avoid. And it makes sense. For moisture to leave the clothes and make them dry, it has to go somewhere. And when you dry your clothes inside, the only place it can go is into the air.
In the summer, you may be lucky enough to have access to an outdoor clothesline. But if it's winter or you don't have an outside space, then the situation is more difficult.
A tumble dryer is a good solution, especially if you have a vented one. A vented tumble dryer will have a pipe that exits through an external wall and will pump the moisture out through there.
For many of us, however, a condenser tumble dryer is the only available option. These dryers remove moisture by moving hot air into a separate condensing chamber where it will turn into water that can then be removed.
A vented tumble dryer is less likely to create condensation because the warm humid air is actively being pumped out.
However, both types of tumble dryers will create heat. This heat will warm up the air in the room, which can then form condensation when it hits a cooler surface.
Ensuring that the room your tumble dryer is in is big enough and keeping the windows open while it is running can help.
If you don't have a dryer and you need to dry clothes inside, choose a room that can be well-ventilated. Make sure that the windows are kept open and the door shut. If you have a fan, this can help to keep the air moving while the clothes dry.
The other side of the coin of preventing condensation is increasing ventilation. Better ventilation means that moisture-laden air is removed from the building before it has the chance to form condensation.
Make sure that your extractor fans are working properly. Their blades can get clogged up with dirt and debris which can mean they aren't working as efficiently as they should.
Dehumidifiers can prevent condensation from forming. They work by drawing in moist air and then moving it over a refrigeration coil. This coil cools the air, which causes condensation to form inside the unit. The water is then collected in a tank which you can empty.
It may not be viable to have dehumidifiers throughout your home, but they can be placed in areas where there is persistent condensation or where moisture is most likely.
Because modern houses are designed to be more airtight and energy efficient, there is less opportunity for humid air to escape before it condenses.
In older homes, the walls themselves were designed to be breathable but modern building materials and a greater focus on insulation and heat retention means this is no longer the case.
A trickle vent is a solution to this problem. It is a background ventilator that is installed in window and door frames and it consists of a small, staggered slit that creates an opening for air to escape.
While they can be closed, trickle vents are designed to be left open at all times, providing an extra level of background ventilation to stop condensation from forming.
The relationship between insulation and damp is a complicated one. In some cases, insulation can work wonders for reducing condensation. In other cases, insulation can make the condensation worse.
Cavity wall insulation will trap heat in your home. This means that the internal temperature will be higher. If the insulation is done well and there aren't any gaps, this means that the walls themselves will also be warm. This will stop condensation from forming.
If, however, there are gaps in the insulation, this can cause a problem. These gaps will mean that the internal walls will be colder in some spots. In these cold spots, air condenses, leading to damp walls. Because, overall, the insulation has made the property warmer, there will be more condensation than there normally would be.
It can be possible to pinpoint the gap by figuring out where the wall feels cold. You can then apply anti-condensation paint to this spot on the internal wall. This paint adds an extra layer of insulation to the wall, keeping it warm and preventing condensation from forming.
One method of treating condensation through improved ventilation is a positive input ventilation (PIV) system. With a PIV system, a filtration unit is placed in the loft space (or on a wall if a loft isn't accessible). This unit actively draws in fresh air from the outside.
On the ceiling beneath is a distribution diffuser. Through this, the fresh air is pumped into the rest of the house. This constant pumping of fresh air creates positive pressure that forces the stale humid air in the home out through vents and other naturally occurring holes to the outside.
Because humid air is constantly being replaced by dry, fresh air, there is much less chance for condensation to form.
Unlike a mechanical ventilation system, a PIV system doesn't require extensive renovations, so it works well as a retrofit in a home that is already dealing with condensation.
Find out more: What Is A PIV Unit
Once you have implemented measures to reduce condensation through lifestyle changes and improved ventilation, you can tackle the damp walls themselves.
Discover: What Causes Damp Patches On Ceilings
Condensation isn't the only thing that can cause wet walls. There could be something more serious going on, such as rising damp or penetrating damp. Both of these will require the help of a professional to diagnose the problem and fix it.
This is when there is damage to the external walls or roof of your home, letting rainwater in. There could be broken guttering, missing roof tiles, or a crack in the wall. Anything that creates a hole where there shouldn't be can allow moisture and damp to set in.
A sign that you are dealing with penetrating damp rather than condensation is when you can see damp patches on external walls as well as internal.
This is when moisture from the ground rises through the walls of a building. Rising damp indicates that the property's damp-proof course has failed.
A common sign of rising damp is horizontal tidemarks on walls as well as rotting and damaged skirting boards.
If the condensation has triggered mould growth then you will need to remove it before you redecorate. It is a common misconception that bleach spray kills mould, but it doesn't. Bleach will just hide the mould while it continues to grow and the water in the spray could even cause more mould.
A specialist mould killer spray will work. You just need to spray it on and wipe it off with a kitchen towel. Remember to always wear a mask because mould spores will be released into the air.
Uncover more: How To Get Rid Of Mould Permanently
If the condensation or damp has left stains on your wall, then you will need to redecorate. Before you can do so, however, you need to make sure that the wall is prepared.
If you have bubbling or peeling paint due to the excess moisture, you can use sandpaper to sand it away and create a smooth surface.
If the wallpaper has been stained or has started to sag, then you will need to remove it.
Before you can redecorate, make sure the wall is completely dry. You can use a fan and a dehumidifier to speed up the process. Keeping the room well-ventilated by having the windows open will also help.
A stain blocker will seal in the stain and prevent it from bleeding through once you redecorate.
Once these steps are completed, you can redecorate the wall however you please.
Condensation is a common problem. It occurs when warm air that contains water vapour hits a cold surface. This creates water droplets which are absorbed into the wall and can spread. Eventually, you may be left with a damp problem that could cause damage to the house and its occupants. Tackling condensation can be relatively straightforward. If you reduce the relative humidity and improve ventilation, condensation is much less likely.
A positive input ventilation (PIV) system can improve ventilation and reduce condensation. If you think this option would be right for you, don't hesitate to contact us at PIV Team. Our expert team will work with you to install a PIV system that helps to keep your home condensation-free and healthier to live in.
