How to stop condensation

Condensation is the easiest damp problem to fix. It can often be solved cheaply and quickly, without the need for professional help. 

Read on to find out what causes condensation, how to get rid of it – in both the long and short term – and what to do if you have a serious condensation problem. 

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What causes condensation?

Condensation is caused when humid air meets cold surfaces like walls and windows.  

• When the temperature goes down, the amount of moisture that the air can hold falls and the tiny drops of water form on the surface.
• The amount of moisture in the air is increased by the release of water vapour from cooking, bathing and showering, and even respiration. 
• If condensation is allowed to sit on walls for long periods of time, it can penetrate the outer layers of your walls and seep into furniture where it becomes a longer-term problem, causing mould to grow.

Dehumidifiers are an affordable and portable aid to reducing condensation; our research into the best dehumidifiers can help you buy the most helpful model.

How to stop condensation

There are four things you need to think about when stopping condensation in your home:

1. Clearing existing condensation
2. Improving your ventilation
3. Upgrading your insulation
4. Making sure your heating is set up sufficiently

Fixing condensation: clearing existing condensation

In the short term, make sure you clear your windows of condensation regularly so it doesn't cause damage or develop into mould. You can do this easily with a towel, tissues, a squeegee or window vac.

When you can, always try to limit the amount of condensation produced in your home. Try to dry clothes outside rather than on radiators on sunny days and, if you don't have an extractor fan, open windows when cooking, washing up or showering. Find out more about how to improve your indoor air quality at home. 

A window vac is an easy way to remove condensation from your home, so we put bestsellers from brands like Karcher, Beldray and Salter to the test to find the best window vacs.

Fixing condensation: improve ventilation

Better ventilation helps reduce condensation problems. This can be as simple as remembering to open windows when you're at home or, if you have windows that lock when partly open, leaving them like this more often will help.

For a more permanent solution, ventilation options include:

• Building air bricks (made with small holes) into outside walls 
• Installing air vents through internal walls or sealed chimneys to allow airflow through the house
• Fitting roof ventilation tiles and/or ventilated soffits (under the roof and guttering) to allow air through the loft
• Adding window vents to the tops of window frames.

Bear in mind that these measures may mean that some heat is lost from your house, so balance that against your damp issue. You may want to consult a specialist to check the best course of action.

Make use of extractor fans, cooker hoods and dehumidifiers

Your bathrooms and kitchen are responsible for most of the moisture in your home. If you don't have an extractor fan in your bathroom, you should consider having one installed and making use of it each time you shower or bathe. 

In the kitchen, a good cooker hood can be an effective way of reducing a build-up of condensation while cooking. Extraction hoods, which send air outside through ducting, are generally most effective at removing steam and moisture. The best will work quickly and quietly to eliminate moisture and odours, while stopping grease from forming on your kitchen surfaces. Check out our guide to the best cooker hoods to find out more.

If extractor fans aren't cutting it, the next thing to consider is a dehumidifier, which will draw moisture out of the air. These can be particularly useful if you often dry clothes inside the house – another common source of excess humidity. There are different types and brands available, so read up on how to buy the best dehumidifier to find one that does the job.

We've heard from lots of Which? members who have successfully tackled condensation themselves by ventilating. One said: 'I open windows for better ventilation and use a dehumidifier to reduce water content in the air.'

Keen to get an extractor fan in a condensation-prone room? Use Which? Trusted Traders to find a local qualified electrician vetted by Which?

Whole house ventilation

For more serious condensation problems, there are bigger systems available that claim to improve ventilation.

We spoke to EnviroVent, a Which? Trusted Trader that specialises in whole house ventilation systems and extractor fans for bathrooms and kitchens. EnviroVent recommend a system called Positive Input Ventilation. It draws fresh air from outside a building in and then distributes it into all rooms through a centralised system that is usually mounted in the loft. 

'A conventional extractor fan that you might find in a bathroom or kitchen is an effective way of removing humid air from a building to reduce the condensation that causes damp; however, an extractor fan simply removes air,' says an EnviroVent spokesperson. 

'A Positive Input Ventilation System (PIV) closes the loop of airflow by controlling and filtering the air that is drawn into the building to replace the humid air that is removed by the extractor fan. A Positive Input Ventilation is a whole house ventilation system that improves air quality in all rooms.'

Alongside keeping your house free from condensation, follow our tips on how to get rid of mould.

Fixing condensation: heating and insulation

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Sudden rises and drops in air temperature can exacerbate a condensation problem, as water evaporates and condenses each time your central heating switches on and off. 

You may find that having your heating on a constant low heat is better for damp (and for your air temperature) than having it frequently swing between hot and cold.

If you're going to do this, make sure you're on the best energy deal first. Use our free, independent energy comparison service to compare gas and electricity prices and find the best provider for you.

Cold spots on walls or ceilings increase the likelihood of condensation, so better, more consistent insulation can be a good solution. Cavity wall and loft insulation, or having specialist insulation materials fixed to the outside of your house can all help. 

For information about improving your insulation, see our expert guides on loft insulation costs and savings and cavity wall insulation costs and savings. 

Keep in mind that in some circumstances cavity wall insulation can be the cause of damp, but this tends to be rare. See our advice on penetrating damp for more details.

If you have single-glazed windows, this may also be part of the problem. Single-glazed windows are a lot colder inside than double-glazed ones, so are likely to attract condensation. Our guide to the best double-glazing companies rates big brands and independent traders. Check out our double-glazing costs guide, too. 

If you do decide to install more insulation or double-glazed windows, this should be balanced with good ventilation in your home (as mentioned above), or all the extra energy-saving measures could cause damp problems to re-occur. 

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