A Guide to Condensation and How to Reduce It

What is condensation?

Even though you can’t see it, the air in and around your home contains water vapour. The warmer the air, the more water it contains. When warm air comes into contact with cold surfaces such as outside walls, window panes, tiles or mirrors, the water vapour turns into droplets of water. This is condensation.

Every home will get condensation at some time. It’s formed from the moisture we produce as we cook, wash, dry clothes and go about our everyday lives. Even our breathing produces water vapour - that’s why bedroom windows can mist over on cold nights.

Where will you find condensation?

Condensation is surface dampness. It can build up on almost any cold surface within our homes but is most common on:

• the inside of windows
• external walls (especially those that face north)
• in the corners of rooms
• in or behind cupboards or wardrobes.

Why is it a problem?

If condensation builds up regularly, surfaces can stay damp for a long time. When this happens, mould can begin to grow on walls and ceilings, furniture, soft furnishings (such as cushions and curtains) and on clothing stored in wardrobes and drawers.

When the weather is warm, condensation is less of a problem because we’re more likely to have our doors and windows open, which allows excess moisture to escape. But when the weather gets colder, we tend to keep our windows and doors closed to keep the heat inside. That’s when condensation and mould can become a problem.

Did you know?
The breath of a sleeping adult will add about one-third of a litre (over half a pint) of water vapour into the air overnight.

What are the causes?

• Producing too much moisture in your home
• Not enough ventilation
• The temperature in your home is too low

Step 1 - Reduce the amount of moisture you produce

The first step in tackling the problem of condensation is to reduce the amount of moisture you produce in your home

When you’re cooking

• Don’t boil kettles or pans for longer than you have to, and make sure you put lids onto saucepans.
• Close the kitchen door to prevent steam from escaping into the rest of the house.
• Open a window or use an extractor fan if you have one. Leave the window open or the extractor fan switched on for 15 minutes after you’ve finished cooking to allow the steam to clear.
• Wipe away any condensation that forms on your windows or other surfaces. This will help to prevent the growth of mould.

When you’re drying clothes

• Avoid drying clothes indoors, especially on radiators. Hang clothes outside to dry, or use a tumble dryer instead, making sure it’s vented to the outside of your property.
• If it’s wet outdoors and you don’t have a tumble dryer, dry your washing in your bathroom. Ventilate the room by leaving a window open slightly and keep the door closed to prevent moisture escaping into the rest of the house.

When you take a bath or shower

• Reduce steam by part-filling your bath with cold water before topping it up with hot water.
• Close the bathroom door and ventilate the room by opening a window or using an extractor fan.

Step 2 - Improve the ventilation in your home

Keeping your home well-ventilated will reduce condensation by removing moist air from inside your home. Good ventilation is important, even when the weather is cold and we are understandably more reluctant to open our windows.

Ways to improve ventilation

• Don’t overfill cupboards or wardrobes, and don’t push furniture right up against the wall. Leave enough room for air to circulate.
• Make sure that you don’t block any air vents or airbricks in your property.
• Open a window or use an extractor fan when you’re cooking or taking a bath.
• Open the interior doors of your home from time to time to allow dry air to circulate (but remember to shut kitchen and bathroom doors when you’re cooking or washing).
• Keep a small window open slightly in the rooms that you’re using. If your windows are fitted with trickle vents, check these are open. A trickle vent is an opening in a window frame that provides a small amount of ventilation.

Keep your home secure

When you open a window to ventilate a room, make sure it doesn’t cause a security problem. Check that the window isn’t accessible from outside (such as from a garage or shed roof) and remember to close windows before you go out.

Step 3 - Keep your home well-heated

Ways to keep your home warm

Condensation is less likely to develop in a warm home. In cold weather, set your thermostat to provide a low background heat throughout the day, even if you’re not at home. This will warm up the whole building, not just the air inside the rooms. It means there will be less chance of warm, wet air coming into contact with cold walls and surfaces and causing condensation.

Good insulation and draught-proofing will cut your fuel bills and help to warm the temperature inside your home and the surface temperature of external walls. For advice on insulation, contact Origin Housing or your local council.

Don’t heat your home using bottled gas or paraffin heaters. They produce lots of moisture and are a health and safety risk. Most tenancy agreements do not permit the use of this type of heater. Check with Origin Housing if you’re unsure.

Remember, keeping your home warm will help you to solve the problem of condensation, but only when combined with Steps 1 and 2 in this booklet. For more information on the most efficient ways to heat your home, visit the Energy Saving Trust website at www.energysavingtrust.org.uk

De-humidifiers

Dehumidifiers are useful if you need to dry out a damp room that has been damaged by a leak, but they won’t deal with the main causes of condensation.
  

Getting rid of mould

Mould appears as sooty black speckles that cluster in dark damp patches on ceilings, walls, furniture, carpets, and even on your clothes. The mould and its spores carry the musty smell often associated with a damp house.

To kill and remove the mould, you’ll need to wipe down or spray mouldy walls and window frames using a fungicidal wash. You can buy these washes from most supermarkets, hardware stores or DIY shops. Choose a product that has a Health and Safety Executive (HSE) approval number. When you apply the wash, make sure you wear rubber gloves and follow the manufacturer’s instructions carefully.

If the mould has spread to your carpets, these should be shampooed. Don’t try to remove mould using a brush or vacuum cleaner as this could spread the mould spores around your home. If your clothes have been affected by the mould, they’ll need to be dry cleaned.

Once you’ve treated the mould and removed it, redecorate using fungicidal, mould-resistant paint. Or, if you’re wallpapering, use a paste that contains a fungicide. This will stop the mould from coming back.

Remember:

The only sure way to prevent condensation and the build up of mould is to follow the three essential steps outlined in this booklet. You must follow ALL three steps if you want to solve the problem of condensation. 

Let’s recap
  
STEP 1 Reduce the amount of moisture you produce
STEP 2 Improve the ventilation
STEP 3 Keep your home well heated

Still having problems?
  
Mould and damp are usually caused by condensation, but not always. If you’ve followed all of the steps in this booklet and you’re still having problems, the cause could be:
•    A leaking water pipe, waste pipe, or overflow.
•    Rain getting in through your roof because a tile or slate is missing.
•    Blocked guttering.
•    Rain seeping in around window frames.
•    Rising damp caused by a defective or missing damp proof course.
Rising damp can usually be identified by a ‘tide mark’ at the edge of the area of damp, often towards the bottom of an interior wall. Leaks (or penetrating damp) cause patches of damp to form on wallpaper or plaster, but only in the area around the leak.

If you think rising damp or a leak is causing a problem in your home, contact Origin Housing for advice and, if necessary, we will arrange for your property to be repaired.