CONDENSATION                                   condensation-window-words-edit

What is Condensation ?
Condensation is a relatively new phenomenon resulting mainly from changes in lifestyle and our desire to keep heating costs as low as possible.
Condensation is related to the way we heat, ventilate and insulate our homes. In Days gone by, most homes had  2 chimneys; allowing up to four air changes per hour. Doors and windows were generally less well fitting than they are today. This natural ventilation was the very process which prevented condensation!
To cope with increased fuel costs came the trend to insulate. This resulted in loft insulation, cavity wall insulation and DOUBLE glazing, that is good new wood or alluminium tight fitting doors.
However, it is also a fact that energy-efficient homes are more likely to suffer from condensation – because anything that keeps warm air in will also keep fresh air out, creating the ideal conditions for condensation to form.
Before we tackle the problem, we have to understand exactly what condensation is, then find the best way to deal with it.
Condensation is merely the air’s natural moisture content settling on cool surfaces, the amount of moisture in the air is called relative humidity. If the humidity level rises about 70%. mould and mildew (black corners) will be encouraged to grow.
Astonishingly, the average family creates up to 20 pints (11.36 Litres) of moisture every day, simply by washing, cooking and breathing.  This Moisture must go somewhere and be dealt with to avoid condensation.

Q- What is condensation ?
Condensation is water vapour suspended in air.
Q- Where does water vapour come from ?
The most common sources of water vapour are cooking, drying clothes on radiators or hangers, washing up, in house plants, moisture in newly built properties and extensions and from the breath we exhale and of course lots of hot showers.
Q- Where can condensation occur ?
Due to the thermal currents in the house, condensation can occur in a number of places, usually at cold spots i.e. An unheated room or a conservatory without any form of adequate heating.
Condensation forming on the room side surface of a sealed unit indicates a high water vapour content present and that the temperature of that room side glass surface is inadequate.

Statement – “I did not have condensation before my new windows were installed. There must be something wrong with them.”
This is a common assumption but, unfortunately, it is also incorrect. Windows cannot and will not produce any water. This “water” is produced by our normal living activities. Therefore we, the householder have created the problem.
Q- How do I know if I have condensation ?
Condensation will take many forms, the most common being steaming windows and puddles of water on the window sills. In extreme cases, dark spots of mould will appear around the windows, wall coverings and mastic seals throughout the house.
If you have a non-condensing tumble dryer, make sure it is properly vented to the outside of your home.
Remember, tumble dryers can create upto 16 pints of water vapour during one cycle.
Q- How Can double glazing help ?
Sealed unit replacement windows act as an insulator which will reduce heat loss which under normal circumstances, would be conducted from the inside of the room to the outside. Please remember that sealed units act as an insulator and are not a source of heat, therefore all rooms should be adequately heated – especially conservatories. The likelihood of condensation forming on a warm surface is therefore reduced.
Q- How do I reduce condensation ?
Condensation can be controlled by providing natural ventilation to change air on a regular basis and by maintaining an even temperature. This is achieved through ventilating units which are controlled by humidistat’s, an airbrick, or by opening windows more often.  Please remember that the airbrick must be open to achieve good results. An effective way of controlling condensation would be to install a dehumidifier.  This cost could be avoided if the problem is one of ventilation, by installing an airbrick thereby creating ventilation or controlling those causes of moisture, that result in a build up of moisture in the air. Another solution is 2 air vents directly above a cooking surface with a small window that is allways open.
Two sleeping adults can exude upto around two pints (1.14 litres) of moisture in 8 hours, which is absorbed as water vapour into the atmosphere.
New Property:
The airbricks, timber, concrete and other materials in an average 3 bedroom house absorb 1500 gallons (6819 Litres) of water. The same principle will apply to a conservatory base and the construction materials used. As with any new building work, please allow a period of drying out to ensure problems are not encountered in the future.

Double Glazing – Cannot Cause Condensation:
By acting as a heat barrier and providing an inner pane which is considerably warmer than the outer pane, the likelihood of condensation forming is reduced.
Condensation is the result of a build up of moisture caused by our normal lifestyle and the continual improvement and modernisation of our homes.
Replacement windows cannot produce condensation. Double Glazing will act as an insulator if there is sufficient heat within the house in the beginning. Therefore it is wise to attempt to control the amount of water vapour displaced within the household and to provide controlled ventilation to dispel this moisture before a problem arises.
Kitchens & Bathrooms:
Prevent water vapour finding its way into the other rooms of your house by closing the adjoining doors and leaving a window open after cooking and showering to allow a change of air. Extractor fans and cooker hoods work well for this purpose.
If you find dark mould spots forming, treat the affected areas immediately with a solution of household bleach.  This will kill the mould spores and prevent them from spreading to other areas. All new houses with improved insulation and replacement windows are likely to trap moisture build-up. This can be identified and dealt with, as long as all the rooms are heated throughout the house, and the air changed on a daily regular basis.
Remember – Prevention is better than Cure !

New Homes versus Older Homes..
You might nave noticed that newer homes have more condensation on their windows than older homes experience. This is because we have learned to make new homes more energy efficient, keeping the warm air inside, which makes the temperature difference on the windows greater, causing condensation. Older homes are more prone to drafts, letting the warm air into the outdoors, which makes for a less drastic temperature difference and therefore less condensation on the windows.
This is a tenant’s problem and has to be dealt with, (it is not the home or the owner of the home’s cause)
©2008 Royal Institution of Chartered Surveyors (RICS)
“Condensation is often considered as one of the most widely misunderstood causes of ill health and defects in residential properties. It is also often confused with other defects such as penetrating and rising dampness”
More information
-When is Condensation a problem?  …If the room is completely black.
-How can you tell it’s condensation?  …On touching it with a finger, there is black powder.
-What can you do about it?   ….Our agency can provide someone to clean it and paint over.

When is it a problem?
Every home gets condensation at some time – usually when lots of moisture and steam are being produced – for example, at bath times, when a main meal is being cooked or when clothes are being washed.

It is quite normal to find your bedroom windows misted up in the morning after a cold night. There is nothing much you can do to stop this.

However, if your home never seems to be free from condensation, read on.
How can you tell it’s condensation?
Condensation is surface dampness. It mainly occurs on cold walls indoors and other cold surfaces such as tiles and cold water supply pipes under sinks and hand basins.

Condensation is usually at its worst during the winter. It often results in black mould growing on walls and other surfaces, a test is; you wipe it and it will be black dust on your finger.
What can you do about it?
The four main ways to deal with condensation are:
1) Produce less water vapour or steam in your home.
2) Don’t let the water vapour and steam that is produced spread all round the house.
3) Keep your home daily ventilated
4) Keep your home warm.
To deal with a condensation problem effectively, you will probably need to do all four, though the first three are the most important and can be done at no cost.

1) Produce less water vapour

The amount of condensation depends on how much water vapour is in the air.

Many everyday activities add to the water vapour level in your home, but their effect can be kept to a minimum.

⦁ Cover pans when you’re cooking.
⦁ Don’t leave kettles and pans boiling longer than necessary.

Drying clothes
⦁ Hang washing outside to dry whenever you can.
⦁ If you have to use a tumble dryer make sure it’s vented to the outside.
⦁ If you have to dry washing indoors use the bathroom and keep the door shut and the room well ventilated.
Do not hang wet washing on radiators all round your home – doing so is very likely to cause condensation problems.

Keep the bathroom well ventilated, if there are no windows, keep the door open and keep another room’s window open.
2) Keep your home ventilated
⦁ Let wet air out
⦁ The best way to remove water vapour is by providing adequate ventilation. Nobody likes draughts, but some ventilation is vital.
⦁ Keep a small window ajar, or a trickle ventilator open, in each occupied room to give background ventilation, (but make sure your home is still secure).
⦁ Open the windows to let the water vapour out, especially when you’re doing the washing or cooking.
⦁ Windows near the ceiling are more effective at letting water vapour out than ones lower down.

The best approach to heating in order to reduce condensation, assuming you have taken the other three steps, is to heat your home at a low level for a long time.

Keep the heating on, but set it to provide just a minimum of background heating. This will warm the whole building up and keep it warm, so there are no cold surfaces.


Installing a de-humidifier may not be the best way of tackling condensation. They are expensive to buy and must be emptied every day. However, they are useful for drying damp buildings out, for example after leak damage, or for specific rooms.

De-humidifiers are only the second substitute for the vital, no-cost measures of reducing the amount of water vapour put into the air and keeping rooms well ventilated.

Dealing with mould growth
The best way of tackling mould is to reduce the condensation levels and prevent it growing in the first place.

Dampness from condensation often causes the growth of black mould on walls and other cold surfaces such as tiles. Mould and mildew can also grow on furnishings, curtains and even clothes in wardrobes. It may first appear in corners or behind cupboards, but it can spread across entire walls.

Mould can spoil wallpaper and furnishings and can make your home unhealthy.

Mould on washable surfaces can be removed by wiping down with detergents or proprietary mould removers. It can be washed out of fabrics, but may leave stains or spoil colours. Scrubbing with bleach is a good solution.

Last very important note;  the photo below reveals condensation in the TOP corners of a room, this is the tenant’s duty to clean and repaint.    When the condensation or water marks appear at the BOTTOM corners of the room, this will be the landlord’s duty and cost and not the tenant’s.