This project is presented by Property Repair Systems
Summary: This project covers the causes and treatment of condensation.
If you need any help with any type of condensation problem etc.... Property Repair Systems will be pleased to give you completely free, no obligation advice on 01626 331351 or email help@propertyrepairsystems.co.uk. The information you need may be in the project below. If not, call them. They are experts in all matters relating to Condensation and damp in buildings and offer quality products at competitive prices, with full support for both the trade and DIY customers.
All air contains water vapour. The quantity contained depends on the temperature of the air. This ratio is called the ‘relative humidity’. Hot air is able to carry much more moisture than cold air, so as the temperature of air increases it is able to hold a greater volume of water. The water comes from our breathing, bathing, cooking and other domestic activities.
At any temperature, when the air becomes saturated, it will deposit beads of water (condensation) onto 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 glass bottle out of the fridge).
If this happens near the ground, to a small layer of air, dew or frost will be formed, if a larger amount of air is involved, mist or fog will arise. If this happens to air that is rising in the atmosphere and expanding. Clouds will form
If it happens in the home....It's called condensation.
As soon as warm air, containing vapour, hits a cooler surface, it will condense. This is most obvious on windows and wall tiles, but it is happening on the walls and ceilings a lot of the time. If we insulate ourselves and warm the house thoroughly, then this should not happen I hear you cry..... But it will! The air temperature will rise until it finds a cooler surface, unless we let that air out and some cooler air in.
In respect to this a change of air is recommended in all rooms in the house, at the very least, once a day.
The affore mentioned can aid in resolving damp and mould issues but for a total solution the problem has to be delt with on a more complete level. View the steps below to cover all eventualities:
Condensation is most obvious on mirrors, single glazed windows and wall tiles, but it may also happen on walls and ceilings, particularly in kitchens and bathrooms. If we insulate and warm the house thoroughly, you might think that condensation can be avoided, but unless we keep the moisture content of the air (the Relative Humidity - RH) below about 65-70% RH, condensation will form on the coldest surface. To control the Relative Humidity we need to balance heating with ventilation, or use a Dehumidifier. Without a Hygrometer to show you the actual Relative Humidity this is difficult to achieve.
Condensation is an extremely underestimated cause of damage to our homes. It can significantly contribute to spoiled paintwork, wallpaper and flaking plasterwork. All redecoration using paints should incorporate Anti-Mould Additive: avoid wallpapers if possible, (mould loves to grow in the lining) but if you must paper use an anti-mould wallpaper paste.
The condensed moisture can also react with the plaster ‘skim’ coat and cause ‘salting’ – you may need Salt Neutraliser to eliminate the salt before redecoration.
However, condensation mainly causes black mould on walls and ceilings and can damage our health. Sensitive people (e.g. asthmatics) can be adversely affected by the airborne spores. Apply Anti-Mould Cleaner to kill the spores before attempting any redecoration: decorating over the top of mould will not work – the mould simply re-grows through the paint or paper.
Black mould growth is the most common effect of condensation, but mould can appear in many other colours on carpets, clothing and wood.
This picture shows the effects of condensation in the corner of a room. Note the way that the black mould climbs and concentrates on the coldest part of the wall – an outside corner

If you have problems like this Property Repair Systems can help.
Anti-mould paints and anti-condensation coatings are available from Property Repair Systems Descriptions for each of these products are as follows:
A high quality coating recommended for use on areas not subject to abrasion or washing. Typically this means ceilings, underside of roofing sheets, ducting, steel building frames, pipework and inside cupboards. Lectros Anti-condensation Coating inhibits condensation by absorbing moisture and improving insulation; contains a biocide for the sole purpose of protecting the paint in the can applied film from mould growth.
- Keep furniture a little further away from the walls so the air has a free flow around the room.
- Do not fill cupboards to bursting point, again, allow the air to flow.
- Make sure the insulation in the loft is not blocking the ventilation provided by the gap between the facia boards and the house wall, or in a lot of cases these days, purpose made vents.
- Install cavity wall insulation, if permissible through building regulations in your home.
- Get the heating thermostatically controlled wherever possible.
- Ventilate tumble driers externally.
- Install extractor fans in the kitchen and bathroom. They are available with humidistat control.
- Install trickle vents in windows. The operation is not difficult. The vents come in two halves for inside and outside of the window. Several holes are drilled through the top of the widow head to allow air passage into and out of the room. Flaps are fitted so the vents can be closed and insect grills keep all the creepy crawlies on the outside !

Much more construction information is available in our bookstore. All the tools and fittings you need in the toolstore.