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Condensation control units

The air naturally contains water vapour. The amount of moisture it can hold is determined by its temperature — warm air holds more water than cold air.

Condensation occurs when warm, moist air comes into contact with a cooler surface. The drop in temperature means it can no longer hold on to the same amount of moisture it was retaining, and the water is released onto the cooler surface.

Condensation can occur naturally as a result of changes in temperature or artificially by the actions of humans. In Britain it’s often a winter problem, usually caused when warm moist air generated in living areas comes into contact with colder parts of the building.

For condensation to form, the air must contain moisture. Water vapour can come from a number of sources within a home and it’s produced in relatively large quantities from normal everyday activities. A five-person household for example produces about 10 kg of airborne water each day:

• Breathing (asleep) 0.3 kg

• Breathing (awake) 0.85 kg

• Cooking 3.0 kg

• Personal washing 1.0 kg

• Washing and drying clothes 5.5 kg

• Heating — especially paraffin and flueless gas heaters. For every litre

of paraffin burnt, over one litre of moisture vaporises into the air. Even carbon fuel produces some water from combustion (1 kg of vapour equates to about 1 litre).

Moisture can also be drawn from the structure of the building into the internal air — from below the floor or through the walls and ceilings. Buildings often lack sufficient airbricks to allow adequate ventilation.

Condensation is often made worse by keeping the moist air in the property. In certain areas of a home, usually in bathrooms and kitchens, the warmer air contains a lot more moisture than other parts of the building.

New Homes


The materials used to build a house (mortar and plaster for example) contain a lot of moisture, which gradually dries out as the home is occupied and heated. But this can take some time, which is why newly built houses are especially prone to condensation. It usually takes 9–18 months for them to dry out completely and owners may need to use more heat during that time.

If you have moved into a new home you should take steps to prevent damage during the drying out process.


Older Properties 

Mature established properties have usually had many changes made throughout the years including new owners, extra building work and renovations carried out and the way that we live affects the ventilation and the creation of condensation. 


When originally built these properties would have had vents and air bricks that through time would normally have been covered up by carrying out various work and without realising the properties would have been adapted to be more energy efficient. With double glazing, loft insulation, felting roofs and sealants that stop any drafts from entering or exiting the property.


Modern living in an old property adds a large amount of humidity to the air via modern day heating, appliances, showers and drying clothes inside on radiators and maidens. 



One of the most noticeable effects of condensation, apart from water forming on cooler surfaces, is mould. This often looks like a collection black spots but it will completely cover a surface when conditions are right.

For mould to grow, there needs to be enough clean water available and relatively humid conditions for extended periods of time.


Mould can be removed by washing the surface with a bleach type solution. Special paints can also be applied to help prevent its growth. The only permanent solution to mould is to reduce the amount of condensation in

a property. 


Positive Input 

Ventilation Units

Remove and control the condensation in your property


Find out more...


What is condensation?

Condensation in new homes and older properties

Condensation mould and how to treat it

Roof Vents 


Tile & Slate vents

Remove and control the condensation in your loft space



Roof and loft space ventilation 

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