Condensation and mould growth

Condensation and associated mould growth is a very common complaint. Mould growth is generally due to condensation that cannot readily escape.

It is rarely associated with true dampness.

To help you find the cause, read Shelter's guide to damp and mould in rented homes.

 Amount of moisture that can be produced in a day in a standard occupied property:

Amount of moisture that can be produced in a day in a standard occupied property
Activity Amount of water produced:
Two people active for one day 3 pints
Cooking and boiling a kettle 6 pints
Having a bath or shower 2 pints
Washing clothes 1 pint
Drying clothes 9 pints
Using a paraffin or bottled gas heater 3 pints
Total could be 24 pints in one day

How to avoid condensation

You can reduce moisture in the air by:

  • adequately heating your home (at least 18ºC)
  • ventilating your home properly – using windows and trickle vents
  • not blocking air vents or air bricks
  • drying clothes and towels outside (where possible)
  • covering pots and pans and closing kitchen doors when cooking
  • closing bathroom doors when bathing or showering
  • reducing the number of open water sources
  • wiping condensation off windows and surfaces

Condensation issues always increase during the winter when external temperatures are low and internal temperatures tend to be high.

When a surface has condensation on it, this can provide the ideal conditions for growth of mould spores.

How to deal with mould growth

Mould spores are present in the air all around us but it is only when the conditions are right – temperature, moisture level, lack of ventilation and a growing medium – that the mould spores will settle and grow on surfaces.


  • behind furniture and belongings
  • skirting boards and coving
  • ceiling edges and corners
  • carpets edges
  • window alcoves
  • all areas which may have poorer air movement, porous surfaces or colder surface temperatures and may attract excess moisture

You should:

  • clean mould off walls as soon as it appears with anti-fungal spray to stop it spreading
  • treat walls with anti-mould paint or use fungicidal resistant wallpaper paste
  • make sure all the instructions are followed to ensure the best results
  • wash clothes and belongings affected by mould growth with a suitable product
  • never remove mould spores with a brush or vacuum cleaner as this is likely to disperse the mould spores

Talk to your landlord or agent

Actions by both tenants and landlords may be needed to resolve condensation related issues, however making simple changes to avoid condensation in the first place will help greatly.

Your landlord may consider some upgrades to help for example:

  • the addition of trickle/passive vents in the windows
  • wall vents in affected areas and/or installation of air bricks
  • an upgrade to the heating system
  • installation of double glazing, cavity wall and loft insulation combined with suitable ventilation