Condensation & mould | Connexus

Condensation & mould

Damp, condensation and mould in your home

Condensation can cause dampness and mould growth in your home. This looks unpleasant and can increase the risk of respiratory illness. It can also cause wooden window frames to rot. 

What is condensation?

Condensation starts as moisture in the air, usually produced by cooking, washing or drying clothes indoors on radiators. When it hits cool surfaces such as walls, mirrors and windows, it condenses and forms water droplets. The moist air rises when it is warm and often ends up on ceilings and in upstairs rooms and then it forms mould.

Why is it a problem?

Left untreated, condensation can result in mould growth on walls, ceilings, furniture, furnishings, and clothing in cupboards and drawers. It can also affect wall plaster and cause woodwork to rot. 

What are the different types of dampness? 

Condensation is caused by moisture in the air inside your home. Damp is generally caused by a fault in the structure of the building. 

There are two types of damp:  

  • Penetrating damp happens when water enters your home through an external problem, for example a crack in the wall or a loose roof tile.  

  • Rising damp is caused when the damp proof course breaks down. This then allows ground water to rise up walls and through solid floors.  

If you have a problem with damp in your home please contact us.

How to reduce condensation in your home

Control excess moisture  

  • Close kitchen and bathroom doors to prevent steam going into other cooler rooms.  
  • When cooking or washing, let the steam escape by opening a window or using an extractor fan if you have one. Leave the window open, or the extractor fan on for up to 20 minutes after you have finished cooking or washing. 
  • Open some windows in other rooms for a while each day and open any trickle vents in your window frames. This allows a change of air. If you do not have trickle vents utilise the second catch on your windows. 
  • Wipe down surfaces when moisture settles to prevent mould forming.  
  • Do not block air vents and allow air to circulate around furniture and cupboards.  
  • Do not use bottled gas or paraffin heaters – these produce a lot of moisture and they are also a health and safety risk. 

Produce less moisture  

  • Dry clothes outdoors whenever possible or use small ventilated rooms.  
  • Cover fish tanks and remember that house plants and pets produce moisture as well.  
  • Cover pans when cooking.  
  • If you have a tumble dryer or washing machine, ensure that it is vented in accordance with the manufacturer’s instructions. 

Keep your home warm  

Insulation and draft proofing will keep your home warmer and will also cut fuel bills. Maintain a low background heat when the weather is cold or wet. When the whole house is warmer condensation is less likely to form.  

Other advice  


  • Block permanent vents.  
  • Completely block chimneys.  
  • Draft proof rooms where there is condensation or mould growth.  
  • Draft proof a room where there is a gas cooker or a fuel-burning heater, for example a gas fire.  
  • Draft proof windows in the kitchen or bathroom.  
  • Put furniture against cold external walls.  
  • Turn off the extractor fan. 

What you need to do to control mould  

  • Treat any mould you may already have in your home, and then do what you can to reduce condensation. This will restrict new mould growth.  
  • Do not disturb by brushing or vacuum cleaning. This can increase the risk of respiratory problems.  
  • Wipe off mould growth immediately with water. Do not use washing up liquid.  
  • To kill and remove mould growth, wipe down affected areas with a fungicidal wash. This is available from hardware shops and supermarkets. Always follow the instructions carefully.  
  • Dry-clean clothes affected by mildew and shampoo carpets.  
  • After treatment, redecorate using fungicidal paint to help prevent mould recurring. This paint is not effective if it is overlaid with ordinary paint or wallpaper.