Condensation, damp and mould

Causes of damp and mould


Condensation is the most common cause of damp:

  • It forms when moisture in the air comes into contact with a cold surface like a window.
  • It left untreated it can lead to mould growing on walls, ceilings and even furniture. It can also affect woodwork and plaster.
  • Condensation mainly happens during the colder months, from September to April. It does not matter if the weather is wet or dry.
  • It is usually found in the corners of rooms, north facing walls and on or near windows.
  • It happens where there is little air circulation such as behind wardrobes and beds, especially when they are pushed up against external walls.

The amount of condensation in a home depends on:

  • how much water vapour is produced
  • how cold the property is
  • how much ventilation there is in the house.

There are some simple things you can do to help reduce condensation.

We can provide help for tenants with condensation, damp and mould.


Our everyday activities add extra moisture to the air inside our homes.

Here are some examples of how much moisture can be produced each day:

  • drying clothes indoors - six pints
  • cooking and boiling a kettle - six pints
  • two people at home for 16 hours - three pints
  • using a paraffin or bottled-gas heater - three pints
  • washing dishes - two pints

Find out about how to reduce moisture.

Other types of damp

Rising damp:

  • caused by water rising from the ground into the home
  • the water gets through a broken damp proof course or the brickwork if a property was built without one.
  • only affects cellars and ground floor rooms.
  • usually leaves a ‘tide mark’ low down on the wall
  • more noticeable in winter
  • left untreated, may cause wallpaper to lift and plaster to crumble

Penetrating damp:

  • only found on external walls or, in the case of a roof leak, on ceilings
  • appears because of a defect outside the home such as missing pointing to the brickwork, cracked rendering or broken/missing roof tiles
  • normally appears as a well-defined patch and feels damp to the touch
  • may cause wallpaper to lift and paster to crumble

Defective plumbing:

  • caused by leaks from water and/or waste pipes
  • affected area looks and feels damp

These types are damp are down to problems with the property, they do not usually result in black mould.

Tenants should report this to their landlord to get help with damp and mould.