A quick guide to condensation, damp & mould in rental properties

Condensation, damp and mould are common occurrences in most properties, especially in the
winter. As we start to transition from summer into autumn, you may find water condensing on
windows in the mornings, or the external walls may feel a little damp to touch.
You may be asking yourself why it keeps happening. Or perhaps you think it might be an issue with
your property. In this article, we’ll discuss the causes of condensation, damp and mould, as well as
different ways to treat and prevent it.

What is condensation and what are its causes?
Let’s start with a bit of science. Condensation occurs when water droplets created by warm air hit a
cold surface such as external walls and windows. Moisture in the air often comes from steam when
cooking and showering, or drying clothes indoors. We also exhale a small amount of water vapour
when we breathe.

What causes damp and mould?
If condensation isn’t addressed, it can lead to problems of mould and surface damp. Mould is a
fungus that grows on wet surfaces. As we just explained, you may find wet surfaces indoors when
there is excess moisture in the air that hits the walls or windows.

Damp can also be caused by damage or decay of the property, Water can penetrate the walls as a
result, causing damp that needs a damp proofing course. Rising damp can occur in basements or
ground floors but doesn’t generally result in mould growth.

As a tenant, you need to be aware of the things you could be doing that could contribute to
condensation and mould as well as what you are responsible to do to rectify and prevent it.

  • 1. Use appropriate cleaning products regularly
  • 2. Remove pooling moisture such as on windows and window sills regularly
  • 3. Use extractor fans when cooking and showering
  • 4. Increase airflow in the property by having windows open and leaving window vents open
  • 5. Limit drying clothes indoors (and when drying clothes indoors keep windows open)
  • 6. Run a reasonable amount of heating (ideal indoor temperatures are between 18°C and 20°C)
  • 7. Ensure furniture does not prevent airflow by being placed against walls or in front of

What are the responsibilities of a landlord/managing agent?
There are some preventative measures that landlords and/or managing agents can implement to
reduce mould growth and prevent damp.

  • 1. Decorate the property using a mould resistant paint
  • 2. Regularly inspect the property to check its condition and address any concerns before they
  • 3. Ensure the property is appropriately insulated
  • 4. Make sure the property has enough ventilation and extractor fans are kept in working order
  • 5. Show tenants how to use the heating system and thermostat controls correctly
  • 6. Repair any leaks or plumbing issues promptly

Condensation can sometimes be an inconvenience, but if left unaddressed can cause the
development of mould and damp which can cause even bigger problems.
If you’re unsure about an issue of damp or mould and who is responsible for resolving the issue,
always speak to your landlord or the managing agent. They’ll be able to give you the best advice to
help resolve the issue.

The most important things to remember are to keep good ventilation within the property, always
use extractor fans when showering or cooking, and clean areas of condensation regularly.