Damp, Mould And Condensation In Rental Properties

Thursday, July 16, 2015
Damp, Mould And Condensation In Rental Properties

Damp, Mould And Condensation In Rental Properties

Guide To Damp, Mould And Condensation

Following on from our previous post explaining the responsibilities of tenants and landlords with regard to property maintenance in rented properties, our friends at Geo Property Lettings have supplied us with a brief guide to condensation, mould and damp in rental properties, so that landlords and tenants without tenants liability insurance can gain a better understanding of issues that commonly cost all or part of a tenants deposits.

There is a difference between damp and condensation – damp is usually caused by water ingress from various means including defective pipework or failed brickwork, whilst condensation is a naturally occurring phenomenon caused by lack of ventilation.

Condensation cannot be cured and is often misinterpreted by tenants as damp, however it is a bi-product of how all residential properties are used and under ventilated.

Condensation occurs where moist air comes into contact with air, or a surface, which is at a lower temperature.

Air contains water vapour in varying quantities, its capacity to do so is related to its temperature – as warm air holds more moisture than cold air.When moist air comes into contact with either colder air or a colder surface, the air is unable to retain the same amount of moisture and the water is released to form condensation in the air or onto the cooler surface.

Condensation is generally noticeable where it forms on non-absorbent surfaces (i.e. windows or tiles) but it can form on any surface and it may not be noticed until mould growth or rotting of material occurs.

In the UK, condensation in properties is mainly a winter problem particularly where warm moist air is generated in living areas and then penetrates to the colder parts of the property.

The moisture in the air can come from a number of sources within the property and water vapour is produced in relatively large quantities from normal day to day activities – a 5 person household contributes approximately 10 kg of water into the air every day (without taking into account any additional source such as central heating).

  • Breathing (asleep) 0.3 kg
  • Breathing (awake) 0.85 kg
  • Cooking 3 kg
  • Personal washing 1.0 kg
  • Washing and drying clothes 5.5 kg

For every litre of carbon fuel burnt over one litre of moisture vaporises into air produced by combustion and 1 kg of water equates to approximately 1 litre of water.

Moisture can also be drawn from the fabric structure of the building into the internal air; such as from below the floor or through walls and ceilings.

The effect of moisture generation is made worse by keeping the moist air in the property – it is possible to avoid condensation by adequately ventilating the property regularly.

Usually in certain areas of a property, such as bathrooms and kitchens, the warm air contains a lot more moisture than in other rooms, and if that air then spreads to cooler parts of the property, it will condense on any colder surface.

Properties constructed before the end of the last century were built with higher levels of natural ventilation integrated into the design as the level of insulation materials used in construction were low.

When energy conservation became popular, natural ventilation was greatly reduced by the introduction of loft insulation, cavity wall insulation, double glazing, draught excluders and fitted carpets which reduced the amount of natural airflow in properties and open fire places were also often replaced with central heating systems.

Properties have effectively become more airtight, keeping any moisture produced within the property, inside the property and ventilation is only effective if it is regularly consistent throughout the whole property.

Condensation is encouraged by poor air circulation where stagnant air pockets form behind furniture and in cupboards and the first evidence is often the appearance of mould growth.

Modern life styles mean that many rented properties remain unoccupied and unheated throughout the majority of the day, allowing the fabric of the building to cool down.

The moisture producing activities are then concentrated into a relatively short period (morning and evening) when the structure is relatively cold while the building is still warming up.

Tenants without tenants liability insurance should try to ensure that the amount of moisture they contribute into the air of a rental property is not excessive and they should examine their lifestyle within the rented property if they want to avoid having costly deductions made from their deposits.

  • After a bath or shower, ventilate the room to the outside, not to the rest of the house – just opening a window (and closing the door) will help.
  • Dry clothes out of doors or in a cool area of the property – this latter suggestion may sound strange, it will take longer but less moisture will be held in the air at any one time.
  • While drying clothes indoors, ventilate the room.
  • When people come in with wet coats, hang them outside the living area to dry, eg porch.
  • Try to increase the change of air in the premises – increase ventilation by opening windows.
  • Consider using a dehumidifier – domestic types are now available and can remove a surprising amount of water from the air.

If condensation does persist in rental properties, there are still some other changes to try, including:

    • Some wall surfaces can also be a problem. Where the wall is papered the situation may be made worse if there are many layers of paper, (this can just acts like blotting paper) so
    • Strip off all the layers and repaper the wall.
    • Things can also be improved by lining the wall with thin expanded polystyrene, usually available from wallpaper stockists, before hanging new wallpaper.
  • Where ceilings have a high gloss finish, consider papering or covering with fireproof cork or fibre tiles.
  • Solid floors are often cold because their large thermal mass takes a long time to warm up. Even vinyl floor tiles tend to be cold, however there are a number of warm flooring types available such as cork or cushion tiles. Thin wood flooring (laminate) can be fitted on top of most existing solid floors.

It is unlikely that rental properties will ever be damp, mould or condensation free, however by keeping rental properties correctly maintained, taking out specialist insurance policies to protect the tenant’s deposit funds and to cover the cost of damage caused to the property from accidental tenant damage and making tenants think about their lifestyle, both landlords and their tenants should be able to live with condensation without it ruining anyone’s life.


This was written by Mike Clarke. Posted on at 11:30 am. Filed under Insurance. Tagged , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , . Bookmark the permalink. Follow comments here with the RSS feed. Both comments and trackbacks are currently closed.