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'Its probably condensation' - The great condensation vs mould debate

When working as a Property Manager, if I received a pound for the amount of times a tenant had contacted me to report they had damp in their home and I needed to send a contractor immediately on behalf of their landlord to resolve it, and then when digging a bit further it had turned out to be bog-standard condensation, well, I would be retired on a yacht off the coast of Majorca right now. Unfortunately, this is not a reality and the amount of tenants that have sent me photos of mould below windows when the windows themselves are streaming with condensation is too many to count. The simple fact I have learned is that 9 times out of 10, it really is condensation and often tenants and even some landlords, don’t understand why this is being caused and will readily misdiagnose it as ‘severe damp’.

Tenants and landlords then cause themselves a lot of frustration throughout the tenancy by not dealing effectively with the condensation which results in unhappiness from both parties, the tenants’ belongings becoming covered in mould spores (and more often than not thrown away) and the landlords investment becoming damaged. From a Letting Agents perspective, I have dealt with countless complaints from tenants on this subject and I have often felt that a simple amount of information provided to tenants before their tenancy starts, could save everyone a lot of hassle.

So, what do you think about the below picture, is it damp or is it condensation?


What about the next one, what would your immediate reaction be, damp or condensation?


The answer is that the first picture AND the second picture are both condensation, both are caused by the way someone is living in a property rather than any structural issues and if you are a tenant renting out a property, it is important you understand the ways of combatting this. Landlords, it is also important you are able to spot this, so that you don’t spend money on unnecessary and expensive damp reports or repairs.

So what is condensation?

In an average household of four people each person will contribute approximately four pints of moisture per day through everyday living i.e. taking showers or baths, boiling kettles, cooking etc. This adds up to well over 100 pints of water vapour per week which is a huge volume of moisture that must go somewhere. Condensation is caused when you have warm moisture laden air hitting a cold surface. This is why you will often see windows streaming with moisture in the winter, the warm air from inside a home is hitting a window which is cold from the air outside.

The air we breathe can hold changeable amounts of water vapour, depending on its temperature. If warm moist air is cooled by a cold surface, such as a window or external wall, it is then no longer able to hold the same amount of water vapour. The air-borne moisture turns into droplets of water and collects on the cold surface.

When is it a problem in homes?

All homes get condensation occasionally - usually when lots of moisture and steam are being produced - for example, when a main meal is being cooked the moisture from the cooking gets into the air and will need somewhere to go. Similarly, this issue occurs in bathrooms from hot showers if windows are not opened or extractor fans turned on.

But, when is it really damp?

Occasionally, and I mean occasionally, the increased moisture in a property is not caused just by condensation but is due to other factors. Damp is generally only ever caused by leaking pipes, a leaking roof, a weakness in an external wall or rising damp.  Whereas condensation is surface dampness, leaks often result in patches of damp coming through the plaster and wallpaper near where the leak is. Rising damp can be identified by a damp 'tidemark' low down on the walls indoors.

Damp from a leak:                                                   


Rising damp:


Notice the difference in the first photos and the photos above?

If the issue is damp, then a qualified damp contractor will need to attend to carry out an intensive damp treatment course, generally costing a great deal. Tenants, if you spot one of the above two pictures occurring in your home then I advise you contact your landlord or managing agent to report it right away. P.s send pictures to speed things up.

What could condensation mean for a landlord or tenant in a rented property?

The maintaining of condensation is generally included as a clause within most Assured Shorthold Tenancy Agreements as a tenants’ responsibility. If a rented property does have severe condensation issues and the tenant does not maintain it themselves, a landlord can claim the costs back to repair any damage caused by the condensation from a tenant’s deposit. I have personally seen instances where entire bathrooms have had to be re-plastered and repainted as they were completely black with mould due to the tenants failing to report an extractor fan was broken, and failing to clean off the mould as it appeared every time they showered. Unfortunately, for this particular example, the landlord had to pay thousands of pounds to get her property back to the condition it was at the start of the tenancy in that room and others, and the tenants deposit although claimed in full, only made up a small proportion of these costs. Moreover, a tenant could also suffer damage to their own property if this mould is appearing (mouldy shoes in wardrobes are a good example) so it is important it is maintained and your tenants are educated continuously about the dangers of not keeping on top of it.


If you are a tenant and recognise the first two photos from this post from your home, please follow the steps in the acronym P-A-T-C-H below;

PRODUCE LESS water vapour - Many everyday activities add to the water vapour level in your home but their effect can be kept to a minimum.

  • Cooking - cover pans when you’re cooking and don't leave kettles and pans boiling longer than necessary. Ensure your extractor fan is turned on and a window is opened.
  • Drying clothes - Hang washing outside to dry whenever you can and if you have to use a tumble dryer make sure it's vented to the outside. Do not hang wet washing on radiators all around your home, doing so is very likely to cause condensation problems.
  • Bathing - Keep the bathroom door shut and the room well ventilated.

AIM TO VENTILATE your home - The best way to remove water vapour is by providing adequate ventilation. Nobody likes draughts but some ventilation is vital.

  • Keep a small window ajar, or a trickle ventilator open, in each occupied room to give background ventilation (but always make sure your home is still secure).
  • Open the windows to let the water vapour out, especially when you're doing the washing or cooking.
  • Windows near the ceiling are more effective at letting water vapour out than ones lower down.

TRY TO CONTAIN any water vapour/steam:

  • Your bathroom and kitchen are 'wet rooms' - keep these doors shut so that the wet air can't spread to the rest of your home. Especially when you're washing, cooking or taking a shower or bath, keep the door shut to stop the moist air spreading into the rest of your home. This is even more important if some of the other rooms are very cold. If rooms are not being used and are unheated it's a good idea to keep their doors shut.

CLEAN OFF SPORES when they appear:

  • When you notice mould spores or moisture appear on or around windows, ensure you clean it off with a cloth as soon as possible. You can also use a mould solution or a weak watered down with water bleach solution to clean away the mould which should help with stopping it returning

HEAT your home:

  • First of all, it needs to be ‘dry heat’ such as central heating or gas fires, not paraffin or portable gas heaters. The best approach to heating in order to reduce condensation, assuming you have taken the other four steps, is to heat your home at a low level for a long time. Keep the heating on but set it to provide just a minimum of background heating. This will warm the whole building up and keep it warm so there are no cold surfaces.

Tenants, if you follow these steps, then your condensation will be kept at bay and the condition of your home will likely stay the same throughout your tenancy. If you don’t, your landlord could hold you responsible for not following these steps and claim the cost of putting the property back to the condition it was at the start of the tenancy. Your own belongings could also be ruined and you will have no way of claiming this from your landlord as its technically your responsibility.

Landlords, it is helpful to advise your tenants of these steps before the tenancy begins, especially if you find the property is susceptible to condensation and keep reiterating these steps to your tenant throughout the tenancy if you notice a problem. If your property is managed by a Letting agent, they will often do this before the tenancy begins on your behalf and throughout following interim inspections if there are seen to be issues. Furthermore,  if you can prove you have provided this information to them, it will also help your case should you need to claim costs back from a deposit at the end of a tenancy. You may also wish to consider installing trickle vents, maintaining extractor fans and purchasing a dehumidifier for your tenants. At the end of the day, it is you that will be left to put the property back to an acceptable condition at the end of the tenancy if your tenants do not keep on top of it, so its best you put these steps in place before hand to limit this possibility.

Please get in contact if you have any queries or would like to share your own condensation/damp horror stories!

Angharad Trueman - Operations Manager


Posted on Friday, 17 February, 2017