Condensation Control

Condensation is water which collects as droplets on a cold surface when humid air is in contact with it, and it is the most common form of unwanted dampness in buildings. On a daily basis we generate large amounts of moisture within our properties via cooking, baths, showers and drying clothes.

There is a lot you can do to reduce moisture levels and prevent condensation in your home and we have provided some guidance on this in our FAQs [link to FAQs]. We have also attached copies of our Condensation Guide for home owners, and our tenant version, which has costings removed, should you wish to provide your tenant with one. However, in some cases these measures may not be enough, and it is then that we would recommend that you seek our expertise.

There are a number of indicators that you may have a condensation problem in your property, including:

  • Water on the inside of windows
  • Water running down walls
  • Black spot mould
  • Fungal growths within wardrobes, on clothes or on furniture
  • A musty smell (caused by the fungus that accompanies the condensation)
  • Bedding feeling damp or cold
  • Feeling like you have a cold when you get out of bed (this is your nasal passage being affected by black spot mould spores)
  • Dampness or mould growths in corners, near windows, and in or behind wardrobes and cupboards

Black Spot Mould, indicating condensation, around a cold wall/ceiling junction and window frame

How to treat a condensation problem

If you suspect you have a condensation problem in your property, we would recommend that you have a survey done by one of our CSRT qualified surveyors. They will produce a report which will detail the cause of the problem and give recommendations for remedial measures. 

We carry out a full Condensation Assessment, which includes –

  • Wall temperature readings to determine how insulation is functioning and if any cold spots are present
  • Readings of relative humidity, temperature etc.
  • Types of mould present
  • Data Logging (over extended period if necessary)
  • Current ventilation assessment
  • General assessment of property, including lifestyle habits which may be affecting the problem
  • Full written report

The cost for this survey is around £300 +VAT (This may vary slightly depending on location and property type)

Our Condensation Assessment can be especially useful for occupiers who have struggled to get on top of the mould problem (many of our customers have spent hundreds, if not thousands having unnecessary repairs carried out, which have not fixed the problem), and tenants/landlords where there is uncertainty between the two parties over who is responsible, and how the problem should be resolved.

Once diagnosed, there are a number of measures that can be taken to rectify the problem.

Positive Input Ventilation Unit

This unit provides whole home ventilation and is suitable for most properties with a loft space. The unit ventilates the home from within and provides constant air circulation. They are typically installed in the loft space with a vent on the ceiling.

Extractor Fans

It is the Law (in accordance with Approved Document F) that properties have adequate ventilation. Extractor fans are necessary in wet rooms, i.e. bathroom and kitchen. This law applies to both new and existing buildings.

If there is a separate WC that has an opening window there doesn’t necessarily need to be an extract fan. A WC separate to the bathroom with no opening window should have its own fan fitted.

We recommend that extractor fans should always be continuous running fans. They have very low running costs and don’t rely on background ventilators as much as other fans.

Note – Background ventilators, such as trickle vents in windows, are not adequate ventilation on their own – they should be used to assist the flow of extractor fans.

There may be extractor fans already installed, but if they are poor quality or are not used, they will not help control the condensation problem. Existing fans may also require a service – blocked filters will significantly reduce the efficiency of a fan.

You should ensure you choose your installer carefully, Approved Document F sets out minimum flow rates depending on the location and property type – your installer must be aware of this.


Dehumidifiers can be an excellent way to tackle a condensation problem by taking moisture out of the air and into the unit.

Improving Insulation 

It’s not uncommon to have cold spots, especially on wall/ceiling junctions, where there are gaps in insulation/insulation has been disturbed, or around windows/doors. We can assess this and make the right recommendations to remove this defects.

Our team of experts can provide you with recommendations for the best ventilation units, extractor fans and dehumidifiers to suit your property so contact us today for a discussion.

Please feel free to download and share our condensation guides, from the links below –

Owner/Occupier –

[pdf-embedder url=”” title=”Condensation Guide Tenant Version”]

Tenant –

[pdf-embedder url=”” title=”Condensation Guide Owner Version”]

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