By far the most common cause of black mould appearing on walls is condensation, moisture laden air settling on cold surfaces. As hot air (steam) rises in a building, this usually appears worst in the higher parts of the house in bedrooms and bathrooms and on clothes in wardrobes which may develop a musty smell.

The true cause is complex but falls into two parts: either it’s the tenants’ fault, allowing excess steam to form and escape into the whole house through cooking, washing and drying wet clothes, or it’s the property itself having too many cold surfaces due to lack of effective insulation or insufficient heating. This complexity makes it very difficult to pin down the blame exactly on either the landlord or the tenant.

According to recent research carried out by energy switching comparison website Uswitch, as temperatures drop, around 62.5% of tenants have revealed they’ve experienced some degree of mould in their rental accommodation.

With this statistic in mind, Uswitch analysed the prevalence of mould across Britain and some of the potential causes.

Some key statistics revealed:

  • 64% of those who’ve experienced mould were tenants in privately rented, council, or student accommodation.
  • Two thirds of Brits believe mould is solely the landlord’s responsibility.
  • 2 out 5 tenants claimed they wouldn’t clean mould themselves.

For those that have had mould:

  • 40% stated that they dried their clothes indoors.
  • 21% had furniture directly against walls.
  • 22% leave the kitchen or bathroom door open when cooking or showering.
  • 12% admitted to having a cluttered home.
  • 11% confessed to keeping the shower curtain folded when wet.
  • and 6% leave spillages.

The UK’s mouldiest cities:

The Uswitch research indicates which UK cities have the highest prevalence of mould:

Uswitch Research

Sarah Broomfield, energy expert at, identifies the financial struggles of paying for heating as a major cause:

“It’s unacceptable that so many struggle to pay their heating bills. Those avoiding putting their heating on in fear of unaffordable costs, may inadvertently contribute to the growth of mould in their home”.

“With the findings that the majority of those who experience mould are tenants, it’s advisable that they contact their landlord to come to an agreement on how to tackle it. Tenants should also be aware that if they pay the heating bills themselves, they have the right to switch energy suppliers to find a cheaper deal.”

“Whether you’re a homeowner or tenant, if you find you’re struggling to pay your energy bills, there’s plenty of help out there — from government grants to supplier support,” says Uswitch.

It is a fact that inadequate heating leads to condensation and mould in a property. It is also a fact that many tenants fail to heat their accommodation adequately because of cost, but the cost of heating adequately, enough to prevent condensation and mould, can be increased considerably when the house is poorly insulated or the heating system is inefficient.

Older properties with solid uninsulated walls, which predominate in the rental sector, invariably cost far more to heat to an adequate standard than a modern building, and therefore they are prone to suffer most from condensation and black mould.

For a couple of years now it has been a requirement under the Minimum Energy Efficiency Standards for all new tenancies or tenancy renewals of properties rented in the private rented sector to be brought to a minimum energy performance rating of “E” on an Energy Performance Certificate.

Landlords are now being encouraged to exceed this minimum to at lease a least “C” which would considerably reduce the prevalence of complaints about mould.

Methodology: Uswitch surveyed 2000 adults across the UK asking 20 questions on the subject of mould.

Dampness & Condensation

How to Prevent Tennant Complaints about Damp, Mould & Condensation

Can't find what you are looking for?

Our helpful team are on hand to answer any queries and concerns you may have.

Get in Touch

This website uses cookies. We use cookies to provide social media features and to analyse our traffic.
You consent to our cookies if you continue to use our website. Read our cookie policy. I understand