The causes of black mould and how landlords can reduce the risk

What can landlords do to keep home environments healthy and safe?

Modern living, COVID and challenging economic conditions are all inadvertently adding to increased damp and mould problems in homes. What can landlords do to keep home environments healthy and safe and protect properties for the longer term? 
 
Damp and mould in homes is a health hazard with potentially deadly consequences.  A two-year-old died in December 2020 from a respiratory condition caused by "extensive" mould. 
 
Landlords have a responsibility to make sure the homes they let are healthy and safe. If landlords undertake regular inspections of their properties, then a lot of these issues can be addressed early or avoided.  
 

What are the causes of black mould? 

There are many different causes of damp and mould, and there may be some simple solutions, but first, you need to investigate the source of the problem.  

External issues may cause internal condensation and damp patches. This could be a number of things, from a leaking pipe, waste drainage, rain seeping through roof tiles or rising damp due to a defective damp course.  
 
“We’ve seen a variety of external factors, which can cause issues internally, including faulty or incorrectly fitted rainwater goods, and even Damp Proof Courses (DPC) being pointed over, creating a by-pass allowing moisture to ascend,” says Alan Doherty, Partner, Carter Jonas. 
 
Internal issues can also build up from heating, insulation, and ventilation issues, but everyday activities may also contribute to condensation. Condensation can be common in residential properties that are poorly heated and poorly insulated, and the issues generally get worse in the colder winter months (October to April). 
 
Drying laundry indoors, having a shower or bath and cooking generate surprisingly large amounts of moisture inside a home. Humans and pets simply breathing also creates moisture in the air, and flexible working means we can be in our homes for longer periods.  
 
“We were surveying a semi-detached house with condensation problems. Only two adults lived there, but they had several dogs living inside the property, which contributed to the issues,” says Doherty. 

How can the issue be avoided or managed? 

However, none of this should be a problem with sufficient ventilation. It might be as simple as keeping the bathroom door closed when showering, using an extractor fan with the correct overrun setting or opening the window to let out any excess steam. 

This means the issue can be managed or reduced in some properties but is very difficult to eliminate completely. 
 
Drying clothes outside is always best, but that isn’t always an option, particularly for those living in flats without balconies or during bad weather. If drying laundry inside is the only option, moisture can be minimised by hanging washing in a bathroom or kitchen with an extractor fan or dehumidifier and ensuring the door is closed.  
 
“The position of furniture can also contribute to damp problems, so making sure large pieces of furniture such as bookcases and sofas are not located in front of radiators or external walls,” says William Eddy, Surveyor, Carter Jonas. 
  
“External walls tend to be colder, so leaving a ventilation gap between a piece of furniture and the wall allows air to circulate, which can help reduce issues.”  
 
No one likes to be told how to live, but sometimes, it might simply be a lack of awareness of how we live our lives, and some simple actions may reduce the impact of moisture. 
 
“We work with a number of housing associations who are good at offering tenants practical advice on reducing internal moisture and the risk of condensation,” says Doherty.  
 
“But there are also proactive steps landlords can take, such as undertaking regular checks to make sure that ventilation is up to scratch and extractor fans are in working order.” 
 
Sometimes, issues can be accidentally created. Natural ventilation measures such as air bricks may simply get blocked or covered because their importance is overlooked. 
 
There are external economic factors that may inadvertently play a part. High rents and mortgage rates may mean more people sharing a home than is typical to keep down costs. Overcrowding means the risk of more moisture naturally being created.
 
People may also have their heating on less during colder months to combat the steep rises in gas and electricity bills, but cooler homes are more prone to moisture. 
 
Closing trickle vents on windows can be seen as a way to minimise drafts and preserve as much internal heat as possible. And it’s similar for extractor fans in bathrooms and kitchens. 
 
“We’ve seen a few cases of extractor fans turned off at the isolation switch to save electricity,” says Doherty. 

Tenants have been known to turn off noisy extractor fans so they don’t disturb sleep, but good maintenance or a replacement fan can be an easy remedy.  
 
As part of regular landlord maintenance, uPVC windows should be checked to see if they still fit tightly, and trickle vents are in good working order. 

How to eliminate black mould completely  

Prevention is always best, but black mould can be removed with inexpensive cleaning solutions. In serious cases, once the source of the issue is rectified, walls may need to be hacked off, replastered and redecorated.   
 
Using an anti-fungicide paint when redecorating high-moisture areas in bathrooms and kitchens can help reduce the chance of reoccurrence. 
 
Retrofit options can involve a little more investment. For example, Positive Input Ventilation (PIV) in the loft can help circulate fresh air throughout the property. However, this is not the holy grail and needs to be carefully considered. Does it generate the required benefits for the cost outlay?  
 
Any insulation improvements must also be undertaken with adequate ventilation, otherwise it can increase the risk of condensation.  
 
The variety of housing stock means there isn’t a one-size-fits-all solution to preventing and treating damp. 

“How the property is used, and if the property has had a change of use, all have an impact,” says Doherty.

The problem needs to be treated holistically, looking at heating, insulation, and ventilation of the property altogether. 

“If you are suffering damp and mould issues, undertake an exterior survey first. Then, assess how the property is being used and follow the trail. It’s important not to jump to immediate conclusions and risk misdiagnosis,” he adds. 
 
For further information on this subject, please get in touch with one of our experts.