A Landlord’s Guide to Mould in Rental Properties

By 11 min read • February 3, 2021

Fans of smelly blue cheese might not view mould as a problem, but in a home, it is both unsightly and a potential health hazard. Unfortunately, mould infestations are common, especially in damp areas of the home. In this article, we are going to look at mould under a magnifying glass – horrifying! 

We’ll investigate the causes of mould, who bears responsibility for the problem in a rental property, and how to deal with it. 

What is Mould?

Mould spores are found in most indoor environments, but it isn’t until the spores find a home and begin to grow that they cause a problem. Mould is a fungus. It thrives in damp conditions, which are common in the UK. When it breeds, it sends new spores floating through the air. This allows it to spread and start new mould colonies elsewhere. 

Mould needs specific conditions to grow in our homes: moisture, warmth, and food. Mould likes to feed on dust and wood, and it loves munching on carpets. Mould growing on surfaces may look nasty, but dead mould spores circulating in the air are also dangerous.

Mould in Rental Property UK

The presence of damp and mould in a rental property can easily strike fear into the heart of a landlord. When left untreated for long periods, a mould infestation is difficult to eradicate. It also looks nasty, which can be an issue if you need to re-let or sell the property.

There are a surprising number of rental properties in the UK that fail to meet the living standards set out in the Government’s Decent Homes Standard. This is because the properties have damp and mould issues that haven’t been adequately dealt with.

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Different Types of Mould

There are many different types of mould fungus, but the main varieties you are likely to see in a rental property include:

  • Mildew is the most common type of black mould and is often seen in areas of high humidity such as bathrooms. Mildew looks like black spots on walls and ceilings. When wiped with bleach, it fades away. 
  • Green mould is most unsightly. This may contain Penicillin, but it’s not good for your health. Green mould looks fluffy and can sometimes be found growing on damp carpets and soft furnishings. It can cause nasty respiratory problems. 
  • Blue mould is more common in moist bathrooms and is usually spotted on walls around showers and baths. It needs lots of moisture to grow, so a steamy shower cubicle is perfect. 
  • White mould has a furry appearance and is often spotted in damp cellars. It can look like the salt deposits (efflorescence) seen on damp masonry, but it won’t dissolve when water is sprayed on the surface. 

Toxic Black Mould

One variety of black mould worth mentioning is Stachybotrys chartarum, also known as toxic black mould. It needs a lot of moisture to grow. It is usually seen in chronic areas of damp, such as in cellars, on substrates where pipes have leaked, or bedrooms where the roof has sprung a hole and not been fixed. Toxic black mould looks almost identical to other types of black mould, but it is greenish-black and can sometimes appear slimy. The only sure-fire way to identify whether you have toxic black mould is to have it tested by an expert. 

Black Mould in Rental Property

There is a lot of alarming information out there that can worry a tenant who finds black mould in your rental property. The information suggests toxic black mould is highly dangerous and can even cause cancer, but in truth, this is a myth. Yes, it can trigger serious health problems in immunocompromised or vulnerable individuals, but it’s no more dangerous than any other type of mould. 

If a tenant contacts you with these concerns about your rental property, it is a good idea to let them know that there is lots of misinformation online regarding black mould. Make sure to let the tenants know that you will deal with the problem as quickly as possible to reassure them.

Why is Mould Dangerous?

Mould is an allergen. It releases mycotoxins, which can trigger allergic reactions in people with respiratory issues, such as asthmatics, or a chronic lung condition. It can also affect anyone with a weakened immune system, for example, babies, the elderly, and people undergoing chemotherapy.

Exposure to mould can trigger all kinds of symptoms, including:

  • Skin rashes
  • Respiratory problems such as a blocked or runny nose and sneezing
  • Red eyes
  • Asthma attacks
  • Headaches
  • Nausea
  • Insomnia
  • Fatigue
  • Sick building syndrome
  • Fever 

Some types of mould can cause severe reactions in people with pre-existing health problems.

Mould exposure is also known to trigger the production of bacteria and microbes, potentially leading to an inflammatory reaction in susceptible people. This can cause various health problems, such as hypersensitivity pneumonitis and bronchitis. 

The level of symptoms experienced by the affected person is usually linked to their underlying health and how much mould is present in the property. 

Mould exposure in healthy adults is not usually a big problem, but children tend to be more badly affected. A scientific study carried out in 2012 found that babies and young children were more likely to have developed asthma by the age of seven if they had been exposed to mould in their home.  

Where is Mould Usually Found?

Mould can appear on any surface under the right conditions, but it’s most common on cold surfaces like window sills and bathroom grout. It’s also commonly seen on walls and ceilings, usually in areas where airflow is restricted. This includes behind furniture or where the walls meet the ceiling. 

Mould is typically seen in bathrooms. These rooms are often poorly ventilated, especially in winter. Mould usually grows on silicone seals, tiles, and on the ceiling above baths and showers. Kitchens are another problem area, due to the high levels of condensation. Mould may also be an issue in bedrooms, but it can appear in any room where damp and condensation are a problem. 

Causes of Mould Infestations

The main cause of mould is condensation. This is where excessive moisture in the air lingers on surfaces, creating a breeding ground for fungal spores. Over time, these spores grow into specks of mould. Condensation is primarily the result of poor ventilation, usually from not opening windows to allow moist air to escape from kitchens and bathrooms and drying wet clothes indoors.

Mould can also be caused by structural problems, such as:

  • rising damp
  • penetrating damp
  • leaking pipes
  • loose roof tiles
  • blocked gutters
  • faulty extractor fans
  • rotten doors and windows. 

Another reason why mould might develop is that the heating system is inadequate or not used often enough. Cold air leads to condensation forming, which in turn provides optimum conditions for mould growth. It is better to have the heating on low all the time throughout the property rather than only heating one or two rooms. This prevents any significant temperature differences from causing condensation.

Poor insulation can lead to mould growth on ceilings and walls when moist air meets cold surfaces. 

Finally, mould is sometimes a problem in new-build properties that are still drying out. 

Who is Responsible for Mould Landlord or Tenant UK

Whether the landlord or tenant is responsible for mould or damp depends on the cause.

If there mould issue stems from a problem the landlord could’ve and should’ve fixed, they will be held responsible. If the tenant could have prevented the build-up of mould by ventilating the property more effectively, the responsibility is likely to be the tenants. 

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When is Mould the Landlord’s Fault?

When the mould is the result of a maintenance issue or structural problem in a rental property, the responsibility lies with the landlord. Landlords must also act if the mould is causing health and safety issues. The following case studies illustrate scenarios where a landlord could be blamed for mould problems in a rental property.

Rising Damp Causing Mould Case Study

John buys an old terrace property with rising damp. His budget won’t stretch to installing a new chemical damp proof course, so he gives the place a lick of paint and lets it out to a couple with two young children. Before long, paint is flaking off the damp walls and there is mould all over the lower portions of the downstairs rooms. This is an issue that John must sort out as it is caused by a structural issue.

Ingress of Water Causing Mould Case Study

Tanveer owns a rental property. His tenant tells him part of the gutter along the edge of the roof is broken and the bedroom wall is damp. Tanveer doesn’t fix the problem for a few months and when he finally carries out a property inspection, he notices black mould down the wall in the affected bedroom. Again, the landlord is responsible for making this damage right because he didn’t fix an earlier structural problem. 

Insufficient Heading Causing Mould Case Study

Agneta’s tenants inform her the heating in their rental property isn’t working properly – most of the radiators are not getting hot enough and the one in the bathroom isn’t working at all. Agneta doesn’t fix the problem in a timely manner and by the time the heating is fixed there is mould in the bathroom and bedroom. As Agneta didn’t fix the issue when she should have the resultant mould infestation is something she must rectify.

When is Mould the Tenants Responsibility?

Drying clothes on radiators and not ventilating bathrooms and kitchens can lead to mildew and mould growth. In the absence of structural problems such as rising damp, leaking pipes, or a broken extractor fan, the responsibility may lie with the tenant.

Mould doesn’t grow overnight, so keep a close eye on the property during inspections. It might be worth making your tenants aware of how mould and mildew can form if you notice they frequently dry clothes on radiators or if they don’t use the heating very often.  

Tenants’ Rights Damp and Mould UK

If a tenant notifies you about a damp or mould issue, you have a duty of care to your tenant to rectify the issue. This isn’t something you can leave to the tenant to fix, this is a legal responsibility that landlords have. Under the Housing Health and Safety Rating System (HHSRS), treating damp is compulsory.

More often than not, you will need to call a professional to find the cause of the problem and find a solution to avoid the mould from coming back.

Treating damp and mould in a timely manner will protect your tenants’ physical and mental health, protect the value of your property, and ensure that you are following the law.

Mould and Tenant Deposits for your Rental Property

If there are no obvious structural causes of a mould infestation and it is clear the damage has been caused by the tenant, a landlord may seek to deduct the cost of dealing with this from the tenant’s deposit.

In the event of a deposit dispute, the tenant can notify the deposit scheme where their deposit is being held that they do not agree with the landlord’s deduction. If this happens, the case will be sent to arbitration.

Mould Related Property Disputes

The problem with mould-related property disputes is that it is very difficult to prove who is at fault.

If the issue is caused by structural problems in the rental property, a tenant can hire a damp expert to produce a report stating an inadequate damp-proof course or poor insulation (or similar) is the problem. In the absence of such evidence, a property tribunal may rule in favour of the landlord. 

Mould and the Law Regarding Rental Properties

Mould is classed as a health hazard, along with damp and vermin infestations. It is always a good idea to consult an experienced property lawyer if you are involved in a mould-related dispute with your tenant.

Landlord and Tenant Act 1985 – section 11

Under section 11 of the Landlord and Tenant Act 1985, the landlord is required to resolve structural issues that could potentially lead to mould infestations.

Homes (Fitness for Human Habitation) Act 2018

The Homes (Fitness for Human Habitation) Act 2018 included an amendment to the Landlord and Tenant Act 1985. This allows tenants to apply to the court if they believe their rental home is “unfit for human habitation”, which it would be if excessive damp and condensation are causing significant mould problems.

Landlords are, therefore, obliged under law to ensure their properties are kept in an adequate state of repair throughout the duration of the tenancy. There is no liability if the tenant has breached the covenant by their own actions.

Under section 10 of The Homes (Fitness for Human Habitation) Act 2018, ventilation and freedom from damp are now listed as hazards that determine whether a rental property is unfit for human habitation

Government guidance for tenants clearly states that if damp and mould growth or the chemicals that treat mould growth are a problem, tenants can take action against their landlord. 

Tenants no longer have to deal with the local authority – they can take a landlord to court directly. Once a tenant notifies you of the problem, you have 14 days to reply in writing, stating how you plan on fixing the issue.

Note that tenants can’t be evicted within six months of them reporting an issue and you not fixing it. That would be classed as a retaliatory eviction. If you ignore a tenant’s complaint, the court can order you to pay compensation as well as ordering you to pay for the repairs. 

Dealing with a Mould Infestation in a Rental Property

As soon as a tenant notifies you there is mould in the rental property, organise an inspection so you can verify the extent of the problem. You have a two-week window to respond to a tenant’s complaint.

Identify the most likely cause of the mould. In an older property, look for signs of rising damp or penetrating damp. In a newer rental property, is there a hidden leak? If there is mould present in a bedroom, check the gutters to make sure there are no cracks or splits. Mould on a bedroom ceiling could indicate a roof problem – again, check this. 

If you find any structural problems, arrange for repairs to take place. Factor in the cost of replacing damaged plaster and redecorating the affected areas. If the issue is caused by poor ventilation, look at whether you can install a better extractor fan in the kitchen or supply the tenant with a dehumidifier to remove excess moisture.

Depending on how bad the mould problem is, you may be able to repair the damage yourself. Once the underlying problem has been fixed, remove flaking paint and loose debris from the walls and ceiling using a stiff brush. 

Make up a solution of 1:4 bleach and water. Scrub the area with a cloth until the mould has been removed. If there are still stains visible after the area is dry, repeat the process until all traces of the mould are gone. 

Open the window while you work, as bleach fumes are deeply unpleasant and a major irritant. Wear a face mask if necessary. 

Next, add white vinegar to a spray bottle and cover the affected area. The vinegar will penetrate into the surface and kill any remaining mould. This ensures it won’t grow back. 

Gaining Access to the Property to Make Repairs

Work with the tenant to organise a suitable day and time for the property inspection and subsequent repairs. Remember, you must give notice before you visit the rental property. Bear in mind that some tenants will be self-isolating or shielding, so be respectful of their situation and take steps to social distance if necessary. 

What Happens if the Tenant Fails to Notify the Landlord of a Problem?

A landlord can’t fix a problem he knows nothing about, so the onus is on the tenant to report mould when it arises. Always keep track of correspondence between you and the tenant, whether they use email, instant messaging, or voice calls. If there is a subsequent dispute, it will be helpful if you can produce detailed records that show how you and the tenant communicated during the period in question. 

Bonus Tip: Landlord Vision lets you track tenant-landlord correspondence in a tenant journal. 

Preventing Mould in a Rental Property

Adequate ventilation is the key to preventing a mould infestation in your property. Educate your tenants about the importance of regularly opening windows and airing rooms, especially rooms where there is high humidity such as bathrooms and kitchens. Modern homes with airtight UPVC windows have very little airflow unless a window is cracked open for at least 20 minutes a day.

Simple measures such as not drying laundry on radiators and putting lids on pans can make a difference. 

Make sure bathrooms and shower rooms have working extractor fans. These help to remove damp air, which is important during winter, as opening the window might not be an option on a freezing-cold day. 

Fix damp problems in older properties; properties with rising damp are very likely to have a mould problem. 

Don’t ignore maintenance issues, particularly exterior ones related to the roof and guttering. A cracked gutter might not be a major concern to you, but if it isn’t fixed, you might end up having to deal with a mould problem in the adjacent room.

When refitting a bathroom, consider upgrading to moisture resistant plasterboard for walls and ceilings. Use mould resistant paint on bathroom walls and ceilings. 

If there is a leak in your property, deal with it immediately. Replace water-damaged carpets and soft-furnishings so they don’t fester and become a breeding ground for fungi.

Consider investing in a dehumidifier to remove excess moisture from the air in the colder months. This is useful in family homes where washing machines, tumble driers, showers, etc. are running several times a day. 

Improve the level of insulation in the property. Well insulated properties are less likely to suffer from condensation problems. 

Be careful about furniture placement – try where possible to place wardrobes and other large items against internal walls. Leave a gap behind furniture so the air has a chance to circulate. 

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And Finally…

Don’t ignore mould problems in your rental property. They usually start off small but tend to grow at a frightening rate. Try not to get sucked into a blame game. Often, it’s not always clear-cut who is at fault. Many modern properties are so well insulated that it is very difficult to prevent condensation from building up. Always look at how you can make things better rather engaging in a protracted argument with the tenant. For example, fitting a better extractor fan in a bathroom might help to eliminate excess steam.

Be vigilant when you do property inspections; minor patches of mould in bathrooms and bedrooms are a sign of worse things to come.

Congratulations – you have reached the end of this report. We hope it hasn’t given you too many nightmares!

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