What you should know

Black, green or white mould? Musty smells? Condensation issues? Damp patches? Mould around windows, on furniture, mattresses, walls floors, ceilings and doors?

You won’t solve the problem with bleach and household cleaners. Mould will keep coming back unless you deal with the root cause. What’s more it can also affect your health and immune system, causing headaches, breathing difficulties, nausea, fatigue and even trigger respiratory problems and asthma.

Did you know:

  • Left untreated mould can grow into your walls and even affect building materials

  • Toxic black mould needs to be removed by a professional

  • Houses are becoming more airtight, without fresh air in your home, mould problems start


What is mould?

Mould is a microscopic organism that requires three things to grow: organic material (such as wood or paper), oxygen and moisture.

What causes mould?

Mould and damp are caused by excess moisture. Moisture in buildings can be caused by leaking pipes, rising damp in basements or ground floors, or rain seeping in because of damage to the roof or around window frames. In a newly built home damp can occur if the water used when the house was built is still drying out. The usual suspect for the cause of mould within your home is prolonged condensation. Continuous condensation problems are usually accompanied by black mould.

Is mould bad for my health?

Evidence suggests that mould can severely affect your health. It can cause headaches, breathing difficulties, nausea and fatigue. Mould is also a recognised allergen and irritant, and can trigger for more serious health problems such as respiratory problems and asthma. It can also be incredibly dangerous for those with a weakened immune system, babies, young children and the elderly.

How can I prevent moisture build up?

Without good air flow in your home, excess moisture may appear on your walls, windows and floors. To increase circulation, open doors between rooms, don’t dry clothes on radiators, move furniture away from walls, and open doors to closets that may be colder than the rooms they're in. Let fresh air in to reduce moisture and keep mould at bay. Ventilation removes moist air from the building through extractor fans and encourages air to move more freely through the building.

Is black mould harmful?

Black mould is a dangerous fungus also known as Stachybotrys Chartarum. If you do have black mould growing or starting to grow in your home, get rid of it immediately and then get rid of the source of moisture. If you find a colony of toxic mould do not disturb it. Touching or moving it can cause harmful spores to be released in the air – seek a mould specialist immediately. To clean mould on walls mix one part bleach to four parts water and with a damp cloth gently scrub and wipe the mould until it has gone, then dry with a soft cloth. Bleach and household products however are not permanent mould removal treatments, so mould will come back again and again.

What is condensation?

Ventilation prevents condensation problems by removing the moist air from the building through extractor fans. It also encourages air to move more freely through the building, preventing the air from becoming saturated and trapped in one area where it has time to release its moisture. Modern EnviroVent extractor fans include technology that allows them to respond to the humidity and increase the airflow to remove moist air more quickly. To address condensation development throughout the rest of a house, a whole house ventilation system may be required. These systems have a centralised pump which helps air flow into and out of all rooms in the building and prevents condensation settling into damp.

Everyday activities like cooking, showering and drying clothes create moisture in your home which can lead to condensation.

It can help if you:

- cover pans when cooking

- use extractor fans in kitchens and bathrooms

- close internal doors when cooking or showering

- leave a gap between furniture and external wall 

- Dry clothes outdoors or use a vented tumble dryer 

- Open bedroom windows for 5-10 minutes when you get up

Types of damp resulting in mould

Rising damp

When moisture beneath a building is soaked up into the bricks or concrete it is known as rising damp.

Rising damp is hard to deal with. Some buildings, for example older properties, are more vulnerable to rising damp. Sometimes it can be caused by a repair issue.

Penetrating damp

Penetrating damp is caused by water coming through external walls or the roof. It can also happen when there is an internal leak or plumbing problem.


Condensation is the most common form of damp in rented properties. It appears when excess moisture in the air comes into contact with a cold surface, such as a window or a cold wall.

It can lead to mould growth and tends to be worse in winter.

It can be caused by a tenant not ventilating or heating their home properly.

It can also be caused by poor insulation, or faulty heating and ventilation systems that are the responsibility of the landlord.

Heating your home

Try to keep your home properly heated. It usually helps to have a low background temperature of at least 15 degrees in all rooms.

Your Responsibilities

You are expected to properly ventilate and heat your home so that damp doesn't build up. This is sometimes called 'acting in a tenant like manner'. Your landlord shouldn’t make unreasonable demands. For example, asking you to dry your clothes outside when you don’t have access to an outdoor space.

Additional tool to help

Wave Mini

To help monitor air quality and risk of mould, the Wave Mini from Air Things (https://www.airthings.com/en-gb/wave-mini) is a super tool to make sure the air you breathe is clean, free from Radon and help you monitor the risk of damp conditions, which encourages the growth of Mould.


You can also use a dehumidifier with all of these solutions. But, while a dehumidifier is a great way of getting rid of condensation, you should always try to figure out what’s causing it. If there is an underlying issue you may need to run a dehumidifier all the time to see results. So, finding the cause of your condensation is key to proper treatment.

If you have already purchased a dehumidifier and now know that condensation isn’t the cause of your damp, don’t worry. A dehumidifier can be used to help with other types of damps too. A dehumidifier won’t solve your damp issues. Still, it can help you dry a room out once the damp has been found and treated.

If you do notice mould please report this as soon as possible by calling our office number, or emailing Contact@RJLpropertygroup.com

This way we can remedy the issue before it grows bigger and costs more to fix. If its seen as negligence, or left over a long period of time before reporting, then tenants maybe asked to contribute or pay the bill.

Please take note of this information, mould is a serious health issue and it can be easily prevented.

Rob Mason

Managing Director

RJL Property Group